I have been getting prices on Sprayed in urethane foam insulation hoping to maybe switch over to that instead of the fiberglass we use now.
I can not understand how an R-value of 13 with foam is better than an R-19 with fiberglass. But each company I am talking to tells me the same thing. This would be for the walls.
And the more confusing thing is that each of the companies wants to put something different in the ceiling. One says blown in fiberglass. One says blown in cellulose. The other says spray it with foam! Why would I spend the money on foam in the walls and then just put fiberglass in the ceiling? From the independent tests I’ve seen of fiberglass and my own experience it just isn’t the best thing out there right now. I’ve heard cellulose isn’t all that much better. Any thoughts?
Another thing I can’t get over is the fact that they are saying you don’t need ventilation if you spray the foam right on the under side of the roof sheathing. But why heat that whole attic area. Anything your saving by using foam is being used to heat the attic!
I would just discount all this info if it was coming from one person but it’s three different ones so they must know what they are talking about, right?
Who has experience with spray foam? ANyone using it in their new homes?
Replies
I am sure somebody will spell the answer out to
you, but you might want to try a search on "foam".
There is a ton of threads that go very deep into
this subject.
"I can not understand how an R-value of 13 with foam is better than an R-19 with fiberglass. But each company I am talking to tells me the same thing. This would be for the walls."
The R-value is only what shows in a test for the basic product, not installed.
fiberglass bats loose their Rvalue as the tempature falls because of internal air ciculation within the bats.
The other thing is that FG batt's don't do much to block air leakage to the outside.
"Another thing I can't get over is the fact that they are saying you don't need ventilation if you spray the foam right on the under side of the roof sheathing. But why heat that whole attic area. Anything your saving by using foam is being used to heat the attic! "
Well it depends. If you have any HVAC equipment or ducts in the attic then you can gain a lot by having them in conditioned space.
And you have many, many more holes from the house into the attic than through the roof to the outside.
"The R-value is only what shows in a test for the basic product, not installed.
fiberglass bats loose their Rvalue as the tempature falls because of internal air ciculation within the bats."
Bill,
What if you can mitigate the issue of air circulation?
The reason I ask is that in my house, a 1920's cape sitting high a top a hill in SE Wisconsin... -20F with -80F wind chills the norm in Winter, has really low heating bills, and FG insulation. It has loose construction (1 x 6 sheathing and roof decking).
What I did when I rehabbed it, was place 1"foam board (R-5) in the 2x6 rafter bays and up the back side of the knee walls (with a 1" air space from the decking). Caulked it all in, effectively creating a sealed box. Added R-13 fiberglass into the 3.5" deep cavities, then prior to 5/8 drywall, laid up sheets of foil faced isocanurate (7.5R at the time I think) foam board, that also created a thermal break to the roof rafters and knee walls.
Even keeping the heat up to 73F, my bills are 1/3 of what would expect. About $120/month for a 2,400sq/ft house. That only adds up to R-25.5, in an area where code minimum is R-38. most folks with new homes that size often have bills close to $270/month.
Jon
There are two types of air movements.One through the product from inside to outside.The other within the FG.And you have done a good job of sealing off the air flow from inside to outside.And I don't think that you have near as much driving force with in the couple of vertical inches that you have in the joist cavity to get internal air circulation as you do in an 8ft stud bay.And I realy, realy wonder what the effective R value is of FG (or loose blown) FG in normal installation with the surface exposed to moving air.I would not be surprised to find that you 1" of polyiso is more effective than than a 6" (r-19) bat with the surface exposed.But I have absolutely no numbers of that to know if that is true or not.
wonder what the effective R value is of FG (or loose blown) FG in normal installation with the surface exposed to moving air
Blown-in FG will be better, by testing, as it will fill the bay. Better in practice, especially with moving air-who knows?
The real problem with FG batts is the imprecise way they fill a bay. Sure, the bays are supposed to all be 14 1/2" wide--some are, some aren't. The batts are supposed to be 14 1/2" wide, too. But a 14 1/2" wide batt isn't going to fill a 14 5/8" bay very well. And, nobody is likely to properly trim a batt to fit a 14 3/8" bay. And all this is just with the realtively "easy" and "regular" long dimension "fit."Occupational hazard of my occupation not being around (sorry Bubba)
Yes, but that is not my real question. With the "pink" (vs the white BIBS type that Piffin is talking about) no matter how installed or how well it is installed in the attic what is it's "real world" R-value with one side completely exposed to the air.
what is it's "real world" R-value with one side completely exposed to the air.
LoL! You want reality? Just about any value is derived by "testing" which can be "un"real in phenominal proportions. (Testers don't like it "real," the cool $$$$ IR scanning thermograph doesn't "like" studs cooler than walls & such . . . )
I'd be surprised that any "loose" material with an exposure to moving air would perform as well as a monolithic or homogenous one would in the same conditions. I've tacked 1/2" blue foam sheets over various kinds of loose fill ceiling insulation. Perceived performance improved--whether that was due to decreased exfiltration, or due to limiting air movement would be hard to call.Occupational hazard of my occupation not being around (sorry Bubba)
Workshop Jon,
I would love to measure your walls.. I bought a cheap infrared thermometer, (about $35.00 I think) and I've discovered all sorts of things that I never realized before..
You can actually "see" where the studs are in a wall due to much lower tempuratures.. you can also find cold spots where the insulation is less than perfect..
I love to hear that your heating bill is lower and I wonder if there might be another reason why it's lower than your neighbors.. speculation leads me in several directions.
Where can you get an IR thermometer for $35?
Jon Blakemore
Mines a Raytek mini temp I bought for the race car.. found about a million uses since..
Where can you get an IR thermometer for $35?
