Spray foam vs. radiant in-floor heat
The title should be odd enough to grab some attention–here goes! I am building in Michigan with a walk-out basement. We are thinking hot water radiant, in-floor heat for the basement, forced air in rest of house. Our plan is to have the basement slab stained and leave exposed as the finished floor. Then the insulation contractor says that he can get similar comfort in basement by applying spray-foam insulation under basement slab and on the outside of the poured basement walls, claiming that the exposed interior concrete will have the same temp as ambient air and radiate that heat. Fair enough, but I am having trouble believing that it comes close to the comfort of in-floor heat. He swears it does, and says he’ll do an infrared (?) gun test to show temp of exposed concrete walls and slab floor in jobs he has done.
Anyone have experience with this, or care to weigh in with an opinion? Thanks!
Replies
He is out of his mind!
Go for the radiant with real 2" foam!
No bubble foil rubbish!
No foil foam rubbish!
Get a real heating contractor with a real heat loss and absolutely ensure the control stategy is done RIGHT.
Do you want heat or do you want to be comfortable?
Cheers and enjoy
Edited 11/26/2007 8:30 pm ET by s crough
He's selling foam, not much more than that. No way is a well insulated slab going to compare to the comfort of radiant. It just doesn't work that way.
Beer was created so carpenters wouldn't rule the world.
He is full of it.
When my radiaant is putting out and making my feet comforable it has water near a hundred degeees running through it. The surface I am placing my bare feet on can be 90° To get the same reading there with a hot air furnace, the air would be stifling and even hotter at shoulder level
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Welcome to Breaktime. Please use the search feature to locate and read some of the many excellent theads on radiant floor heat. All your questions will be answered and you'll be able to speak intelligently on the subject with a real heating contractor. But first ya gotta do your homework.
As the others have suggested, go with a full foam job and the RFH. The floor being heated to 90ish (the temp of your feet is normally about 91) with the insulation is far more comfortable than the heat without insulation or the insulation without heat. Insulation doesn't produce BTU's, and you'll need some to be comfortable. If you haven't added any, the room will draw it from the rest of the house.
Sounds to me like he is trying to sell spray foam. Go with the heated floor, and 2" Dow, you won't be sorry.
Sounds like 2" rigid foam (I'll do the DOW--I'm from Midland, Michigan, Dow's hometown) under slab with RFH is the way to go. I appreciate everyone's input.
Go to the 4inch foam the added cost will be returned in energy savings in a few years. That 50 deg earth under your house never warms up.
Westmich,
Actually, your insulation contractor is right. I disagree with all the other respondents who have commented on your original post. Here are some points to consider:
1. When it comes to investing in energy-efficiency upgrades, improvements to the building envelope are much more important than investements in heat-delivery equipment. That means ensuring a building envelope with very low levels of air infiltration and high levels of insulation.
2. While the use of spray foam instead of rigid foam board under a concrete slab is unusual, it will work fine. The thicker the foam, the better.
3. Assuming you get the building envelope right, and assuming you have installed thick foam insulation under the concrete slab, your concrete floor will, indeed, be much more comfortable (and closer to indoor room temperature) than the average poorly insulated slab.
4. In a well insulated house, a radiant floor heating system isn't on very often, and therefore the "warm toes" feeling doesn't happen very much. In other words, in-floor radiant is an excellent way to deliver heat to a poorly insulated house; in a well insulated house, it's probably a waste of money.
Martin, I understand your point. Do you think that spray in the entire house is worth the up-front expense of 2x or more compared to cellulose?Also, consider that we plan to leave the basement slab bare as finished floor. Assuming the entire house is insulated properly, will the rigid foam insulation under the slab be enough to keep the slab from feeling cold with socks on? I have lived in walkouts for years with no insulation under slab, and it's like walking on ice.
Westmich,
It is possible to build a very well insulated building envelope using cellulose insulation or spray foam; either will work. The important specifications are the air infiltration rate and the R-value. Be sure you are comparing apples to apples. To be sure you obtain the desired air infiltration rate, talk to your contractor to be sure he or she is familiar with blower door testing and has built houses that meet strict air infiltration targets in the past. You should require a blower door test to confirm the air leakage rate of your house.
The best cellulose-insulated walls are double 2x4 walls; these can be a total or 10 or 12 inches thick. If you are building with a single row of 2x4s, there won't be much room for cellulose.
If you are concerned that a concrete slab does not feel cold, it's important that you not have unrealistic expectations. Remember, if you choose to install an in-floor radiant heating loop in a well insulated house, there will be many hours -- probably the majority of winter hours -- when warm water is NOT circulating through the tubing in your floor. The best you can hope for in these circumstances is a floor slab at room temperature -- let's say 72 degrees (theoretically). Because indoor room temperature (72 degrees) is lower than human body temperature (98.6 degrees), the laws of physics dictate that bare feet on a room-temperature slab may feel cool, because heat will flow from human feet to the cooler material (the slab). Nevertheless, a well insulated room-temperature slab is going to feel far better than the typical poorly insulated 55 degree slab.
A well designed in-floor radiant system will be on continuously (24 hours a day) on only one day of the year -- the coldest day. For the rest of the winter, it will be cycling on and off. If your new house has a concrete floor that always has that delicious "warm toes" feeling, something is wrong -- a lot of heat is escaping your house somewhere, and your heating system is trying desperately to keep up with the heat loss.
Martin,
While I agree with much of what you say, there is one thing that I hope you will clarify for me. Is the compressive strength of spray foam predictable enough and consistent enough to risk using it under a slab? Does it finish smooth enough to be able to install heat tubing on top of it? I have no experience with spray foam myself and I don't know.
On the other hand, I do live in a well-insulated house with in-floor heating. In order to have that warm toes feeling, we run the system at a lower temperature than you might in a draftier house. Our floor temperature on a very cold day might be 85F. Because it runs a a fairly low temperature, we do get significant heat striping. I love it anyway.
Someone was telling me last year about a poorly built new house nearby with in-floor heat where they had to install baseboard convectors to supplement the in-floor because the floor temperatures were so high it was uncomfortable.
(They shoulda built ICF.)
Ron
Ron,
You raise an important point -- the question of whether spray foam insulation can be installed consistently enough for an engineer to predict its compressive characteristics. My first guess would be it can. (For example, roofing foam has a high compressive strength.) To my mind, conventional rigid foam sheets are the way to go when it comes to insulating below a slab. While I imagine that spray foam would work, I can't imagine any advantages -- unless you have a spray foam contractor who can install spray foam at a much lower price than rigid foam.
I'll agree with your first twopopints and as a dweller in a home that is both well insulated and using infloor radiant heat in the cellar I will disagree withthe latter two. the question here is the statement of the foam installer relative to "comfort" - not an objective standard of measurement of course.Your point that trhe floor heat wil only beoperating occasionally has little to do with it. The water warms the slkab and the slab very slowly radiates that heat from its ther,mal mass. That concrete will always be more comfortable with the radiant heat source than if it were wramed from the energy in the ambient air hovering over it. The air will always need to be warmer than the crete and the air aat shoulder head level will always be warmer than at the foot level. That might be fine if you are wearing your wool socks and slippers all the time, but most of us would define comfort a bit more comfortably.If you were simply speking to the overal cost of heating the dwelling, you might be right, but not with regrds to percieved comfort.
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Piffin,
On average, a slab with embedded hydronic tubing will, of course, be warmer than a slab without the hydronic heat, all other factors being equal. Whether or not that fact warrants the expense of installing the system is a judgment call.
I have written several articles about superinsulated houses built to drastically reduce the need for heat; in the northern US, this usually means homes with R-24 to R-40 walls and R-50 or R-60 ceilings, and triple-glazed windows. This can be expensive. (But in-floor radiant costs money, too.) The point is, when you make the leap to superinsulation, you reduce the need for space heat. Now you have a very well insulated house the needs only a tiny amount of extra heat, over and above the heat from lighting, appliances, pets, and human occupants.
If your house needs only a tiny amount of heat, there are many cheaper ways to provide it than in-floor radiant. If your slab has 6 inches of XPS under it, many northern homeowners will realize that slabs can be comfortable -- with or without in-floor radiant heat.
Hey, it's your money. You can spend it any way you want. If hot floors are important, put in the PEX. I'd rather spend the money on a better envelope myself.
As someone pointed out in a similar post elsewhere, the only way a bare concrete floor won't feel cool to bare feet, given its high conductivity relative to, say, carpeting, is if the concrete temperature is up in the 80s. If the house is well insulated, that 80+ degree concrete is going to boost the temperature in the air to the point where the room is too overheated for comfort. If the heat is on and the piggies are comfy, yet the room feels comfortable as well, then, as you pointed out, there is a big heat loss to the outside that the floor is trying to offset. The general advice in that other post was: insulate under the floor, forget the radiant heat, and wear slippers.
Dick,
Thanks for confirming my points!
>If the house is well insulated, that 80+ degree concrete is going to boost the temperature in the air to the point where the room is too overheated for comfort.You gotta get the btu's for the basement from somewhere, because insulation alone isn't enough to attain desired temps. The OP seems to lay out the two options as insulate and don't heat vs RFH with little insulation. If insulate and don't heat, from where will the btu's come? Through the ceiling from the living quarters above?As I'm typing this, I'm having second thoughts because of one word--basement. This isn't the main floor and these aren't bedrooms. It's the basement, and I'd be less concerned about comfort in the basement than in the other parts of the house.I had a super-insulated house with high mass. 3-4" of spray polyurethane (closed cell) foam _continuous_ to the exterior of solid concrete walls and roof. We also had RFH on all three levels. Never ran the zones in the basement, yet it still would not get lower than 67/69 on the worst days of winter. It got it's heat from the main floor slab above. On that main floor, we benefitted from the comfortable floor and were barefoot all year. The basement had colder floors, but we didn't live in the basement, so we didn't care.Since this is a basement, then, insulate it and provide as little heat as necessary for its purpose. If it was a main floor, insulate it, provide rfh for heat and comfort if it's in the budget, and use an HVAC contractor who knows how to balance that with the insulation.
Edited 11/27/2007 11:00 am ET by CloudHidden
OP here,I can easily have runs to the basement for the FA heat--the RFH was for comfort as we use the walkout basement extensively (guest bedroom and bath are going in there). I don't have the budget for RFH in basement (8500, in addition to FA heat) to spray the entire house (around 15k for a 2500 SF house, plus the basement (1400 sf, 1000 of which will be lived in). I am trying to conclude the best way to have a comfortable basement and still have exposed and stained concrete floors down there. It appears I have a choice to make: best possible whole-house insulation package, which appears from this board to be sprayed foam top to bottom, vs. RFH with "standard" insulation of rigid foam on poured walls and under slab with cellulose blown in the rest of the house.