I think I saw something similar in the Harbor Freight circular--which might make the question "will it out last the first set of batteries?"Occupational hazard of my occupation not being around (sorry Bubba)
Mine is now about 4 years old and the original battery still works.. Actually looks to be an American product rather than a chineese import. (raytek mini temp)
I would love to measure your walls.. I bought a cheap infrared thermometer, (about $35.00 I think) and I've discovered all sorts of things that I never realized before..
You can actually "see" where the studs are in a wall due to much lower tempuratures.. you can also find cold spots where the insulation is less than perfect..
I love to hear that your heating bill is lower and I wonder if there might be another reason why it's lower than your neighbors.. speculation leads me in several directions."
Frenchy,
On "frosty" mornings it's interesting that one can't see the positions of my roof rafters as thing start to warm up vs. my neighbors which I can see. Now they all have minimum R-38, and probably closer to R-50, vs. my 22.5
Personally, I think the way people through around R values is bs, since creating thermal breaks which obviously increase R's don't count towards meeting code. By the way, my house does have newer windows and similar insulation for the walls, as well as a 92+ furnace.
Jon
Workshop Jon,
To see how effective your insulation package is you'd probably have to use an infared camara or some such measure. I doubt that your observation is particularly valid since other things could be entering the equation. For example compare the frost levels on your roof versis his. If your roof is frost or snow free while he has snow then you are obviously heating your roof deck higher than he does.
I have one neighbor with visably poor insulation brag to me that his heating bills are several hundred dollars cheaper in Jan. than mine are.; He's right, he's heating about 2800 sq. ft. versis my nearly 5000 sq.ft. In addition he has far fewer windows.
One neighbor has very heavy drapes she pulls over her windows every evening and opens every day, I'm certain that helps her to lower the heating bills. In addition My house is sited terribly with regard to the sun, while your house may benefit greatly from the sun in relation to your lot.
All of those factors directly affect a homes heating bill, not to mention the cost of energy and how well the house uses it's energy.. For example most HVAC installers put forced air ducts right under windows. while you need to do that to take the chill off air that "leaks" out of windows, it is not the most efficent way to heat a house.
Thermal mass too enters the equation.. If you heat a heavy thermal mass up it retains it's tempurature much longer and yields it up slower than the typical forced air house does.;. By taking advantage of solar gain during the day a high density mass like timbers or heavy tiles can yield the heat at night during sleep when less heat is called for and the furnace won't be forced to work as hard or often.
interesting artical it is to my understanding that the foam spray is mostly used to just seal the house from air infiltration therfore eliminating the need for housewrap i did a house that was sprayed on the interior of the sheating against the studs{2x6}then they aplied there fiberglass on top of that they said it was also adding an extra r value of 7
we use Dens-Pak cellulose...
http://forums.taunton.com/tp-breaktime/messages?msg=53289.3
Edited 1/27/2005 11:07 pm ET by Mike Smith
Convection Currents
Thats the real enemy of keeping a structure warm (or cold if its hot outside). R value dosent mean squat if there is air leakage. Imagine you are wearing the warmest coat made and you are standing on the top of Mt Washington. If you have the coat unzipped a bit, your neck and chest are gona be cold.
Same thing with a house. Every little nook and crany contributes to the perfomance of a structure. Thats why the guys here are always tellig people to seal holes and leaks first before you insulate.
That said, foam is great beacuse it expands to fill every little gap you didnt know you had.
It makes sense to insulate the attic If there is going to be HVAC or you plan on converting it to a livable space. If its just gona be dead storage then I probably woudnt bother and would just stick with the ceiling plane.
I just recently had my house sprayed. Search in Picture Gallery, posted by me, subject "Foam".
At any rate, the comparison between foam and fg on R-value is just plain silly. R-value is some stupid measurement that was invented to compare thicknesses of fg. It only represents one aspect of how your house losses heat (and it does that poorly). Spray foam totally eliminates air infiltration, which is not measured by R value. If you want I can post pictures of the foam squezzing out sheathing cracks, electrical box penetrations, my fake ridge vent, etc.
I've never lived in a house this warm. In fact, we keep the heat 2 degrees lower now because the house isn't as drafty. The heat doesn't cycle much.
I also sprayed my roof deck with no ventilation. Had to go to the mat with building department, but in the end I won. I did have a building science engineer look at the installation unvented and convince me it would be ok. Basically we used an open cell foam so the roof could "dry to the inside" if it's get wet. I have asphault shingles, which he claims will wet the roof sheathing if the shingles get blasted with sunshine after getting wet. I don't know where you are (I'm in central NC), you should read buildingscience.com - they have "acceptable" roof assemblies for certain parts of the country. Almost all parts of the country can support unvented roofs.
I never worried too much about heating and cooling that extra space. I never ran any numbers, but it seems to me that it would pretty much just go along with the interior temperature without a whole lot of extra BTU. Maybe I am totally wrong on that. But you are only increasing your surface area of your thermal envelope by a little bit.
MERC
We've been doing a old farmhouse rehab and we just insulated with foam. All I can say is WOW. The place was completely gutted and we filled the exterior shell with 3" of foam and the underside of the roof with 5".
It was sweet on a couple of different levels. I've always hated working with fiberglass. Second no matter how well you work with fiberglass you get air infiltration. Foam handles both problems.
The place is tight. 1700 sq feet is being kept at 50 deg., give or take, with 700 square foot of radiant floor(one zone). That may change as we put up the sheet rock but the outside temp hasn't been above 10 for about a week.(upstate ny) I'm impressed.
The foam guy was in at 9 out at 2 clean neat no headache kind of deal.
so.. TMO.. i see you're in upstate NY..... what did you pay ?
did you get other prices ?
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 1/28/2005 12:22 pm ET by Mike Smith
Did I mention the foam guy came back the next day to check for cracks?
We had three estimates the high was $8000 the low was $6700 and the winner originally estimated 6900 but sent an invoice for $6400. HO asked him to leave a section cieling to use up some old fiberglass he had in his barn. Roughly 3200 square feet insulating 18 square roof 14 square walls.
Hey Merc,
Would you mind elaborating on your pitch to the building department regarding no ventilation in your foam insulated house? I have insulated with spray foam and I'm thrilled with it but I've also heard arguments that it can make a house "too tight", that you need an HRV (heat recovery ventilator).thanks,
You can do ventilation for cheap with a bathroom fan, on a 24-hour timer or just left on all the time. Use Panasonic or Fantech and you won't know it's on. You only need it in spring and fall, other seasons windows are open or the boiler/AC is bringing in fresh air. You should do some detective work to see where intake air is likely to come in though. In my old house, it comes in through the gaps in the sheathing and the 75-year-old tar paper, sigh....
My roof is all cut up with cross gables so it was effectively impossible to meet venting code. I called my BI, explained that it was physically impossible to meet venting code and then said I was going to spray foam, unvented. He says "I don't see anything in the code that allows me to approve and unvented roof". Then says to just drill my valley jacks and do the best I can (and then call a structural engineer to approve the butchering). I sure wasn't butchering up my valley jacks with some holes to satisfy some undereducated building inspector. That technique is only marginal anyway.
So I contacted a building science engineer. He flies all over the country doing work so he is well known. He happens to live in this area. Had I contacted him before the roof was built, life would have been easier. The main problem we had to deal with was that I had asphault shingles with tar paper on the roof. Apparently when asphault gets wet and then heats up rapidly, it drives moisture into the roof. So if you don't vent, you either need to use a water impermeable membrane on the roof (like metal roofing or special tar paper type stuff) or you need foam on the inside which can let moisture through it (open cell). So we went with an open cell foam. I had the engineer write a letter and he attached some various weather maps and information on dew points, blah, blah, in addition to a copy of the newly accepted NC code that allows for unvented roofs. My building inspector had a few other follow up questions, I gave him the information and set a date for spraying the foam. Told him I was spraying on Dec 4 unless I heard from him. I never heard the job is done and signed off.
As it turns out, the guy that sprayed the foam claims the foam he sprays will appear in code by name (Demilic). I'm not sure code would ever do that, so whatever I guess? Just something he said to me. He also had a letter from a few roofing manufacturers that warranted their shingles over the Demilic foam. I used that letter to satisfy my BI on roof shingle warranty, though I still don't understand why the BI cared about my warranty. But he did so I appeased his fears.
While it's true that spray foam can make a house too tight, you need to test to find out. I actually have a big furnace in my not-so-tight basement, so it draws plenty of air through cracks down there. Air must be finding it's way out somewhere because air is coming in. You really need 0.35 air changes per hour to be considered "healthy". YOu need to blower door test to figure it out, and a blower door will also allow you to set your HRV or ERV correctly (to provide the exact ACH you need). I haven't done this step yet, but I will when I'm all done spraying foam.
BTW, the birds love this stuff. I have some foam I sprayed outside and haven't covered yet. I have two birds that I run off about 5x/day. They don't do much damage but it sure sounds like it.
MERC.
An air exchanger is required in the northern portion of the country due to how tight you can get a house with foam.. Stale air is a real problem and needs to be addressed.. somebody else said thatin his climate using a bathroom fan vented to the outside is a simple solution but it's effectively pumping heat outdors..
using that same bathroom fan if you pump it into a heat recovery unit (air exchanger) you'll recover about 80% of the heat while getting plenty of clean fresh air.. Since we are only talking about a 3 inch hole typically recoving 80% percent of the heat will make a significant reduction in your heating bill...
That was my understanding ventilation as well. Do you know of any reputable makers of HRV's? "LifeBreath" is the only one I've checked into.
http://www.broan.com and http://www.fantech.com, both good sources for HRV's
chicwhtools,
I've looked at several brands over the years but have never found any fair or unbiased grading or testing of air exchangers, seems to be a shame too since the houses are being more and more closed up..
I do see the potential for serious problems too, Do you remember the legionaires disease scare of a decade or so ago? The problem was eventually traced to improperly maintained air conditioners and the matter seemed to drop from sight.; the problem is if you consider what it took to grow that bacteria we have a similar potential problem in an air handler...
While mold can be an issue for some if they are particularly sensitive or the mold content is extremely high, as a long term issue I can see where an air handler/exchanger could prove worse!
Once I find a top rated brand I intend to use a Ion air filter on the outlet side of the air handler, the required maintinance on that should cause me to periodically open the air exchanger and service that as well. (at least that's my intention)
Let me give you actual numbers.. so you can see the real differance between fiberglas and foam.. I'm currantly building a timberframe house.. It uses foam panels (SIP's ) and they are 6 inches thick on the walls and 10 inches thick on the ceilings..
The part of the house that is still done in fiberglas is very drafty and we watch TV with blankets on! the tempurature is set at 72 degrees and the overall temp in the house is about 8 degrees lower than that.. (digitle thermometer) If I sample the foamwalls they are 66 degrees while the stud walls vary between 53 and 49 (49 is where a stud is and 53 is where the insulation is...)
Outside air temp was 10 below.same building same heat source measured at countless locations.. The ceiling at 28 feet is exactly the same tempurature in the great room 28 feet above the floor with 10 inch foam panels on the ceiling.
The portion of the house that is fiberglas insulation has a 14 degree differance between the floor and a 8 foot ceiling..
This house was perfectly well insulated. In tearing it apart if find noplace where there wasn't a good vapor barrier or where there were any signs of air leakage.Fiberglas was stuffed in every single corner and crevis.
I think the final point I should make is that slightly more than half of the house has only one 4 inch heat duct to it.. that's the half with the foam panels.. the other part of the house done in fiberglas and celuliose has 14 4 inch heat ducts..
!4 times the number of heat ducts and it's colder!
14 times the number of heat ducts and it's colder, much colder!
Ok all I hear are good things about foam. But should I go with cellulose in the ceiling or just bite the bullet and put in foam in the ceiling too?