What struck me as odd about your proposal is that some of the house would be radiant in floor and some of it would be forced air at the same time you are focusing on comfort. The reason it seems odd is that you are needing to employ two separate heat plants to supply this and that I have never considered forced hot air heat a 'comfortable' choice.
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I agree that forced air is not the most comfortable, but for the cost I don't really mind forced air above grade other than the dryness in winter. I will definitely have A/C and therefore the ductwork, so the addition of a high-efficiency natural gas furnace makes sense, or doesn't it? I have a feeling this group is going to ask me if I have not been paying attention!
My neighbor has radiant heat and he complains that above grade it takes a long time to heat up and cool down, but he loves it in the basement.
The combo HVAC duct sharing does make sense if you tolerate that sort of distribution system.I grew p with it, but it bothers me now.As for your neighbor - he is not using it right if he is turning it up and down and expecting fast responce. Radiant uses the thermal mass to achieve steady state. There can be a four hour to a three day lag curve, depending...Set the thermostat to the temp you are confortabale at and leave it alone.
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forced hot air doesn't have to be uncomfortable... properly sized , with an in-line humidifier
it would be a natural choice
our next addition is going to have RFH & A/CMike Smith Rhode Island : Design / Build / Repair / Restore
you should check out this thread ... it has super insulation, RFH, & A/C...... on a budget
http://forums.taunton.com/tp-breaktime/messages?msg=92880.1Mike Smith Rhode Island : Design / Build / Repair / Restore
or this one... it has superinsulation, A/C, a daylight basement, and hot water baseboard
http://forums.taunton.com/tp-breaktime/messages?msg=67972.1Mike Smith Rhode Island : Design / Build / Repair / Restore
westmich,
There is an alternative to duct work and A/C , actually several alternatives.. many of them are in expensive and effective.
There is an alternative to duct work and A/C , actually several alternatives.. many of them are in expensive and effective.
Frenchy, I am all ears (eyes, really)--what are the good alternatives to a/c and ducts? You have my attention...
westmich,
Let's look at my solution. I wanted in floor radiant heat and A/C (I also wanted a back up of forced hot air but I digress),
So what I did is go out and measure several room A/C units.. I settled on a couple of standardized sizes and cut holes in my SIP's and stuck the A/C units in the holes.. For less than $1000 I had A/C! (I bought the highest efficency window units available in those sizes).. 3 small units keep my home really comfortable. {remember with SIP's I don't have the heat gain or loss of stick building} My electrical costs are really trival.
Since I trimmed the cut outs on the inside I can put picturesto cover the cut outs and on the outside it will match the wall. Fall comes I pull the A/C units out put the plugs back in and store the units in the attic untill summer.
You could also use mini ducts (about 2 1/2 inch) which is far less expensive than typical duct work. Another option is you could use seperate head units, they require only small (1 inch typical) holes to feed. Not major duct work..
>You could also use mini ducts (about 2 1/2 inch) which is far less expensive than typical duct work.The mini-duct systems (Unico, for example) I've used come at a premium to traditional ducted HVAC.
Cloud Hidden,
When I looked into it it was cheaper.. Not by much, but I still considered doing it because unlike regular A/C which comes out low and tends to remain low (Cold air falls, warm air rises) it comes out high and settles down.
At one time I was going with two sets of ducts,, low for forced hot air and up high for A/C
Instead I used my cheap window A/C units in the wall and set them high.. use in floor radiant heat down low and have only 6 ducts for back up forced hot air..
First it was "far less expensive," and now "it was cheaper.. Not by much."I did use it, and paid for it. I like the high velocity, small duct systems, but cheaper they aren't.
Cloud Hidden,
It was cheaper/less expensive than running duct work according to the guys I spoke with.. They use a milwaukee self feeding drill bit and bore holes wherever required. Then feed that flexible tubing thru and the duct work portion is done. Which is a lot easier than cutting holes and fabricating rigid ductwork. They're in and out in a half a day compared to ductwork guys spending a couple of days..
The A/C unit itself was more expensive than a normal A/C add on unit but the combined still was cheaper, again not by a lot.
I can not understand if you want a truly well insulated easy to heat home why not go with ICF's? I plan on building here in south central AK (10Kdegree days) with RFH, concrete floors on two levels and possibly a full basement. I will be putting in RFH in the basement in the slab as well. I also plan to insulate under the slab.
I would be concerned in my climate if I did not have heat in the basement slab about the potential depending of course on the soils and drainage etc that unless the basement is well below the frost level of frost heave conditions. Heated slab would make that an unlikely occurrence. Also would not the heated basement make it easier to heat the floor above and reduce the load on the boiler?
Jim
You are re-focusing on the question of comfort level re it being a basement.It still goes to needed comfort level. For myself, the basement is where I spend my time between the office and the other office, and when I am not physically active on the job, my personal needs for thermal comfort are high. My wife OTOH likes it about 62°, so it works well to heat the basement walkout with the radiant in floor heat for my comfort and then the residual heat rising to the main level means that zone is not very active and we are both "comfortable"!
;)I know I have never had a customer who did not enjoy the comfort they had from radiant floor heat.
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> never had a customer who did not enjoy the comfort they had from radiant floor heatAnd you know I'm a big fan, too. This poster says he can't do both--rfh and serious insulation. So what's a person to do?
"So what's a person to do?"A discussion like this is a good place to start! lots of objective and subjetive pros and cons brought out to consider and in the end, the customer is always right.
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That's the rub, my budget does not allow for both supertight AND radiant. So what IS a fella to do? Maybe the proper thing to do is design the home around the heating, cooling and energy efficiency costs and take the rest of the project from there.
I am leaning toward super insulation, betting that heating costs are going up steadily over the 10-12 years I plan to be in this house. I also will have a wood-burning fireplace on main level, dead center of the house. Main floor is all common space (1400 sf), bedrooms upstairs (1100 SF) and basement has guest bedroom and bath.
We will be using the basement recreationally a lot over the years for shooting pool, watching movies, etc., and with no in-floor heat I would be betting that 4" of insulation under the slab, super-insulating the rest and making the house really tight wil keep the basement cozy enough.
Given a budget based decision of super tight or radiant I'd go for super tight every time. Radiant is a great way to heat a space but you still need the same number of BTUs from radiant of forced air to heat the house. super tight will reduce the number of BTUs (i.e. dollars) needed to heat the house. Every $20 you save per month on your power bill is equal to $3,000 off a 30 year mortgage. Radiant heat is wonderful, I heat that way myself, but saving energy comes from tight and well insulated construction systems and spray foam is your best bet for that. ------------------
"You cannot work hard enough to make up for a sloppy estimate."
Shelternerd, thanks for the advice. I tend to agree. Now I have to figure how to get the right HVAC person to calculate the proper needs for expected performance without charging me 22k for a smallish FA system.
Not all HVAC people I have talked to get the supertight insuloation idea. They want to approach it like a standard code-based insulation house and don't speak the language I expect from someone going after high efficiency. I am a little dissappointed in my inability to find a HVAC contractor who seemsto get what I'm doing.
Try going to the DOE Energy Star website and finding a local Energy Star HERS rater. Ask them what they would charge to run a Manual J calc and size a system to meet your plans and specs and to follow up and test the installation (blower door and duct blaster) and give it an energy star certificate when done. I pay $900 total for this service per house here in NC and it lets me give my HVAC guy an independently calculated Manual J to back up the proper sizing of the system. These guys also know who does good work because they test the systems all day every day.------------------
"You cannot work hard enough to make up for a sloppy estimate."
I'll take that advice, thanks
westmich,
My 55000 sq.ft. "superinsulated" home is very comfrotable with 90,000 btu furnace, but it's vastly oversized and inefficent..
When finished I'll have that big furnace only for those 30 below days with wind chill approaching triple didgets. If you have anything like a well insulated house go much, much, smaller than advised.. If you aren't here in the fridgid north (Minnesota) I'd be tempted to say 1/3 of that size (except I'd still go with radiant heat. remember the coldest part of a forced air room is the floor.. that's where your body feels cold first and most)...
warm floor and the rest of the house can be cooler and still more comfortable..
Thanks, Frenchy. Grand Rapids, Michigan isn't as cold as wen I lived in La Crosse, WI, but it ain't exactly Florida either.
Tell me if this is a crazy idea: to save some money but get the best of all worlds, what if I do superinsulation with spray foam, high-efficiancy wood fireplace on main level, forced air nat gas, and electric in-floor in master bath and under a 10x10 area in basement slab where we are likely to lay on the floor for watching movies, etc.?
So I have 3 heat sources: gas, wood and electric for spot comfort, and I have an energy efficient envelope for years of comfort and savings.
I think a small spot of regular hydronic radiant would be cheaper than an electric mat depending on the water heater.------------------
"You cannot work hard enough to make up for a sloppy estimate."
couple things...
i still don't have a good picture of your project in my head
but: the insulation package seems very expensive... i think i could do better but i would give up some btu's
the HVAC is screwing your budget....
and you're including a combustion source inside your house
since you are at the mercy of your contractors , you don't have the flexibility that i have so that is a major constraint
i'm going to go back thru the thread and see what i've missed or confirm what i think i knowMike Smith Rhode Island : Design / Build / Repair / Restore
i think you are building a two story house with a walk-out basement... the 2d floor is under the roof ?
so a 1 3/4 story house with a walk-out basement
first i'm a little of a contrarian..
i don't want or care that i have the concrete as part of my heated mass
so i would insulate the basement from the inside.... the same way i did in Adverse Conditions, with the same materials... and the includes 2"xps under the slab treated with borates... that method is an evolution of 30 years of insulated basements .. basically the same way Andy Engel did in the FHB article
2d.. i'd go Mooney wall on the exterior....
i'd use a good quality insulated window with hi-performance glazing .. unless you can find a triple glazed window that will stand the test of time
i'd have an R-60 attic...
and i'd blower-door test everything and air seal the areas that need attention
so .. in my package i'd have the following assumptions:
half your foundation is buried ... the underlying soil is at 45
the exterior design temp is zero
i don't know what your Degree Days are ... but it wouldn't surprise me if they are 8000
the interior design temp is 70
i'd get rid of the high efficiency fireplace... if you want to heat with wood... get one of those Outdoor woodburners and pipe the hot water into your house
for the A/C... i'd do just what Frenchy did
<<<So what I did is go out and measure several room A/C units.. I settled on a couple of standardized sizes and cut holes in my SIP's and stuck the A/C units in the holes.. For less than $1000 I had A/C! (I bought the highest efficency window units available in those sizes).. 3 small units keep my home really comfortable. {remember with SIP's I don't have the heat gain or loss of stick building} My electrical costs are really trival. >>>
ducted A/C is great... but expensive...
split systems cost a lot of money
thru-wall units run about $600 apiece
window units run from $80 to $160 each.... in a super insulated house you could probably cool the whole thing with 4 startegically placed window units installed the way Frenchy did ( like i did in #RFH Ranch #
i'f have RFH in the basement and a staple- up on the first floor & the 2d floor
that would be my heat..
i'd have a humidifier for the basement and one for the 1st/2d floor..
i might tie the humidifiers into a whole house heat exchange / vent system to introduce air changes
or..... i'd ignore everyone here and go with your local contractors.....
it's your house, your money...
so , there you have it... another opinion
Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike, I think that is the first full answer/opinion to be supplied on this thread--insulation, cooling and heating details in one post. What it gives me is a good option that appears to be very affordable. My housing by-laws do not allow windor a/c units, but the rest sounds good.