I also have a hard time going from over 12" of insulation in the ceiling to about 4"!! But I understand about the air infiltration.
FOAM EVERYTHING. FORGET ANYTHING ELSE. IT'S JUNK.
MERC.
What kind of shingles do you have?
To elaborate the foam guys had letters from certainteed stating something to the effect that the warranty wouldn't be void if the underside of the deck was foam sprayed.
Foam the ceiling but check to see what it would cost to do 10 inches or so.. Well, actually you may not need the ten inches, it depends on where you are and how much heating/cooling you do.
I got ten inches and while I can't see where another 2 would have done much good, I still want more!
If I can save three btu's from escaping then I have three less BTU's I need to buy , at the cost of BTU's insulation is a great bargan ..
I like the fact that insulation is a one time purchase and that once done the cost is fixed and will never rise.. will the cost of heating rise? as sure as the sun comes up in the East..
You can safely expect the cost of energy to more than double in the next decade.
My annual heating/ cooling bill on a well insulated house was just a little over of $2500.00 a year I honestly expect the total to be around $900.00 when finished.. thus in a decade I'll save $16,000
even if I'm way too optimistic I'll save at least $12,000 per decade and that savings will continue as long as I live in this house.. (hopefully untill I'm worm food)
ejc.... our normal attic gets 20" installed ( settled density ) so we blow about 24"..
that's flat attics, about R-60... if we're working a cathedral ceiling and there's access we'll blow that at 24" too..
if the acess is only the thickness of the rafters... we'll blow it DensPakMike Smith Rhode Island : Design / Build / Repair / Restore
If you are still consideering using another kind of insulation in the attic, you still don't understand foam and infiltration. Cold air sneaks in at the bottom and hot air leaks out at the top. To prevent the infiltration, you need to seal against BOTH.
That means the installer goes into the crawls space and sprays the sills and band joists
and then he does the attic or cieling
and then he does the wallsI can't understand why a foam instaler might recommend using other products on the cieling. Sounds like he does not thoroughly understand the product, or is trying to overcome sticker shock instead iof selling on it's merits and dumbing the price down while compromising the integrity of the system.If you wanted to compromise to gain agaionst the high cost, spray two inches on the cieling and then send in as much cellulose as makes you feel happyfrenchy has good testimonial evidence,a s do others. I have never had a customer unhappy with a foamed in place insulation job. Most are extremely impressed, and one advantage that has not been mentioned here yet is that it makes for a much quiter house.But don't go as far overboard as Frenchy. Corbond studies show that instaling more than four inches in a cieling drasticaly reduces your rate of return. That rate of return does depend on energy cost future vs. installation cost present and on your climate re the temperature differential between in/out temps. or on the degree days in your areas heating or cooling season
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Lets not forget that Corabond is a closed cell foam and abought twice the R value per inch that icynene is. But yes the bang for your buck quickly drops at a certin point with either type.
I'm not sure where the icy crept into the thread. The original Q here was about the urethyene foams, so that is my context.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Icy is not a urethyene eh? I thought the main dif between the two was the blowing agent creating either open cells or closed.
Though they won't say for sure, I think Icynene is a polyisocyanurate rather than a true polyurethane. So it's not just a difference in blowing agent, it's a difference in polymer chemistry.
"Though they won't say for sure, I think Icynene is a polyisocyanurate rather than a true polyurethane..."Polyiso boards are R-7 and icynene is R-3.x.....?
There dozens of different kinds of foams, with only five or so being common in house insulation. They have different chemical names because they are different from one another.Then there are differing Brand names, like Corbond, which is a urethyne foam with borate additives and a colourant to identify it on sight. They have a patented, I think, system based on the aditives and the installation procedure which is based on extensive research
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffin, is it your experience that the extra cost of corbond (or any poly) is worth the added cost over the Icynene (or any open cell foam)? 'Round here, Poly's seem to be used mostly in basement applications.
_____________________________HomeBase__________________________ LLC
Edited 1/30/2005 8:38 am ET by homebaseboston
I don't have icynene available up here so can't compare costs but I am sold on the urethene sprays.I also use a lot of radiant surfaced ( Thermax or other brands) polyisoanurate foam panels in walls and cielings to break thermal bridging.I am slightly turned off by the icy spray idea, for two reasons. one is the open cells nature allowing permeability and the lower Rvalue.The other is that I keep hearing that icy instalers are making same claims that Corbond does about certain advantages of foam, but failing to back them up with evidence. Seems like they are riding the coat-tails of the research and good reputation of urethyene sprayed in place foam systems with a lower value product. I wish I knew what pricing it went for.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Piffin,
You make a good case for not going overboard about foam, however here in Minnesota you simply cannot go overboard, When it costs hundreds of dollars to heat in the coldest months of the year You'll wish you had doubled the level of insulation.. (as for those darn windows,...... )
But I believe that even in moderate climates like San Diego there will be an eventual payback,, the cost of heat/cooling will go up with the cost of energy.. while the price you paid for insulation will remain the same..
At what point will you achieve payback? well, that as you say, is a matter of degree days and cost of energy.. If it takes 10 years for a payback would it still be worthwhile? I think so, in that you should still enjoy several more decades of reduced energy bills.
If we add the complexity of a higher mortgage payment into the mix and do some guessing as to potential lost income opportunity there is a chance that the payback issue could become muddled. Against that there is the green factor.
Simply the less energy we use now will mean that the environment will remain "greener" a bit longer..
One house? pretty nominal but there are 2 million new homes going to be built this year alone, (not to mention major remodels and such.) I don't know how much of the nations energy bill is involved in heating and cooling but the more we reduce it the better our balance of trade will be and the cleaner the air will remain..
An economical strategy is 1" of foam in the attic (enough for the dew point) and then lots and lots of cellulose on top.
That's pretty interesting.