The wood fireplace is for ambience and emergency heating. Do you suggest nixing it because it is unnecessary or because it's somehow detrimental?
if it's for ambiance... then the gas log / glass door fireplace works great
for heating .... fireplaces .. even "efficient " ones are a major loss
and they become indoor air contaminators... also very difficult to balance the relative humidity with a fireplace.. or even a woodstoveMike Smith Rhode Island : Design / Build / Repair / Restore
The house is a traditional rectangular 2-story farmhouse, with a walkout basement, so 3 floors total. footprint=1400 SF, upper floor is 1100 sf. Bedrooms are upstairs and one bed/bath in basement. In Susan Susarka's "Not So Big House" book it is the one called "Field of Dreams". Detached Garage.
What I am wrestling with is the insulation/HVAC combination. I want to be very energy efficient and also have wood backup in case of emergency. Love warm floors, but if I can achieve comparable or satisfactory indoor comfort with great insulation on all floors I can forgo the cost of in-floor heat.
Does that help?
my customer in Adverse Conditions .. has a woodstove backup in his basement..
if he wants to , or needs to, he can pull the boiler flue out of the thimble and insert his woodstove pipe.. and he's good to go
the heat loss from his boiler .. often just heating DHW keeps his basement at 70Mike Smith Rhode Island : Design / Build / Repair / Restore
Could you explain the combo open and closed spray in foam bid? What, where, and why?<G>I recently had 3052sq', 2x4 walled, 2 story, foamed with open cell Demilec. Including garage ceiling and crawl space band, it was under 10k. Conditioning the crawl with 1 1/2" of foam plus plus 10 mil vapor barrior, would have added 3k more... so, your price of 15k doesn't seem out of line for the job scope.Split zone dual-fuel forced air system, around 14k... I know it's not apples to apples, but your HVAC bid seems like the killer.Throwing something else into the mix, would a geothermal system work for you? Got room for a ground loop? Winterlude, Winterlude, my little daisy,
Winterlude by the telephone wire,
Winterlude, it's makin' me lazy,
Come on, sit by the logs in the fire.
The moonlight reflects from the window
Where the snowflakes, they cover the sand.
Come out tonight, ev'rything will be tight,
Winterlude, this dude thinks you're grand.
Snort,
by duel-fuel, do you mean good for either nat gas or propane?
"Could you explain the combo open and closed spray in foam bid? What, where, and why?"
Here's the insulation package as bid. Closed cell (rigid foam) used for waterproofing, I think.
soft foam 3" in all exterior walls, gable ends and under electric in-floor heating in master bath area
soft foam 4" in rim joist area
soft foam 6" sprayed against non-vented roof deck and mud room and piano corner (noon of dining room) and down on drywall lid of second story and vented attic
install caulk and seal pakage
total: $11,560
OPTIONS
rigid foam (closed cell) 1" sprayed under slab and on exterior of foundation walls, $3,780 (closed cell here for waterproofing)
R-11 fiberglass soundbatt between bathrooms, bedrooms, laundry and common living space (1,314 SF), $730
Detached garage insulation r-13 kraft batts in walls and loose fill r-30 in attic area, $1,480
Check out R-Control SIPS. Last time I checked the plant was near the airport in GR.If the design of the house in to to cut up Sips are easy. With a conventional roof system I'd lean do energy heal trusses and cellulose or open cell(soft) foam in the roof system. My Sip house (1550 sqft) has staple up designed at 15btu/sqft and it rarely runs the mod-con boiler above the low setting (20k btu). About exactly what the design calls for 15x1150=23250 x.92=21390.I'm also a certified demilac installer but I don't belive the 3" in the walls and 6" in the attic argument. R values just are not high enough especially when you include the studs in the walls in our cold climate. Garett
I'm also a certified demilac installer but I don't belive the 3" in the walls and 6" in the attic argument. R values just are not high enough especially when you include the studs in the walls in our cold climate.
If you don't use SIP or ICF, how do you get the best insulated 2x4 walls if not with spray foam? I can't imagine blown cellulose is better, or is it?
I am driving my builder nuts by not signing a build contract until we figure out insulation and HVAC. Seems now I might add the idea of SIP and ICF to the equation, since it appears to be a good way to go.
I understand that R-values are not really the test of a home's efficiency performance and does not address comfort from equal temp throughout a home. But the SIP websites do list r-value of the panels, perhaps because people expect them to list that standard measure of insulation (weather it means anythign or not).
So when they list 14.5 R-value for the SIP walls, I am not to be scared by that low number right??
Westmich
I have R control SIP's six inches thick for the walls and 10 inches thick for the ceiling/roof.
Remember with traditional stick built homes there is a stud every 16 inches, sometimes doubled up or even more.. that's where the wall has no insulation and the only R value is the R value of solid wood (pretty darn low about 1 per inch so a 2x4 is actaully an R value of 3.5) when rating a stick built house if the R value is claimed to be 13 it's at best 80% of that 13 because of the studs.. SIP's have no studs.. so their R value is correct.
* windows and such lower the rating even further.
However the issue gets more complex.. Given all that I know and all I've experianced I would build with ICF's in the walls up to the ceiling.. .
Grott,
I too Used R control SIP's. My plant was also nearby and it was nice to simply go there to pick up panels rather than have them stacked around untill I could use them..
I will save having built with both SIP's and ICF's if I were to build again I would use use ICF's for the walls and SIP's for the roof.
dual fuel is electric/propane. Your insulation package sounds like what would be installed here, in NC. I'd think it would be beefed up for your area, but perhaps with the foam stopping air movement, it is enough.How is the closed cell foam that is above grade on the foundation treated? Winterlude, Winterlude, my little daisy,
Winterlude by the telephone wire,
Winterlude, it's makin' me lazy,
Come on, sit by the logs in the fire.
The moonlight reflects from the window
Where the snowflakes, they cover the sand.
Come out tonight, ev'rything will be tight,
Winterlude, this dude thinks you're grand.
As far as I could tell it is simply sprayed onto the vertical concrete and backfilled like that, with the foam exposed. The benefit is supposed to be that there are no seams and the corners are also sealed without gaps. I have yet to compare the cost to (2) layers of 2" foam with staped and taggered joints, which would likely yield similar results.
"dual fuel is electric/propane."Usually the term electric (heat) is used for resistive electrical heat.And typically when I hear dual fuel they are talking about heat pumps with gas burner aux heat..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
That's it, sorry for being clear as mud. Winterlude, Winterlude, my little daisy,
Winterlude by the telephone wire,
Winterlude, it's makin' me lazy,
Come on, sit by the logs in the fire.
The moonlight reflects from the window
Where the snowflakes, they cover the sand.
Come out tonight, ev'rything will be tight,
Winterlude, this dude thinks you're grand.
Very unlikely to be true, unless there is an existing hot water heating system to tie into.Once you've added the necessary "initial components", you might as well have done an electric mat if you're just going to do a small area.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
westmich,
Call your local cement companies have them send someone out to give you a quote on an ICF house, using your plans.. Show them your quotes so they have a price to shoot for..
Wood fireplaces usually burn heated air and send the exhaust up the chiminey.. if you've got someone who will sell you a wood buring fireplace that draws outside air in you can achieve some decent real world efficencies otherwise you're using invalid numbers..
Now wood, what's your source for it? I was able to buy a cord or so or hardwood for $25.00, I'd go to sawmills and buy their slab wood (the first cut) and at that price it was competitive with natural gas.. However, that ignored all the rest of the work. cutting it to length hauling it dealing with the mess , ashes etc.. when I added the cost of the (in my case ) fireplace and the rest of it I went another direction..
I still will have a fireplace but it's on the back burner untill I'm closer to finished..
Direct use of electricity for in floor isn't terribly cost effective.. that's why I went to all the hassle of electric water heaters and in floor radiant.
I don't know what your electric rates would be there in Michigan,, do you get a cheap rate from Niagra Falls?
I do like the three sources idea. Just not sure you've picked the 3 best sources.
Frenchy, I have read (I think from you and a couple others) that ICF and SIP construction could be the same cost of stick built within a few percent if you have the right contractors with experience and who are not charging the HO to learn on the job, so to speak.
Is that the same cost as just the framing materials, or the same cost as framing materials plus insulating he stick built frame?
Then how do they run lines for electric and heat runs, etc., if there are no interior studs?
westmich,
The same as a stick built house with insulation.. (cost wise) +-2% for ICF's I don't know for SIP's I couldn't find an aggressive SIP builder. Material costs for my SIP's were actually lower than material costs for a similar stick built house with insulation, labor costs should be lower since they go up faster.. It's not untypical to have a 2500 sq.ft. house done with SIP's framed in 1 day.. Like all things though if they don't know the steps to take it may be a week or more.. Once I found the big short cut my time was dramatically cut..
Interior walls are still stick built with either system.. that's where you run plumbing.. in cold weather you should never run water in exterior walls, if you have a sink against an outside wall for example the plumbing comes up thru the floor same as a stick built house should do..
Wiring is easy with SIP's. long spade bits with extensions makes putting romex so simple it's actually fun, or you can order most panels with wire chases already in them for no up charge, that way they set the chase back far enough so that sheet rock screws can't puncture it. The third way which is often done but not approved is they simply cut a groove wherever they want a wire and then simply foam it back into place once the wire is in place.
By the way your sheetrockers will love SIPs you can't miss! Anyplace you put a screw you'll hit!
Hanging cupboards is a little tricky but once you understand the approach it's easy.. easier with SIP's than ICF's but still easy enough with either one..
ICF's are a tiny bit harder in that they have strips every six inches to screw sheetrock screws to . they're clearly marked and easy to line up so sheetrocking goes quickly with them too.
the real savings in SIP's or ICF's is from the money you save on heating bills. They are also notably quieter to live in. plus safer from a fire perspective.. (sounds counterintuitive but it's true.. I'll explain if you're interested)..
"I do like the three sources idea. Just not sure you've picked the 3 best sources."
Frenchy,
Wood heat is for the apocolypse on the pessimistic side, and for ambience on the optimistic side. It is a comfort knowing that I can use the woods around my house to heat it if the &*^% hits the fan or if I have an extended power outage or if gas prices skyrocket. Pretty dry indoor air, though.
Gas forced air is still relatively cheap around here if you're well insulated, running efficiently and turn it down to 63 each night like we do.
Electric mats are creature comforts, pure and simple. I dont like the idea of running pex to 2nd floor bathroom for morning comfort in tile shower and bathroom because hot water is not a quick on-demand type of heat 2 floors from the boiler, is it?
If I do only heat 100 SF in basement with radiant in floor, can I run it from the HW heater or would I need a boiler?
westmich,
I understand the fireplace issue. should be just fine.
My whole house 5500 sq.ft.) is in floor radiant heat run by a water heater..I've carefully done the energy calculations and I'm reasonably certain I'm right, in case I'm not, I do have those three back ups. Plus if I'm seriously wrong I'll simply admit it and buy a small boiler.. . We'll know the first 40 below day I have.. MY brother-in-law has a small boiler and he's recently shut it down and switched to a water heater with better results.. (not to mention lower energy bills).
OH I think I see what you're going for the electric heat for,, sure that will be fine.. some sort of timer to turn it off when showers are finished.
Have you decided on what heat recovery unit to buy yet?
You'll absolutely need one for a super insulated home.. it's not a nice feature, you have to have it..
One final point.. in floor radiant heat is not something nice. It's cheaper! we like our house to be warm and toasty.. normally I'd try to leave my temps at 70 but I'd frequently see them up at 72 or sometimes even higher. she who must be obeyed would clump around in boots etc..
Today the temps are at 67 and she's barefooted .. There is no outside temp or it's so low the weather man keeps telling me it's minus something..
Edited 11/30/2007 9:09 pm ET by frenchy
"One final point.. in floor radiant heat is not something nice. It's cheaper!"
To install, operate or both? I would love to have it whole house if affordable...
westmich,
To operate definately! To install again it depends on the HVAC contractor. I'm a do-it-yourself guy and I only know costs of material not costs of labor.
However from a material standpoint it's cheaper but not by much when you figure everything..
But labor.. it should be cheaper but I sure haven't seen that.. they normally command a premium.. I don't know why. I've done both and it's definately faster and easier to do in floor radiant than all the ductwork.. AsK NRTRob, he's agood guy who knows his stuff.
Edited 11/30/2007 10:57 pm ET by frenchy
Frenchy,
You claim that in-floor radiant heat "is cheaper to operate, definitely." In your claim, you are joining a large group of people, most of whom sell radiant systems.
However, researchers are not among that group. No reputable study has ever shown that radiant-floor heat delivery systems have contradicted the laws of physics. A Btu is a Btu, no matter how it is delivered.
The exaggerated claims of "greater efficiency" or "lower heating bills" -- take your pick -- are usually based on the idea that people with in-floor radiant heat voluntarily choose to set their thermostats at a lower set-point than everybody else. To test the hypothesis, Canadian researchers visited homes with in-floor radiant heat, and looked at the thermostats. It turns out that these thermostats were set at a slightly HIGHER setting than their neighbors with forced hot air systems. (The slightly higher setters were not statistically significant. But the thermostat settings were definitely not lower.)
Edited 12/1/2007 4:53 am ET by MartinHolladay
I agree that efficiency claims are overstated, and that the idea that MOST radiant purchasers are lowering their thermostats is untrue, 100%. The vast majority of my clients do report improved comfort, but I'm not hearing a lot about newly lowered thermostats EXCEPT in the case where they had truly horrible systems before. Personally I think most people live with a certain level of discomfort, and when they get to be truly comfortable, they just soak it up, rather than reducing heat output to match their previous level of discomfort to gain more savings ;)However, radiant does *typically* operate at lower temperatures that most other sources. That can, in many cases, directly translate into energy savings. Having to heat a boiler up to 180 whenever a thermostat clicks, for instance, then shut off and bleed all that heat out again before the next click is not exactly the most efficient boiler operation possible, but that's exactly what most hydronic systems out there today are doing.It does also reduce stratification over any convective or forced air method. That too can save some energy.Again, I agree it's exaggerated in the literature, and there are times that radiant will be LESS efficient than baseboard or panel radiators run at an equivalent temperature. Say, high temp suspended tube over a cold basement... but, if ultimate efficiency is the game, low temperature heating is a key tactic, and radiant can OFTEN be the a very good choice for that. Not always- but often.the only marketing claim that drives me further up a wall is the warm foot marketing. comfort is great, but those floors aren't always warm....
-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Although not related to cost, two big benefits to radiant floor heat for us is that the system is quiet, with no expanding baseboards making noises all night, and without baseboards or registers or radiators, you can put the furniture where you want it.
that assumes you get a quiet one, and you aren't a fan of big, thick oriental rugs ;)-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Martin,
I do agree that a BTU is a BTU, now let's apply that. The human body is warmed by the blood pumped from the heart. It stands to reason (and works biologically) that the blood furthest from the heart is the coolest.. Your toes are the furthest from your heart and thus they feel colder temps quicker than parts of the body near the core.
Heat works by simple princple, warm air rises, cold air settles (Think of a hot air ballon) with forced hot air the heat leaves the vents and climbs to the ceiling filling back in as it fills the room.. However physics still work. The cold air return is always at the floor level. that's because cold air settles on the flooor..
But wait! Our toes are at floor level. So they are exposed to the coldest temps in the room with forced hot air.
However with in floor radiant heat the floor itself is the warmest part of the room, it yields heat which rises evenly without the drafts of forced air. Without the stratification of forced air.
Let's look at your example. Was that a double blind test? Did both test subjects try both styles of heat on identical days? How do you know that couple a for example liked 72 degree temps while couple B prefered 68 degree temps? were the houses in identical situations regarding solar gain, wind, was the air exchange rating identical for each one?
Another words your test was invalid.. Too many assumptions..
I can tell you that I sit here typing this with a nasty cold, in a T shirt and stocking feet. the thermostat is set 67 degrees as the heat comes up from the floor. When my old house which had forced air the temp was usually at 70 degrees and on nasty days like today with a storm blowing snow around it would be at 72 and I'd be fully dressed likely with a sweater on definately with slippers or shoes on. Possibly with a blanket over my shoulders. (I do like things warm)
I don't sell in floor radiant heat, I used to sell telehandlers, those forklifts used in construction but as you know the housing crunch caught a lot of people out and I'm one of them.. (so if you've got a job, let me know) ;-)
Back to your BTU's it stands to reason that if your feet are warm the rest of you is going to be comfortable, Could some people have had the temps at a higher setting? Sure! But those temps would have been higher still if they had forced air..
Frenchy,it wasn't really a study in physiological comfort; it was more of a survey of households with radiant, where it was actually found that *in general*, people who get radiant don't turn their thermostats down. As I noted in my post, I think it's because they took "better comfort" over "cheaper heating", as once you've had the real comfort, you want it more. But, that's speculation. What is not speculation is that, in general, regardless of your experience or marketing, most people don't run lower temps with radiant. Perhaps partially because the biggest subsect of people getting it are people who are primarily interested in comfort, and who have the money to pay for it!Now, that's a fuzzy statement; some people are coming from houses where the thermostat might have read 72 degrees but the other, non zoned rooms were much cooler. Or maybe they had bad thermostats. Or maybe they moved from a leaky house with cold walls/bad windows to a new, tight house with warmer wall surfaces. In short, maybe they were previously compensating for other deficiencies in their thermal comfort with higher tstat settings and now they don't have to.Maybe they even stopped doing that steep nighttime setback and are now more comfortable at a cooler air temp because they are actually heating up the object in a room! In short, there are a lot of reasons that people might find a lower thermostat setting more acceptable in a new thermal condition than an older one. Having a radiant system may or may not be one of the drivers of that move.But most people still run their thermostats at 68 or 70 with radiant. do they have to? Maybe, maybe not... maybe it's psychological. But that is what the study/survey found.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
NRTRob,
well said..
Martin,
It's pretty hard to argue with your statement that "a BTU is a BTU" but one difference with a low temperature heating system and the right boiler is that temperature of the exhaust gas can be significantly lower than with a high temperature heating system.
If you output water needs to be at 130 F or whatever, then the exhaust is going to be hotter then that. If the output is 80 F then the exhaust temp can be, say, 85. Less money going out the stack.
Ron
Oh, and the fireplace is EPA rated and gets outdoor air--rated to heat 1500 SF (55,000 BTU)
Shelternerd,
The problem with forced air heat is that right at the floor is the coldest. That's where the human body is most sensitive to cold and feels it the most.
Staple up radiant heat is extremely cheap and easy to do compared to running duct work.
I found a system that makes putting infloor radiant heat a few hour project compared to a couple of days of ductwork fitting.
As for a air tight building the fastest, cheapest, way to achieve that is with ICF's
ICFs cheaper than studs and spray foam? Not in my world. What are you using on the roof/ceiling? I'm a radiant afficiando as well but we need AC so 15 SEER heat pump w/ spray foam is the best cost to value equation here in NC.55,000 sf house! Wow! ------------------
"You cannot work hard enough to make up for a sloppy estimate."
shelternerd,
Oops' 5500 sq.ft. sorry ;-)
Actaully here there are a few contractors willing to build ICF homes for stick built prices. Those not willing will only add a 2% up charge or they won't get the deal..
I've built with both ICF's and SIP's and it's faster to build with ICF's
ICF's are like leggos. plop them in place, spray the foam at the seam, and drop the rebar in place.. Next level! The heaviest thing you handle is the few pounds of the rebar.. The ICF weighs less than a pound and a can of foam is about the same..
I started on my home and wrenched my back badly (I was bed ridden for almost a month, nothing to do with building) my sister-in-law with absolutely no prior experiance finished it in a few hours. she did more than 3/4 of the work!
She got her directions from me when I was stoned on pain pills and slurring the words.. (I feel asleep about 3/4 of the way thru directions)..