I tore the roof off my house and put on a second story. Second floor and half of first floor is foamed, but not drywalled. My roof deck is sprayed so my 2nd story is significant volume as far as heating/cooling is concerned. I have no HVAC upstairs and it stays at about 65 degrees no matter what it is outside (floor to ridge). Obviously I'm getting heat going up the stairwell and through conduction through the subfloor. But for not having any heat up there at all, that's pretty good.
Another interesting note, I had put in a 4" plumbing stack before the spray foam, but it's not yet connected inside the house. I had forgotten to plug the bottom of the pipe. I was up on the roof the other day and the hot, moist air was just flying out of the pipe. I went inside and put a plug on that pipe real quick! That foam really plugs up all the holes in the roof deck so the air had nowhere to go. That pipe was probably the only place in the top of my house the air had to go and it was really moving through there.
MERC.
I think some good information available on this subject is located at buildingscience.com . As complicated as some of Joe Lstiburek building techniques are, he offers alot of good common sense ideas as well. In a pamphlet that he wrote called..Healthy and Affordable Housing: Practical Recommendations for Building, Renovating and Maintaining Housing...he writes.."Roofs, they should be designed to dry. That means roofs should be ventilated. It is possible to design and construct unvented roofs, but this should be done only with professional design and analysis".
As far as the foam vs. fiberglass issue I've tossed this one around enough myself for the planning of my own new home this spring. As good as foam sounds, it still is a tough choice. One thing that helped me decide was after talking to several foam contractors, I talked to one that sprays open cell foam and he told me that in some of his homes he has done he sprays 3 to 4 inches of foam in the ceiling and then goes back up the attic and blows in a bunch of conventional insulation. Just to get a higher R-value, that tells me that there is more to R-value than alot of them lead you to believe.
how does foam vs. fiberglass insullation compare in the aspect of wear and tear? if either were to get wet, how would they stand up? i know the fiberglass is pretty much useless after it gets wet - how does the foam go?
also, how does the foam work against other factors? like aqe? or how about critters trying to make a home in it? i know with fiberglass, certain "critters" eat it up! and destroy it.
how difficult is it to work with the foam for later projects?
also, lol - what color is the foam? i kinda like that sexy yellow or pink fiberglass!!! lol
I selected a foam that had Borate in it for just that reason, critters eat it and die,, serves them right... chipmunks and squirrils used to steal the fiberglas and celluliose to make their nests with ..
Borate's an insect repellent, but will it really work on squirrels? From what I know of the little b*stards, I doubt it'd deter them much and it certainly won't kill 'em. LD50 for rats is about 5g of boric acid per kg of rat body mass- that's a lot of foam, even if it's loaded to 1wt% with borate.
There is nothing in foam that a rat would want to eat, No nutritional value! Plastic tastes just as bad to them as us. Now they will knaw at it to get to some real food but they'd do the same to any form of insulation, if you have rodent problems no one insulation is better than another.. deal with the pests first!
Steve,
please reread what I wrote regarding the tempurature of walls.. just for you, I'll give you the numbers.
Fiberglas walls 49 to 53 degrees VS foam 66 degrees. minus 10 degree day with the house set at 72.
If I measure the floor and the ceiling of my great room the tempurature is within 1/2 of a degree. the ceiling is 28 feet away.. (foam)
The part of my house that has celluliose in the attic a 8 foot ceiling is 11 degrees warmer than the floor.. measure the temp on the roof and it's well above freezing (34 degrees ) while the roof of the foam is 10 degrees below!
"One thing that helped me decide was after talking to several foam contractors, I talked to one that sprays open cell foam and he told me that in some of his homes he has done he sprays 3 to 4 inches of foam in the ceiling and then goes back up the attic and blows in a bunch of conventional insulation. Just to get a higher R-value, that tells me that there is more to R-value than alot of them lead you to believe."" that tells me that there is more to R-value than alot of them lead you to believe."Who is THEM?And what is the "more to R-value"?My guess is that the local codes require a certain R-value as figured by the multiplying the listed r-values by the thickness and adding iin the r-values of other parts of the assemblies.And those product r-values are based on test of heat transfer between two plates. None of this gets into the amount of heat loss through an actual assembly, specially when part of that is loose fill with air cirulating around it.If the specs where on actual BTU losses per sq ft of ceiling and there where test showing "in use" losses for different materials I suspect that you would see much less of foam combined with blown.
them would be spray foam contractors,and "more to R-value" thing would be the sales pitch you get when you talk to them and they say things like air infultration (or lack of)and sealing the building envelope being just as or more important then the actual rated r-value
Frenchy: I was just correcting a misconception about what borate is and what it's for. It's primarily for bugs, not for squirrels and other rodents.
Doesn't matter if it tastes great or is less filling- nutritional value or no, if you've got something chewable in your place and a squirrel comes into it, that chewable thing will be chewed. The little b*stards got into my garage and before I caught them they'd torn all the polyurethane foam out of the passenger side seat of the old convertible I had stored in there, so they seem to like foam OK. They'd also destroyed some ceramic fibre insulation I had set aside to use on my bronze melting furnace (hence the handle here on the forum- a wierd thing I do as a hobby...) Can't imagine that tasted too good either, nor was it too good for 'em (but the trap I set was worse by far...) So taste has nothing to do with it- they want something warm to make a nest out of, and if there's foam there, that's what they'll use.
We agree that the only way to deal with squirrel damage is to keep them out in the first place! But in my case, the little b*stards found a hole which I myself couldn't find. Maybe I'll find it when I demo this old garage...Rats with PR, that's all squirrels are in my books!
I didn't read all 50 posts, but you may want to consider densepack cellulose as well, which has an excellent cost/benefit ratio. If you can seal the attic plane really well, and lay down 24" or more of cells in the attic space, you are not going to get much if any additional benefit from foam. Some folks are going with a hybrid approach- a thin spray of foam for air sealing, then cellulose on top. Foam is priced by volume.
A well detailed wall with densepack will perform very well with a great cost/benefit ratio. Nothing wrong with foams, other than cost.
Blown fiberglass is perhaps the worst insulation product. Foam vs. cellulose is the right question. Further outside the box, there is the 'foam board under drywall' + cellulose method, but you've got enough feedback to read already...
My objection to cellulose (or should I say shredded newspaper that's been treated?) is not that it doesn't perform well as a insulation material (nor will I try to spread any stupid myth about fire) but that it's insulation value goes down dramatically as it gets damp..
We all know that attics need to breathe, if they can't the shingles don't last very long and there can be other problems as well. The same vents that allow air to enter the attic also allow moisture to enter the attic.. Not in the form of rain etc. but just moisture in the air.. (80% humidity means that the air has 80% of the water it's able to carry....) It's fairly normal for things to get pretty damp just prior to the onset of winter and that dampness enters the attic thru the vent system and the insulation gets damp.. The colder it is the longer it takes for that dampness to leave. The damper the insulation is the lower it's R value is. Foam on the other hand is unaffected by moisture.
Depending on where you live that may or may not be a factor.. For instance here in Minnesota with our over 10,000 lakes things are pretty damp and moist as winter hits, However in New Mexico or west Texas that may not be the case...
One thing that helps out cellulose is that as the temps get colder the air is less and less likely to carry a lot of moisture. In Minnesota where we get a lot of freeze/thaw weather, that is not the case however in certain climates where it either gets below freezing and stays that temperature or there is a lot of dry air around Cellulose may be an acceptable trade off..
You will never enjoy the other benefits that foam offers however, Foam dramatically stiffen a building and foam also forms a vapor barrier that simply cannot be met by any other method..
"We all know that attics need to breathe, if they can't the shingles don't last very long and there can be other problems as well."
There is plenty of evidence that this is conventional myth. Venting can cause more problems than it solves.
"The same vents that allow air to enter the attic also allow moisture to enter the attic.. Not in the form of rain etc. but just moisture in the air.. (80% humidity means that the air has 80% of the water it's able to carry....) It's fairly normal for things to get pretty damp just prior to the onset of winter and that dampness enters the attic thru the vent system and the insulation gets damp.. The colder it is the longer it takes for that dampness to leave."
A good argument against venting, but during the heating season, the exterior air is usually dryer than the interior air. At the onset of winter, any moisture in the attic probably came from within the structure, as all of the building materials dry. If the structure is properly air sealed at the attic plane, the attic should stay dry. Cellulose will absorb some atmospheric moisture, but also release it. In the winter months, it should be quite dry. Open cell foam will absorb atmospheric moisture too. Atmosheric moisture is really only a problem if it condenses, which happens when warm moist air hits cold surfaces.
csnow,
I've given you the option to deal with local issues, it's pretty hard to sit in one location and say that this system is best for everyone. This country is far too diverse for that.
Perhaps in your location your method is cost effective, it wasn't here in my location.
I can say that I love low cost, and thus cost effective really appeals to me it would allow me to spend my money on things more visible..
However when I looked at the cellulose in my attic and found it frozen stiff I quickly realized that it couldn't have been very effective.;.;
Since there was no evidence of leaks though the roof and there was a complete vapor barrier installed with no single source leaks, I needed to seek other sources of what caused the insulation to become damp enough to freeze almost solid.
Keeping track of the insulation I noted that during the summer it dried out completely. When I examined the insulation in late September it was perfect. By October I noticed a little dampness and as the rain turned to snow, and then thawed again things got worse.;. by January it was once again frozen to the point of being nearly worthless.
Your allegation that foam will allow water to penetrate really goes against common sense.;. If it did they would never make coffee cups out of it.; you can fill a coffee cup with water and even though it's less than a 1/4 of an inch thick the outside never gets damp.. If water were able to penetrate eventually water would seep out...
frenchy, distinguish between water and vapor. In a closed environ, such as a building, a significant moisture differential between the inside and outside can drive vapor through many materials, including even closed-cell foam. It's more likely to happen in winter, when a high interior moisture level contrasts with a cold, low humidity outside. I don't know of any definitive studies on this, unfortunately, but have empirical evidence from some builders who've observed, and had to repair, the results. They've described examples where they could actually wring the water out of closed cell foam.On the other hand, I know a guy who's kept a chunk of foam in a jar of water for 20 years, and none has been absorbed. I think it's a bit of a trick, though. With no pressure differential between one side of the foam and the other, there's no condition that'll cause the cells to outgas and fill in with higher humidity air.My way of addressing it is to make sure the hvac system is adequate for keeping interior moisture under control in a tight building. No differential reduces the conditions for vapor drive.At least that's one of the current theories...wish it was a proven theory, be/c it can really affect the stuff I work with.
"I don't know of any definitive studies on this, unfortunately, but have empirical evidence from some builders who've observed, and had to repair, the results. They've described examples where they could actually wring the water out of closed cell foam."I would like to see anyone "wring" rigid closed cell foam!! It's called rigid because it is! If you have ever seen it you can tell. It's also used for roofing because you can walk on it. Stu
I have 30,000 bd ft of it in my house, so I guess I've seen a bit of it. Every house I design has at least 12,000 bd ft of it. I've helped spray it, I've cut it, I've sanded it, and I've finished it. The two builders I mentioned are the best foam sprayers I've ever seen, and they are restoration experts. And they're close friends. So when they tell me what they told me, and when they show me pictures, I guess I'm gonna believe them.
"Your allegation that foam will allow water to penetrate really goes against common sense.;. If it did they would never make coffee cups out of it.; you can fill a coffee cup with water and even though it's less than a 1/4 of an inch thick the outside never gets damp.. If water were able to penetrate eventually water would seep out..."
Some of the spray foam products are open cell. These are somewhat permeable. This is sometimes even marketed as an advantage, though their logic fails the sniff test.