When I finally found the right medicene and got up she'd done a decent job and I poured the next day.. (well I supervised the pour while one of the kids from the local grocery store did the actual pouring)
Based On that experiance I went hog wild on the front and bowed the foundation for the poritico.
We're talking easy stuff here!
SIP's on the other hand need some real effort to set up.. you have to glue everything together and then squeese it enough to get an air tight seal.. that's not easy! Towards the end I learned a short cut that made the work massively easier!
(It's still easier than stick building walls)
I bought SIP's directly from the factory and brought them home myself so I saved trucking costs.. (it helps that the factory was only 1/2 hour from my house)
I'd still use SIP's on the roof but I'd use ICF's right up to the roof line..
I'd also timberframe again.. just wouldn't double timberframe. too much work! who really needs a wall that's 17 to 18 inches thick anyway? ;-) Sure it's strong enough to meet railroad bridge requirements but who needs trains running on your walls?
Timberframing is astonishingly cheap!
All the wood I used 50,000 bd.ft. of hardwood like black walnut, white oak, cherry, maple, etc.. came to only $25,000.00 buy direct from the sawmill and avoid all the middle men.. I priced it at retail once and it was something like $850,000.00 worth of wood at retail.. Does that give you an idea of the markup in wood?
IT was so cheap that my subfloor is 2 inch thick planks of various hardwoods like tamarack, hackeberry, ash ,soft maple etc.. What would cost oh, say $20.00 bucks for a sheet of 3/4 inch plywood I bought for $6.40 plus instead of wrestling with a great big sheet of plywood I was setting down 2x12 planks, much easier for a fat lazy guy like me..
Cheap staple up radiant may be more comfortable, but assuming his heat load is wrong and that with all this superinsulation his loads are low, it's only going to be marginally more comfortable and it'll require an unnecessarily high water temperature just to achieve that.Now, radiant ceiling... that's cheap, low temp, and about the same in comfort, if you have flat ceilings. Still piping the slab, of course.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
NRT Rob,
OK we're in agreement with everything except the requirement for too high a water temp..
Won't the water temp requirements depend on the run of the tubing rather than anything else? I'll exagerate for clarity.
Let's say I have a tube 10 feet long and it yields up whatever amount of heat it will yield.
another length say 20 feet long will require more heat input and at the end won't exhaust at the same temp as the 10 foot length would.. Am I saying this correctly?
Once the exhaust temp drops below 90 degrees we're now in the point where it won't be comfortable. Aren't I correct ?
So to exhaust at 90 degrees the first tube might call for an inlet temp of 110 degrees while the second tube might call for 130 degrees..
above 130 we're at risk of trouble from what I've gathered reading about pex
I'm not trying to argue here simply clarify my own thoughts on the subject..
Everything is relative. What determines your average water temperature is generally two things: 1) the heat load, per square foot of emitter area (typically the floor, but could be ceiling/wall/radiator etc) and 2) the average conductivity of your emitter. for things like baseboard it's a little more complicated but that's the basic idea.For instance, if you need 30 BTUs/sq ft/hr, Warmboard might do that with 100 degree <b>average water temperature</b> while naked staple up tubing couldn't do it at any water temperature and tubing with heavy plates in the subfloor might need an average water temperature of something like 140 or something... all depending on finish floors, of course, which influence the overall emitter conductivity. The more conductive the emitter, the easier and faster heat can travel through it, and the lower the temperature differential between the water and the room required to push the correct amount of heat through the emitter.If you use a longer loop, you will get more of a temperature drop if you maintain the same flow rate, which will lower your average temp, and may require you to either up your flow or your supply water temperature to compensate, you've got that basic idea right. But that's just what you worry about AFTER you figure out the rest: a 100 foot loop of suspended tube is not giving up the same amount of heat as a 100 foot loop in concrete, if they are run at the same flow and even at the same average temp. If you ran them at the same supply temp and flow, the suspended tube would have the higher average temp, because it's not giving up as much heat and more heat is returning to the heat source instead of being emitted. But it still would not equal the output of the concrete at a lower average temp, and that's because of the conductivity of the emitter.Now.. with a very low heat load, the difference between all emitters does shrink though. If you only need 1 BTU/sqft/hr then practically anything will do it with a very low water temperature, for example. So suspended tube MIGHT be a decent choice here, <b>depending on the heat load</b>, which is always the X factor. If he's really at 30 BTUs/sq ft, suspended tube/staple up without plates won't even work, never mind work at a low temp. I don't think he is, but those are the numbers being thrown around.The 90 degree return, 130 out stuff is not accurate or really relevant. We have many warmboard systems running with 100 out and 80 return or even 90/70.. the floor surface is as warm as many lesser methods at higher temps. 130 would be VERY high indeed in that system.. but maybe needed under some carpets with high heat loads... whereas if you just hang pipe off the bottom of the subfloor, 130 isn't all that high. But your heat source might care and will certainly be effected by that choice.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
NRTRob,
Phewww! a lot there to digest..
OK if I put my pex into concrete because of the better contact, and conductivity of concrete a given length of tubing will yield more heat?
Similarly if I wrap my pex in aluminum and put that aluminum in full contact with a wooden floor I'll get the floor warmer than if I just staple it up, correct?
So my aluminum flashing with a bead in it to wrap approx 180 degrees around the pex will yield the same temps as your system? The difference being the relative heat load capability of flashing verses the heavy plates that you use, correct?
If I then use foil faced Icocianerate foam to redirect heat up I should be able to yield an acceptable amount of heat from a given temp of pex shouldn't I?
I think I understand your referance to a rug over the floor.. the rug adds more R value doesn't it?
However since heat is only slowed down, not lost. Won't the rug eventually stabilize at whatever temp the floor will be at? Let's assume the floor was at 95 degrees, at soime point won't the rug achieve 95 degrees?
a certain thickness of metal can only conduct a certain amount of heat. So a thin light plate with some less conductive silicon in it is NOT equivalent to a heavy gauge, tight fitting plate with no silicon. It will be somewhat better than no plate at all, however. I don't ever rely on reflectivity to do the job conductivity should do. conductivity is nearly forever. Reflectivity... not quite as guaranteed. But short term, sure, it will help. Is it the same? no. But it may help.If you add R value to the emitter (lowering its conductivity), you slow down heat transfer. Restate that: you get less BTUs through the rug per hour (your heat transfer rate is slower). That means your BTUS/sqft/hr goes DOWN if all other parameters stay the same (average temperature difference, etc). If you change nothing else, the "new equilibrium" will be a colder room: -the temperature of the room drops, because your heat gain is now less than it was,
-Lower room temperature then accelerates the rate the transfer from the water (you have a wider temperature differential between water and room... temperature differential is the second part of the heat transfer equation)
-Room Heat load drops as its temperature drops, getting closer to the temperature of the outdoorsEventually, that rate of transfer balances with the new rate of heat loss of the room at it's . When heat gain = heat loss, room temperature stabilizes.Heat is not lost; it just goes back to the heat source, un-emitted. Your heat source heats up faster and shuts down faster perhaps. But regardless, what does NOT happen is the heat is NOT emitted into the space as fast, and unless you fix it by raising your average water temperature to drive that heat as fast as it's needed through your new, more resistive emitter (with a rug), then your result will be a colder room, if your initial water temperature was correct.Imagine wrapping your pipes in insulation. all of them. Your zone may call all day long, your boiler will stay hot (assuming a boiler), trying to get its heat out, but the pipes are just not emitting enough to satisfy. Are you running efficiently? So no, the floor will not stabilize at the same temperature, unless you increase your ability to drive heat through your new, more resistive emitter. This means running the zone longer, if you were already running water hot enough for this, or raising your water temperatures to drive the heat through the rug faster. Or, I suppose, if you reduced your heat loss you could attack the "other end" of the issue.Hope that helps?-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
NRTRob,
yes that does a lot more than I asked, Thank you I appreciate your answers and your efforts at translating things into terms I understood..
Martin, if you were building a home for yourself today in Michigan, and you had the budget for either RFH or the best insulation package available, it is evident you would do the latter. And how exactly would you insulate it to get the best bang for the buck?BTW, my builder suggests this (below), on 2x4 exterior wall construction of a 2-story home. I think local code is a joke for insulation, and we should meet a higher standard, but am not sure how to best accomplish it. -rigid foam under slab, on outside of poured knee walls and on exterior walls over the plywood
-blown in cellulose in rest of house, "to code"
-bats for between walls and under floors where sound dampening is desired
Westmich,
Big question; no short answer. How much you want to invest depends upon how long you intend to live in the house; whether you believe that energy prices will rise steeply, gradually, or will stay the same; and whether you care about global warming.
To be flippant, I could say that you need at least twice the R-value as the minimum specified in your local code. But that would be unscientific of me. Only you can answer the question, based on your own needs, beliefs, and priorities.
Personally, I wouldn't build a concrete slab in a cold climate without at least 4 inches of XPS under the entire slab; 6 inches would be better.
Martin, the 6" of XPS under the slab, are you referring to the sprayed foam? Is that sprayed into a form and trimmed flush, or doesn't it matter if there are peaks and valleys when the slab is poured (thinking about uneven surfaces cracking)? Would 2" rigid foam x 3 layers do the same thing?
Westmich,
Already answered -- see post 15 in this thread.
The matter of how much XPS to put under a basement slab interests me. At some point, so little heat is being lost that cutting it further isn't worth the cost, in terms of absolute BTU/hr saved. For an "ordinary" house (just to code), 2" of rigid foam cuts the loss to ground to a small fraction of the total heat loss for the whole structure when it's zero (British degrees) outside. For a superinsulated house, that same heat loss could be worth chasing, calling for more XPS under.Quantifying the loss, so see the BTU/hr savings vs. extra insulation, should be fairly straightforward: Q= (Area * temp diff)/R. The R is easy; for XPS it would be 5.0 times the thickness in inches (ignoring the R of the slab, about 0.02 to 0.03). The area is that of the slab. I'm ignoring for now edge effects, which can complicate matters. But what should be used for the sub-insulation ground temperature?Down around 6-8 feed below the surface, the seasonal temperature swings are greatly damped out, and don't swing much on either side of the average temperature of the surface through the years. However, with an insulated slab above the soil underneath it, there is no direct exposure to either the 90 degree peak summer temperatures or the zero degree winter night temperatures. I would think that after a couple of years the nearby soil would be perhaps a few degrees above the deep soil temperature. In mid-New England, I would guess this would give a soil temperature around 50 F within a couple of feet below the slab. Yes? No?For a slab footprint of, say 1500 sq.ft., 2" XPS (R10) under, and a temperature difference of 70-50 = 20, the heat loss would be a rather constant 3,000 BTU/hr. That might be less than 7-8% of the peak heat loss for the whole house if it is ordinary, but over 15% for a superinsulated house (depending on its size and what constitutes "superinsulation in this case). It all adds up, they say. So for the latter house, adding more XPS under could pay off.A fixed heat loss of 3000 BTU/hr, over 213 days (assuming May-Sept are warm enough so the loss is of no consequence, covered by normal electrical use, solar gain, etc) gives 15.3 million BTUs, or about 4500 kwh. For electric heat at 12 cents/kwh, that would be $539. Even with a GSHP, with COP=4.0, that would be $135. The material cost to double the XPS to 4" (assuming $28/sheet 4x8, 2") would be about $1300 (19 years straight payout). I hope I haven't screwed up any of the above calcs. Someone will let me know, I'm sure.One could argue that the soil will add to the R if there is no water movement through it. I could use, say, R=0.1/inch (a bit better than for concrete?) times perhaps 12-36 inches (??), which would add 1.2 to 3.6 to the R10 of 2" XPS. These assumptions are rather crude.Martin, do you have any better ways of doing the slab heat losses?