Even closed cell foam is only 95% closed cell, and ages to maybe 85% as cell walls fail.
Jim, I'm curious about the cell wall failure thing. The only cause I know of for this is UV light. since most of what we install is immediately covered, I asee little reason to worry about losing the native abilities of the poly foam materials.However, installation is an important factor. If the mix is not right, or the temps of the substrate it is sprayed onto is too low, the quality as applied would indeed be compromised.Do you have links to objective studies re the loss of value over time from simple aging?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I'll look. I got that range of numbers from a foam mfg site. My understanding is that cells never form exactly perfectly...there's always some microscopic variation. Over the course of a day and a year they are subject to temp and humidity variations. This causes some amt of expansion and contraction...however slight it might seem, the gas in the cell (_something's in there, be/c it's not a vacuum) gets hotter and colder and therefore expands and contracts. Weaker cell walls can break, allowing the gas to dissipate and be replaced by ambient air, which likely has some moisture content. Foam made in a factory setting would likely be better quality than spray-in-place.This is how I've been told by a few different people.Edit: Here's one article: http://sprayfoam.org/CMS/index.php?option=com_docman&Itemid=31&task=docclick&bid=3&limitstart=5&limit=5One thing to note in it is that aged closed-cell foam has an R-value of 6.2 vs the 7.14/in we're used to seeing. The explanation I've seen is that cells degrade (open), resulting in lower value...still looking for that source.The SPFA (Spray Polyurethane Foam Association) in general has enough documents to fill your weekend. http://sprayfoam.org/CMS/index.php?option=com_docman&Itemid=31&task=view_category&catid=14&order=dmname&ascdesc=ASCHere's another site that lists ASTM tests for open cell content and thermal and humid aging, which implies that there IS humid aging of foam. http://www.polyurethane.org/standards/rigidtest.aspAnd http://www.rci-mercury.com/files/bz020411.pdf on the second page talks about R-value "drift", and offers a number of reasons in addition to cell wall failure, but without going into detail.Hope that's enough for starters...it all seems consistent and generally accepted within the polyurethane foam industry from what I've been able to see.
Edited 2/12/2005 1:03 pm ET by Cloud Hidden
Also note that I number of foams have an initial and aged R-value.I suspect that this is the caused by the cell walls breaking down.
Thanks. All that brings another question to my mind. Since all insulation ages and looses some Rvalue, I wonder which looses more
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The one poorly instaled.
Good answer,
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Note that some of the references indicate that it stabilizes in perhaps two years or so...reaches a plateau.
Frenchy-
Your insulation is freezing in the winter from the condensed water vapor collecting there and subsequently freezing.
The warm air inside your living space leaks up into the attic insulation through say a recessed light. This air was at 70F and 50% humidity. This might have a 50F dew point for arguments sake. Now your well ventilated attic air is 30F because you have a thick stack of loose fiber insulation up there. So, the top side is at 30F and the bottom is at 70F. The air leaks up through it and when it reaches the middle, at 50F (remember the dew point), the water vapor condenses. This happens to be in a bad spot- right in the middle of the thick fiber insulation. The only thing worst than this is a bunch of vapor barrier keeping it from drying out. That is when mold grows!
This reason is why Poly Spray Foam (PSF) is so superior to fiber. Because it blocks the air infiltration and also does not hold water at all.
Stu
Stu,
I'm sorry but you are simply wrong. There has been no source of vapor leakage in the entire portion of the house that I've torn down. (now about 70% of the roof) I carefully looked for such a leak source to explain the problem because I would like to use the cheaper cellulose if possible ( I love cheap!) . No place in the ceiling of the 2nd story are there any can lights and the wires and vent pipes that are there were carefully wrapped and taped to eliminate air leakage.The vapor barrier was about a 9mil. poly film carefully placed and taped.;
Don't feel bad, countless others have forwarded that theory about the ice.;
It seems like there are two sources to be believed about dampness in the attic. first that it escapes from leakage below and second from leakage above..
Both were wrong..
at no time during the summer in spite of record rainfalls and such did I ever find a damp spot in the attic.;
And the second has been proven to my full satisfaction thus far.
Do this experiment, take a bunch of cellulose insulation and carefully reweigh it. then put it in a spot open to outside air (but covered from rainfall) and let is sit through the rainy season and after a few days when the fog covers everything, reweigh.; notice the increase in weight? In the cool damp attic if the dampness returns again before the cellulose dries the problem will compound and continue to get worse..
You are absolutely correct regarding the benefits of foam, which is exactly the reason I went to foam insulation (SIP's)
I was careful to use a vapor barrier under the SIP's even though water cannot penetrate the foam itself.; the problem is that the edge of every panel is a potential leak source and thus even if the roof sheds all water, vapor as you point out could escape and cause problems.
csnow
you are very correct on everything except one point. once wet/damp cellulose will dry out if and only if the cellulose is above freezing.; frozen cellulose won't yeild it's moisture..
Regarding the absorbtion of water and foam could you please give me an example where a coffee cup absorbs the coffee it contains? I mean I see stains but those are all on the surface. Slice the cup with a sharp knife and the stain doesn't go more than one cell deep.