Thanks. That is both intresting and educational for me.There are couple of figures that I would suggest need orrection.
One is that the average soil temp in NE runs a pretty steady 54-57°F at a depth I am not sure of, I believe about 6-8 feet. I know it is not hard to maintain an unheated uninsulated cellar at at 55°.YThe other thing that strikes mme as something to consider is in a radiant slab, the slab temp would be 85-90 degrees, so your differential there would be say 85- 55 or thirty degrees or so.Of course all this ges to cost more than comfort in my mind
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Your mention of warmer infloor heat in the downstairs is the similar set up we have here. The 1st floor is built into a hill-bsmt ht at the back, steps down to full above grade at the downhill side. All slab down there with ceramic-radiant infloor HW.
Second floor has no general heat-in floor w/ceramic in the baths, open area from downstairs at MBR and hall to other 2 BR's. 2 remote BR's have a 4' HW salvaged old fintube basebd.
Plenty comfortable down which houses our LR/DR/Kitchen and mudroom/Laundry/manshower. Plenty comfy up in the sleeping rooms.
Layout and use of the house should figure in on the design of the heating system. Wonder what the OP's layout is?A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Piffin,
You wrote, "The average soil temp in NE runs a pretty steady 54-57°F at a depth I am not sure of, I believe about 6-8 feet. I know it is not hard to maintain an unheated uninsulated cellar at at 55°." That's certainly not true here in northern Vermont; I know from personal experience. Most houses have a furnace, boiler, or water heater in the basement; these appliances give off a lot of heat, preventing the basement from freezing.
I built my own off-grid house in 1980; still live in it. Many of my friends built similar houses at the same time. I have no appliances in my basement -- no water heater, furnace, or boiler. (I heat with a wood stove in my living room.) My basement walls are basically uninsulated. I paid attention to air sealing, using 1980 methods (sill seal) at the time of construction. When the outdoor temperature drops to -20 and stays there for a few days -- you may know the weather I'm talking about, when the thermometer rises to zero by noon and then starts dropping -- my cellar is at risk of freezing. I have water pipes down there, so I keep close track of the situation. When necessary, I fire up a small propane space heater to keep my pipes (and potatoes) from freezing.
All my other off-grid neighbors with similar basements experience the same phenomenon.
You are definitely further north and at a higher elevation. I am at 88 feet above sea level.Used to live at about 8000 feet in CO.Do you know what your average ambient soil temp is?I hope I am not coming across as adversarial. I am learning a couple things fromm you.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffin,
I'm at about 1750 feet. Our ground has been snow-covered for a couple of weeks. The snow usually melts in late April or early May.
I haven't measured the soil temperature. I know that the soil temperature keeps dropping until May or June, when it slowly begins to rise. Frost can go down 4 feet or more, depending on snow depth; so, at certain seasons of the year, it's not impossible for the top half of a basement wall to be exposed to temperatures that are colder than 32 F.
Martin,
You could probably measure your subsoil temperature in the next five minutes if you have a deep well.
I have just measured the temperature of the concrete floor under my feet. It is at 21C (70). The output temperature at the boiler after the mixing valve is 26C (79F) and the air temperaure at 5'0" from the floor is 20C (68F). The outside temperature is about 2C (36F). The floor does feel cool, but it is certainly not cold or uncomfortable in the least.
Ron
Ron, how do you heat your home and where do you live?
westmich
I live in Nova Scotia and heat mainly with an low mass oil burning boiler. We burn a bit of wood, too. The boiler is a Toyotomi Oil Miser which the supplier told me was one of the few on the market which would not be harmed by short cycling. It's hard to find an oil burner small enough for a house like mine.
Two levels of RFH in concrete and one with fin baseboards. About 2600 ft sq on these three levels and our annual heating cost is half the cost of our telephone/internet bill.
The Nova Scotia climate is quite moderate. Nobody really needs air conditioning because of excess heat unless they have designed themselves into that need. Winter temperatures on the Atlantic coast, where I live, seldom hit -20 C (0 F) and if they do, they don't stay there long.
Ron
I'd like to get my utilities to match my phone bill, but I'd be happy for a hundred a month for heat in the winter. Went to Nova Scotia and Newfoundland last summer for 3 weeks, great trip. Father in law just shot a moose a couple weeks ago in Newfoundland and I just made stew. You live in beautiful country.
This is getting more interesting each day. I invite any and all comments on part or all of this very long post. I know there are threads that address these issues, so my apologies for re-posting them to this group. But you are familiar with the current thread and I am confident I am doing you all a great favor by keeping you up to date! (ahem...)
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Today I met with builder and HVAC + insulation team to address the issues we have been discussing these past dew days on this thread. The HVAC contractor and insulation guy made a compelling case for tight envelope via spray foam (combination of closed and open cell), and Mr. HVAC presented his goals and performance specs. He would not spec the exact equipment without a confidentiality waiver because he doesn’t want me or the builder to shop his personally designed plan to other contractors and steal the secrets he has developed over time. I have no problem with that (but wait till you see below what he charges for that expertise). He had studied the plans for several hours and did a careful analysis of heating and cooling needs, energy use, etc., comparing standard code-based insulation vs. the spray foam insulation package, and presented them in a spread sheet. He also gave the following performance guarantee for his system, using natural gas forced air:
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-Indoor temperature variation: +/- 2 degrees F; -relative humidity: 20-30%; -air filtration: <.5 microns; -fuel utilization: >95%; -ventilation design criteria: >.33 ACH; cooling efficiency: >13 SEER;
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All of this based on Building Envelope design criteria of: ASHRAE standard 90.2; wall and rims standard: Uo<.030; Foundation: Uo<.055; Roof: <.023; Windows: <.036; Floor: <.055; air infiltration: <.01 natural air exchanges (<1.0 at test pressure).
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With the tight envelope, he says smaller FA furnace and A/C unit not only can be used but SHOULD be used for maximum efficiency, comfort and performance. He said that traditional HVAC contractors would look at his 90,000 BTU furnace he will use (based on his calculated peak load of 43.8 with spray foam) and say not nearly big enough, because they are not used to having such a tight envelope and highly regulated humidity control and fresh air exchange. The ERV vents the bathrooms and kitchen, and has its own duct system. He says smaller A/C unit needed (based on calculated peak cooling load of 21.9) so it will run more and therefore dehumidify better; he also documented the increase in electricity use because of this. IT is a pittance compared to the annual Nat gas savings estimated (about $100/month less than standard insulation).
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He is a certified govt tester for blown door testing and infra-red thermography, and he does that testing before the drywall is installed so they can fix areas where needed. He seemed very knowledgeable and I trust what he says to be true.
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The stated advantages are more comfortable living spaces via equal heat and cooling distribution as well as reduced energy consumption, both of which any reasonable person would have a hard time protesting.
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What I can protest is that for a 2-story (2500 SF) plus walkout, they want 15,500 for the insulation package and 23,000 for the forced air HVAC (and high-efficiency wood burning fireplace in living room). Now I respect the heck out of what these guys do for a house, the environment and the continued advancement of the trades, but do these costs seem a bit extreme to anyone else but me? I do not have the budget for both, and I’m not sure I would pay the seemingly astronomical HVAC cost if I did have the money just on principle.
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Anyhow, I am leaning toward the whole house foam package (after a couple more bids), and am still on the fence for which HVAC method to use.
you didn't look at the links for the RFH ranchMike Smith Rhode Island : Design / Build / Repair / Restore
Mike, I did, I looked at both links. In fact, I spent the better part of an hour right when you sent them. Did I miss something that would make it seem I didn't see it? I hope I didn't miss the whole point of the link...
Westmich,
I haven't done any calcs, but my seat-of-the-pants reaction is that a 90,000 Btu furnace sounds oversized for a 2,500 sf superinsulated house.
west.... i'll check some of my costs but this seems like the outer limits
<<<<<What I can protest is that for a 2-story (2500 SF) plus walkout, they want 15,500 for the insulation package and 23,000 for the forced air HVAC (and high-efficiency wood burning fireplace in living room). >>>>Mike Smith Rhode Island : Design / Build / Repair / Restore
Mike, it's interesting you say 90k btu might even be too large. That gives me some confidence that The HVAC contractor/rater who quoted me the huge number of 23k said that if I go to anyone else in town they'll tell me I'm nuts, that for 2500 SF plus walkout they'll suggest at least 120k btu. Maybe his understanding of things is not as unique as he thinks. Then again, my perception is that this forum is not exactly full of novices contractors, and may not be a representative sample of contractors I'm likely to encounter.
"west.... i'll check some of my costs but this seems like the outer limits"
when you say "outer limits", doe you mean upper end of realistic estimate or outer limits of the galaxy?
> that a 90,000 Btu furnace sounds oversized for a 2,500 sf superinsulated house.Agreed. For super-insulated, I've found the mean to be closer to 12,000 btu/h per 1000 sf, or a third of what was speced.
Let me chime in with a third confirmation, just to drive it home.I'm impressed with the contractor's understanding of the principles involved, and he's dead right on the stuff that was relayed here as far as sizing principles, but a truly well insulated home should be coming in at no more than 10 to 15 BTUs/sq ft on average. 30BTUs/sq ft is indicative of a poorly insulated house or those two story glass walled great rooms.The contractor is probably STILL right about the other contractors in town though. The level of oversizing out there is truly saddening. I'm happy when I see a boiler installed that is less than twice the size it needs to be.I also want to note he is not pricing a "smallish FA" system. he's quoting extraordinarily high efficiency FA, AC, filtration, and air exchange. It might be high still, but don't minimize what you are being offered.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Dick,
There are many ways to calculate heat loss, using pencil and paper or software. I haven't double-checked your figures.
Suffice it to say that calculating heat loss is only the first step; the second step is to make a prediction about future energy costs. For someone who believes that heating oil may rise to $10 a gallon, or even be unavailable in a future energy crisis, the value of extra insulation will be different than for someone who believes that the price of energy will increase at the historical average rate for inflation.
Some builders are attempting to build houses that use only 10% of the heating energy required for buildings complying with current building codes. This allows for significant reductions in HVAC equipment. The levels of insulation involved are high -- I have reported on houses with 12 to 14 inches of rigid foam under basement slabs. Many people scoff -- they whip out their calculators and point out that the builder has spent thousands of dollars to save a small amount of energy. True. Only time will tell who is laughing in 20 years.
I have gone back to the beginning of the thread to read the early posts again between you, Piffin and a few others, and I think I found the answer right under my nose:
If you only have the up-front budget to do either in-floor OR superilsulation, do the insulation with proper properly sized and installed HVAC. The basement floors and other areas of the house will be much more comfortable than in a home insulated to code, even with forced air.
The great insulation can come in many forms (SIP, ICF, spray foam, even cellulose) as long as enough insulation used is installed properly and the house is wrapped properly and blown door tested for leaks and thermographically tested with infra-red.
With a bigger budget I would do all RFH and ICF+SIPs, but since my $$ is limited I think the higher spend on insulation will win the day, then get a real pro for the HVAC needs.
Martin, I agree with you, I installed the Owens-Corning Warm-N-Dri 1-3/16 compressed fiberglass panels on my exterior foundation wall from footing to sill and then used a thick latex sand paint to give the above grade panel a stucco look. I then installed 2" of R-Control styrofoam board treated with insecticide under my basement slab, with a 1" R-Control strip isolating the slab from the foundation wall.
Today it is 19D's outside, my unfinished basement is 69D's, the only heat source is indirect from the furnace, my walls are warm to the touch above grade level and I can walk barefoot on my floors comfortably.
A spray foam contractor I had talked to had advocated spraying 2lb foam over the basement gravel which would have been quick and easy, but because of cost I decide to use the R-Control. The only issue was that the gravel had to be dead level and cutting the panels left thousands of little white beads everywhere :-0
My HVAC contractor had tried to talk me into a bubble/foil layer (LOL) and radiant heat, but thanks to this website and FH members, I decide to put the money into other things like cabinet upgrades and trim.
Today it is 19D's outside, my unfinished basement is 69D's, the only heat source is indirect from the furnace, my walls are warm to the touch above grade level and I can walk barefoot on my floors comfortably.
Bigman, that's pretty impressive and really speaks to heart of the the initial question on this thread (I am the OP): if the foundation and rest of the house are insulated well enough, can you have a comfortable basement floor without heating the slab?
Have you lived there long enough to know what the basement slab and walls are like at 0 degrees F or lower?
Why the r-control under slab vs. blue or pink board?
Jim in Grand Rapids, MI
Why the r-control under slab vs. blue or pink board
Price. EPS is cheaper. The R per inch is slightly less, but the foam is cheaper.
If you are close to a R-control plant you can buy direct and they will slice to shatever thickness you want. They will deliver free if you buy enough, but it's a bunch.
I think you're seeing the best money spent is insulation. Put it under the slab. Once you pour there's no going back. You can use Type II under slab, it will do the job.
Joe H
we get our R-Control ( Performguard ) at Branch River Foam
i can order it in any density from 1.0 to 2.0.. under slabs we usually use the 2" 1.5/lb/cf it's strong enough so it doesn't break when you walk carefully Mike Smith Rhode Island : Design / Build / Repair / Restore
If I get it correctly, it is basically a 1.5" wall inside the exterior framing wall.
See if I undesyand the benefit: The finished insulated wall only loses heat from inside where the horizontal 2x strips meet the 2x4 framing cunducting heat to the outside, rather than along the entire vertical stud without teh mooney wall?
Mike, you ever hear contractors balk when asked to do a mooney wall if they've never done one? I could see sheetrockers getting cranky every time they shoot for the stud 16" OC and miss a mooney, eh?
framers might... but they get paid for it.. so.....
sheetrockers don't care.. they can see their target
you do have to make sure there's no bridging so you wind up
with "nail pops" ( which nowadays are "screw pops " )
i figure our 5" Mooney wall is a true R-18 including all the studs & framingMike Smith Rhode Island : Design / Build / Repair / Restore
If I get a decent enough price I am leaning toward all sprayed foam in the entire house. It seems like it handles very well most or all of the issues discussed here, ICF and SIP construction notwithstanding.
Is there a way to cover the inside of the studs with the spray foam to avoid thermal bridging without using a Mooney-type wall and still install the sheetrock effectively? I will discuss the Mooney with my builder tomorrow, but he may want a limb for it since it's learn as he goes...
By comfortable I mean it is not a shock to walk across it, I would not spend the day barefoot on the floor (to hard on the feet anyways!). This will be my second winter in the new house, I have checked the foundation wall several times over the course of the year and have not noticed a big change.
Anybody have any inexpensive ideas on checking the temp of the floor and walls?
I used the R-Control because of Mike Smith's experience and I respect his opinion, I used the 2" 1.5lb just like he said, the R-Control is supposed to be treated for ants and termites, where as the pink and blue board on not. Google termites and styrofoam and you will be shocked.
This winter I will be finishing off 1/2 the basement for a rec room/home theater. I have already started by laying Delta-FL on the concrete, covered with 3/4" Advantech (I got a good deal on it) secured with Tap-cons.
I plan on steel studding all the walls with a 3" gap from foundation wall to stud, I do not intend to insulate the interior side of the foundation, I figure an air gap will work just fine and allow the space to be ventilated to the unfinished basement.
Bigman
They sell infrared thermometers that you just pount at something and it takes the temp.. I use it to check the temp of my ceiling 18 feet above my head. Not terribly expensive either..
First, I don't see any real advantage to spray foam under a slab instead of regular rigid foam. But I don't know the structural issues involved either.
A well insulated basement slab, in a well insulated basement, goes a long way to comfort. It won't "radiate" any heat because it's not a heat source. However, as long as it can pick up heat faster than it can lose it, it will stabilize at about room temperature. Or, room temperature at the floor, at least... if you use FHA, stratification might make it slightly lower than room temp. This assumes NO SETBACK IS USED. Setback less the mass cool down and this is a very weak way to pick up that heat again. Comfort will only be maintained with a consistent room temp.
Room temperature surface on the floor isn't particularly warm, but it's not very cold either. It's cool, but fairly comfortable.
Adding radiant heat only adds a few degrees to the floor temp in that case if those loads are low. However, slab radiant is very cheap as well, so maybe it's worth it. This being a walkout basement, the load will be higher than it would be if it were a full buried basement though, so the difference might be more noticeable; floor temperature is a function of heat loss. Higher the load, warmer the floor.
As with most questions regarding heating systems, the final answer is in the heat load calculation.
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
well, Michigan is not Rhode Island..
and the yuppa is not Detroit..
but it ain't that bad...
some are advocating super insulation.. i lean towards that myself..
but
in your case i'd be looking at 2" XPS ( with borates ) under the slab
1" XPS on the concrete walls with a 2x3 or 2x4 stud wall ( for electric devices & drywall base ) blow the walls with denspak cells
pay special attention to the floor joist box... again DP cells with dams
triple glazed windows are problematic in life-cycle costing..... be sure your window mfr can actually deliver a product tha is going to last for the life of the house..... most triple glazed units do not have a good track record for durability
nothing like looking at a $ replacement cost 20 years from now that could be avoided
in the attic i like the R-60... and it's easy to get and inexpensive
if you do those things.... like Halladay said... your heating source becomes secondry... but think about ventilation, humidification, dehumidification and air conditioning
a tite , super insulated house needs a good plan to stay healthy
westmich.
Do I understand you correctly? you're building new?
I'll skip on answering the question you asked.. others have stated their experiance and preferance and My comments won't add any clarity..
I will ask you if you've considered alternative to stick building?
I mean SIP's or ICF's
If you do you'll find that they offer vastly superior insulation over stick built with either cellulise or sprayed foam.. You'll find reluctance from tradional contractors who have decades of experiance with stick framing but none with SIP's or ICF's. However here in Minnesota contractors are currantly selling ICF homes for only a 2% premium over a stick built home and some are agressive enough That they will build for the same price..
OK Here's the potential savings..
My old house was well insulated before I tore it down.. it had a good vapor barrier and carefull attention to sealiing.. It was about 2500 sq.ft.
The new house built with both ICF's and SIP's is about 5500 sq.ft. and uses the old furnace (untill I finish the interior when I'll have in floor radiant heat). the old furnance was a nearly new High efficency unit that I reused.
So I have about 3000 more sq.ft. well in excess of twice as many windows, the old furnace and yet my heating bills area 1/4 of what the old stick built house was.
My worst two months (Dec. Jan) were $500.00 each. Now they are about $120. Last year my heating budget was $2000 dollars cheaper than my old stick built house..
Because I'm busy building this place I haven't spent any time tightening it up. I know several places where cold air leaks in.. Simple to fix but I haven't gotten around to the small details yet.. I expect to save further once it's fully tightened up.
I realize that sounds rather extrodinary but it's similar to others I've spoken to.. spray foam returns some of that savings but you still have a thermal bridge every place you have a stud.. many places studs are doubled up or more and that can be a lot of area with no real insulation.. That's why for energy calculations they use a figure of 80% of a walls normal rating.
Great comments, thanks. I have been looking at SIPs for years, but you're right--my builder does not have much experience with them. I asked him about them when we first met several months ago and he said he could do it but the up-charge woudl be in the neighborhood of 20%, I think because he isn't confident he can cost that part of the job with any reliability. Now that I'm looking at an additional cost of spray foam vs blown cellulose (another 9k or so) it may actually be in the ballpark to look ar SIPs again.
If he already has his crew of carpenters and they are not very experienced with SIP construction (just guessing they aren't), am I asking for trouble going down that road with them?
Also, since my plan is already done and we have the project down to the penny (yeah, right) except for the insulation and HVAC decisions, what sort of time would one anticipate for a SIP framing design, cost estimate and delivery were we to venture down that road now? I am willing to delay a bit, but this house needs to be done by mid to late May for the Spring parade of homes so we don't have that much time to wait...
" am I asking for trouble going down that road with them? "A lot depends on his attitude.