Actually found a relevant source of information, and a pretty reputable one at that...Dow! btw, the reason we speak of vapor drive rather than the coffee cup example you give, is be/c water vapor molecules are much much smaller that drops of water (if I worded that right...been a long week), and are much more readily transferred through the cell walls of the foam.http://www.dow.com/styrofoam/na/dowpipe/tech/q15.htm"Q: Doesn't polyurethane foam or Trymer* Insulation suck up water like a sponge?A: No. Trymer Insulation is a closed-cell product and does not readily absorb moisture. If, however, a vapor drive exists and the foam is unprotected, moisture penetration and wetting of the foam can occur. This is why vapor retarders are of critical importance in cold temperature service where a significant vapor drive exists.The closed-cell, non-absorbing nature of Trymer Insulation is demonstrated in the Coast Guard Flotation test where a piece of foam is placed in water for 30 days and its buoyancy measured.Trymer Insulation easily passes this test by exhibiting less than a 5% loss in buoyancy over the 30 days of this test. This meets the Coast Guard Flotation Specification, which requires the foam to lose no more than 5% of its buoyancy after immersion in gasoline, oil or soapy water for 30 days.Unlike the good water resistance of Trymer Insulation, polyurethane foam has very poor water resistance. The worst performing insulation products for water absorption are the open-cell or fibrous insulation materials like glass fiber, melamine and polyimide. These products offer no resistance to water or water vapor penetration. Unlike Trymer insulation, these insulation materials should not be used in any applications where the pipe or vessel temperature is below ambient."
CH-
Dow's statement that "polyurethane foam has very poor water resistance" must be clarified. There are many different types of foams. The main difference is density of the material. Icynene, for example, is 0.5 lbs/ft^3. That is open cell and will hold (relatively) the most water. Others make .5 lb foam too with the same result of course. The perm rating is 16 at 3" thick. No water absorbtion data given.Corbond product is 1.8 lb density and has 93% closed cell content. The perm rating is 0.8 @ 2.5 inches thick. The threshold for "vapor barrier" is 1.0 so the Corbond by itself is considered an effective VB. The water absorbtion in 0.02 g/cc.In conclusion, anyone can see from the data that the .5 lb foam performs differently than the (approx) 2 lb product. Bottom line is the 2 lb foam in no way has "poor" water resistance. The generalization stated by CH does no justice considering the huge variety of products out there.http://www.icynene.com/assets/documents/Icynene%20Spray%20Formula.pdf
http://www.corbond.com/Product/technical.asp?file=properties
Edited 2/12/2005 12:04 pm ET by Stu
>Your statement that "polyurethane foam has very poor water resistance" must be clarified.Dow's statement, not mine. Clarify them. I'd appreciate you editing your post to reflect that.
Edited 2/12/2005 10:36 am ET by Cloud Hidden
Note, PERM rating has nothing to do with bulk (liquid) water resistance.It has to do with the transport of gasseous water vapor.Lots of products have much different characteristics from one to the other.
"Blown fiberglass is perhaps the worst insulation product."Maybe you want to give a reason of some kind for your opinion before I chew it up and spit it out?FG bnatts are definitely amoung the worst. but BIBs is a whole different animal. Are you confusing the two?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
"Maybe you want to give a reason of some kind for your opinion before I chew it up and spit it out?"
Most of my experience with blown FG is removing it. It seems to leave a lot of voids within the cavities, thought that could be a result of install method.
From my perspective, blown FG is not dense enough to control air circulation through or within a cavity. Thus it has none of the 'ease of use' benefits of batts, and lacks the performance benefits of cellulose. Plus it makes for a lot of dust with sharp ends. It was delisted as a carcinogen, but it is still quite an irritant. Not seeing any advantages to this product. Am I missing something? Chew and spit away- I always try to keep my mind open to new ideas.
As with most of the negative things I have reported about cellulose, from installations done in the late seventies or early eighties, it looks like you are basing your opinion on an earlier version of the product and poor installations. The chopped FG we are blowing in now is like cotton. I can rub it on my face and not have any irritation or sharp edges. This fluffed texture is probably responsible for the better performance today also, along with studies that have led to better installation techniques. I have remioved more than my share of cellulose in the demo portions of remo work here and I would rather handle the FG than the cellulose any day, ten tinmes over, for dirty, dusty, and nasty, but that has nothing to do with performance.
For performance, the tested R-value of FG BIBs vs Cells is with ine a couple percent - and that when dry, better when damp- and the cost is within pennies too.I believe it is pretty close to a wash between the two, and wouldn't want to get in a shooting match over either side, for me, the FG bIBs is the better choice for my jobs and climate. I have no serious problems with advocates of cells either, but I just feel strongly about correcting bad information in either direction.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Do you use the same material used for the BIBS "in the wall, behind the net" as loose blown in the attic?Will settel and pack and airseal like cels?
Edited 2/4/2005 2:34 pm ET by Bill Hartmann
Ok get a load of this BS. I asked the salesman from the company that quoted blown in fiberglass in the ceiling and foam in the walls, why they figured it that way.
He said because fiberglass was just as good. You just want foam in your walls because that is where all the wind is coming from! There's no wind hitting the cieling.
If there was ever one thought in my mind about hiring this company it went straight out the window. I had a hard time not laughing as he told me that.
By the way this company is owned by another builder who is trying to keep that fact a secret. But I know and I'm letting everyone else know too. I'm going to start another thread and see if anyone would ever hire a competitor in a circumstance such as this.
Same material. Containing it in the walls behind mesh lets the installers get it tight so no settling happens. cielings are a different story, just like Mike reports with cells. it fluffs up deeper and settles in later, but pouinds is what you get and that is what you end up with. My installer expalined two ways. He said that loose blown attic - it would take like 10.5 or 11" of tight BIBs to roughly equal what you get with about 13" deep loose. Reason we discussed this is that some of my attics are also storage so i provide a plywood walkway down center sections. Where it was a 2x8 joist, we added a2x4 shim to make an approximate 11" space to blow it tight. In another ceiling we had a flat roof above to contend with, and I had him blow that tight - all 15" and then added a VB below.That whole house was about three thousand feet, IIRC, and we were heating it comfortably with just a single 220V jobsite heater up until almost christmass while the plumber worked out some bugs in completing his heating system
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Page 128 of the Feb issue of JLC is a picture/mini-article of an attic with plywood on top of 2 X 4's on top of 2 X 8 ceiling joists, to make 11 inch deep bays for insulation..
Great minds thinking alike, I guess.
I just noticed that over my morning coffee and thought of this conversation here.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!