If you have to drag someody kicking and sceaming into the twenty-first century, it WILL cost you more in aggravtion than it is worth, but if he is mature and willing to grow and learn, both of you can benefit
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We'll see tomorrow which category he fits into!
Where does one start for SIP design and estimate? Are there regional dealers or local or what? Do I go to the building supply outfit where the lumber package comes from or go to a SIP specialist?
In the mean time, I will search old discussions for SIP information.
There are dealers here for SIP. They can take my plans and rehash them for their product in a few days for a basic home, longer if it gets unique in shape. They are likely with some styles to suggest minor altrerations that would make the product work better or sizing that would be a more efficent use of the materiaals.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
westmich,
It honestly depends on the attitude of your builder. When he suggested an up charge of 20% he was doing everything to discourage you that he could in my honest opinion..
Therefore I believe that you will most likely need to find an alternative builder who can give you a far more competitive quote. Then if you wish you can offer this builder a chance to meet it and learn or go with the alternative..
I don't know if the time will allow you that option..
What I found as I explored the option of SIP's and ICF's was that no-one I could find had any real experience with them and were padding their estimate heavily to compensate for the privilege of learning on my dime.. I did the research myself and found the cost of the materials were actually slightly less than the total cost of stick building and adding insulation packages. Since no-one had any experience I choose to do-it-myself (with a twist)
Having built with both ICF's and SIP's now I can say that if I were to ever do this again, I would use the SIP's on the ceiling or roof again, but I would use ICF's up to the roof line.. The reason is ICF's are fast.. faster than stick building faster than building with SIP's and the slight loss of insulation you get when you use ICF's over SIP's can easily be over come. While the advantages of ICF's over stick building are massive..
Here In Minnesota SIP construction is still relatively rare and those with experiance are charging dearly for it.. However the cement companies are doing a lot to excourage the use of ICF's and are providing free training to those who will select them.. . There is now a big enough core of builders out there willing to compete at a fair basis for those ICF houses that 2% is the up charge while some builders are willing to build at the same cost..
One final point..If you find the right builder you could build using timbers in addition to SIP's or ICF's for a relatively modest charge.
I realize that sounds foolish but I did it.. If you go to the archieves and enter in 85891.1 & 94041.1 you'll see my home.. It's about 5500 sq.ft. of double timberframe using white oak on the inside timbers and black walnut on the outside timbers..
I used 50,000 bd.ft. of hardwood building this house and spent only about $25,000 dollars for enough wood to build the timberframe parts inside and out, the trim and all the interior parts the cabinets and flooring etc.. Another words I spent about $25,000 to build most of my house!
There is a "trick" to that and you certainly won't be able to do that with the average contractor.. Plus while the cost of my materials was modest I did all the work it took to prepare them for use.. I'm not sure with the cost of todays labor that youi could do as I did and still reduce your costs.. I do know that the use of some timbers inside would be a relatively modest cost to the right builder.. If you'd like I explain the pluses and minuses of those..
Here's a new one for you. Do the whole house with radiant heat. Everywhere! It is the best feeling in the world to walk into a room with radiant heat on a cold day. How you'll really notice is when you go from your nice warm, comfortable basement, to your upstairs with regular heat. It's like, "wow...why didn't we do radiant up here!" The dog will be in the basement laying on the floor, your kids will be down there, laying on the floor. Listen to me Westmich....do the whole house! dvc61
Listen to me Westmich....do the whole house! dvc61
dvc61, are you just causing trouble now? ;-)
I would love to have it in th whole house if it were in the budget. Not many people do it in west Michigan that I am aware of, so the prices are still very high. Just curiously, if you were to a do whole house in RFH in your area what would you expect to pay (1400 sf main floor, 1100 SF upstairs, 1400 sf basement).
Rigid foam under the slab.Pipe the slab (0.50/square foot or so? 0.75? cheap).If you can do/want to do radiant later, you're ready for it. But NEVER EVER skimp on insulation for a heating method. That's just dumb.However, The question is whether the spray foam REALLY IS improving your insulation under the slab compared to (presumably cheaper) rigid foam.I say, no it's not. do 2" of rigid foam. See what that does for your budget. You still might do both.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
I like the idea of superinsulation in this climate regardless of heating method, as well as laying the PEX into the slab. The latter sounds inexpensive enough to do--if it only costs .75/SF, I can assume 750- for 1000 of basement. Does that number include labor, as you state it? Where, then, am I spending the other 7000 for the full job--is it for the boiler, a few other parts and the labor? That seems like a disproportionate cost division between laying the trubing and trhe rest of the job, but maybe the PEX is just that cheap to buy and lay across the ground in purdy little curves...
I have not seen the bid from the heating contractor to know if he intends to use the nat gas HWH or a separate boiler for use in the basement floor.
I am meeting with the builder, HVAC person and the insulation person in the morning together in the same room (the insulation and HVAC contractors are from their own companies but often work together to match insulation with heating-cooling-humidity-fresh air needs. What questions do I need to have answered by each person?
labor is not included in that estimate. but pex in concrete is very cheap to procure and install; the rest of the system, however, may not be cheap. It's not expensive to hedge your bets though and as a fairly biased person, it kills me to see concrete poured without pipe in it. I would ask for pricing on a tubing install only for the basement from the HVAC guy.I would ask for pricing on 2" rigid foam plus vapor barrier for under the basement slab and on the vertical edges of the slab from whoever would do that work.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
NRTRob, as I get ready to install PEX under the basement slab and perhaps under the garage slab, I have a couple lingering questions.
1. I think you wrote me a while ack not to exceed 270-foot runs. Is that correct?
2. Should I aim to have all of my runs equal length? Why does or doesn't this matter?
I am planning to use 1/2" PEX and staple it to the foam board with the foam staples.
Many thanks!
Aim for 250, and get the rolls in 500' or 1000'. Some pumps don't play nice with runs over 250'. Shorter loops are ok.
I sized a pump for 4 - 1000' loops of 1/2" . IIRC it was a 4" pump.
Equal lengths is best, the system is self balancing. Usually flow rates and heat transfer will be the same in each loop.
Edited 1/17/2008 11:36 pm ET by rich1
Edited 1/17/2008 11:38 pm ET by rich1
Rich1, thanks for the reply. I think I can get 3 equal runs and cover the area very well.
we generally try to zone by zone valves.this means we are generally trying to flow balance the whole system.Thus, even if we have one zone of 3 equal lengths, I would personally use flow meters on the manifold for those loops, to make the entire system balancing either. with flow meters and balancing valves, equal loop lengths are irrelevant. I would ALWAYS rather see you isolate different rooms rather than equalize loop lengths as well, if there are multiple rooms here.If that is not what you are doing, then you have more options.In a basement, loop length requirements can vary wildly depending on the rest of the system. We often hit 400' loops in basement. But if you want to be absolutely sure you are not causing any problems, 250' is a pretty safe loop length in almost all house heating cases.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
RobWhat are you using for flow meters and how much are you paying for them? Michael------------------
"You cannot work hard enough to make up for a sloppy estimate."
practically all major tubing manufacturers have manifolds with flow meters, and as far as I can tell there are only a couple of flow meter variants out there.We use Mr. Pex systems. Pricing, well, that's confidential don't you know ;)-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Boiler, manifold, mixing valves, controls, design, installation....
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That touches on a thought perking in the back of my head.It has been demonstrated that water flowing through soil will rob it of heat far faster than simple radiat heat loss. The water carries heat off in a sort of f;luid convection current like leaving a window open.So I would postulate that in soils and conditions where waater might be running under a slab, the sprayed foam would perform better than a foam panel where it allowed moisture to surrond it and move on.Of ourse, there are structureal and other reasons why we do all that we can to eliminte this likelihood by providing poroper drainage, but we all know tht it still exists in mmany places and many individual homes.
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I don't understand your theory.Why, exactly, would rigid foam be rendered less effective by wet soil?Perhaps some small areas would perform less, but I don't believe that is the case for most rigid products, nor for the vast majority of the area under the slab with rigid insulation.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
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"Why, exactly, would rigid foam be rendered less effective by wet soil?"All the gaps and cracks between panels. Also the smooth surface between panel and crete would allow for easy passage of water while the irregular surface of sprayed in place foam would be less likely to.
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Yes, but Piffin... you're pouring concrete on top of it. That's concrete, on top of it... not much room for water to get "in between", certainly not to get "in between" and move much.You might, possibly, maybe get a small amount of movement in the cracks, but it would have to be pretty small, and represents a commensurately small amount of heat loss. Certainly nothing near the amount i would expect you'd need to justify the (ASSUMED, I have not priced this) cost upgrade of going with spray foam under the slab.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
It was just a thought, not an argument
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gotcha. just hold on a sec while I climb back out of your throat... there we go. Man, you brush really well!-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
westmich,
I'm not totally sure what it would cost per square ft, as I did most of the installation myself. A friend helped me run the tubing from my furnace area to the room I was converting into a den, which was a garage before. We poured cement on the tubes and had a plumber hook up the manifold etc at the furnace. The manifold and the labor for the plumber was around $1000.00. Admittedly the labor in my area is unreal, but once again I'm telling you to look into it. Get some estimates. Maybe you'll see it's not so bad after all? Even if it is initially more.....it's so worth it. It is the most comfortable room in the house. Heat from the bottom up. Heat down where people live. Consistant temperatures, no drafts, no dust being blown around. No baseboard to interfere with furniture. No baseboard (UGLY!) to paint or dust. No slippers in Michigan in the winter....how about that! I'm from Ohio and I know about cold. Stretch to do it!!!! I hope the trouble I get you into is worth it!
dvc61
Rubbish.
The comfort of radiant heat comes from the floor being warmer than the air - not the same temp!
Insulating the slab is a fine idea, and the two ought to complement each other.
I doubt the contractor has ever lived in a place with radiant heat.
I just walked into this long discussion and haven't read through the many posts, but your insulation contractor is just looking for work.
Whether it makes sense to install RFH in the slab depends on how you plan to use that space. Since it's a walkout basement with a finished floor (tinted concrete), it sounds like it has the potential for living space.
My question is: why consider RFH in the slab and FHA in the rest of the house? Are you planning to AC it in Michigan?
I would suggest installing radiant subslab and suspended radiant at each upstairs floor and use a single boiler to supply both heat and hot water. This is perhaps the most efficient system for central heat/DHW, as you can achieve 95% AFUE in a gas boiler.
If you do use radiant in the slab, I would recommend 4" of rigid foam board underneath (on a well-sealed vapor barrier) and comparable slab edge insulation (which is where most of the heat loss from the floor occurs).
Solar & Super-Insulated Healthy Homes