I am in the design stages of a new house. I am thinking about 1″ of polyurethane spray and 6″ fiberglass batts in the walls. 1″spray with cellulose in the attic. Any thoughts or opinions on cost/ effectiveness? Also 3″ glass on interior walls for sound?
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First off--Welcome aboard---
Second---Fill out your profile--we don't need your shoe size and all but where you live is somewhat helpful .
Besides you'll hear from the Profile Police if you don't.
O.K. about your ?
This is way to vague to even start to forulate an answer-which may be why it has sat idle.
Break it down some--Two story house or rambler--on grade or basement, full or crawl. Where you live and the square footage?
So get back to us all and we'll see what we can put together...
Again Welcome----
Mike
" I reject your reality and substitute my own"
Adam Savage---Mythbusters
Ok,This is going to be an approximately 2000 sf ranch on a Superior foundation full basement. Location is Lowville, NY (at the east end of the famous Tug Hill Plateau).
thomas... the foam is ok... but costs
fiberglass is useless
and 6" studs give huge thermal breaks..
try a search on Mooney walls if you're interested in more..if you insist on sticking with fiberglass, i notMike Smith Rhode Island : Design / Build / Repair / Restore
Maybe a dumb question: but why not fiberglass? Are you saying the studs are acting as thermal bridges to the exterior? Or the fiberglass itself is unsatisfactory? If not fiberglass, what do you prefer?Just seems like most houses are still using the stuff.
draftguy...<<<< Are you saying the studs are acting as thermal bridges to the exterior? Or the fiberglass itself is unsatisfactory?
If not fiberglass, what do you prefer?
Just seems like most houses are still using the stuff.>>>
in reverse order: yes , most houses & most insualtion contractors use fiberglass
i prefer dens-pak cellulose
fiberglass is usatisfactory.... it is not inherently a good insulator ( Glass fibers have alsomsot no insulation value ) they rely on the air voids formed between the fibers to insulate.. but , the air moves rather freely thru the batts ... check out your furnace filter...it's teh same stuff
also.. the fibers on the exterior of the wall are usually below the dew point during the winter.. any warm moisture laden air from inside the house will come in contact with those fibers and the fibers become a perfect condensing surface... moisture droplets form , coagulate into drops and seep down the wall to the shoe..wet walls, lower insulation value
fiberglass batts actually decrease in their R-value as the temperature drops..
none of the above is true of cellulose
as for studs.. they have an aproximate r-value of 1 to the inch..
so , in a wall section , you might have an r-13 batt next to an R-4.5 stud... the stud will be a good thermal bridge
studs are always good thermal bridges.. just look at a thermograph of a heated home in a cold ambient temperature... you can get a perfect outling of every framing member in the houseMike Smith Rhode Island : Design / Build / Repair / Restore
Thanks, Mike. Always looking for some better methods. :)
draftguy,
yes studs have a low "R" value and fiberglas will let air flow thru, If you doubt me go down in your basement pull out that fiberglas air filter.
Plus fiberglas is rated in a laboratory at 70 degrees what they don't tell you is that it's "R" rating goes down as the tempurature goes down..
Frenchy, et. al:Is there a web site or published reference that graphically depicts the true R-values fiberglass or any other type of insulation at descending temps? (i.e. not sure whether this drop in R-value effectiveness is just relevant to F/G.) Jimz
Hello Thomas--the general consences is right up my line of thinking---Air infiltration is the killer--and FG is it's favorite air permimble product.I can imagine that NY the winds can blow and temps can get to zero right?I'd rank thermal bridging right up there with air and insulation.In union you can put together a mean package but ignore any one and your bills will reflect it.If I was putting up a new house here-MN. I guess I would use Sips or stud const. with a thermal break--ie foam board over sheathing then side--IMHO I just can't see the foam being sprayed consitantly enough to get an even surface to use FG---I guess I would consider the foam for air and then blown cellulose to finish off the stud cavieties.Same with the attic space--As for the rim I would go foam all the way--Who want to tuck FG in all those spaces and it is easy to ge t thru to run future lines thru. Repair with a regular foam gun or in a pinch foam in a can.I am not familiar with what a Superior foundation is--Wood? ICFs? So I am at a lose there.Hope this helps--Mike" I reject your reality and substitute my own"
Adam Savage---Mythbusters
>> I am not familiar with what a Superior foundation is << I think he meant Superior Walls - which is a precast foundation set in place by a crane. It comes with rigid foam insulation (maybe 2"?) and the panels are cast in a factory laying in the horizontal position so they can use a thin 5000PSI concrete.
Superior Walls----Somewhat like ICFs? is the foam only on one side?Something new to learn about--not that I am big into foundations but interesting nonetheless.Do they use old fashion butt joints in the corners or do they mitre them? Hardy-har-harMike" I reject your reality and substitute my own"
Adam Savage---Mythbusters
Superior walls are not much like ICF. Here is Superior Wall's home page, http://superiorwalls.com/index.php but also, look at this one http://superiorwalls.com/products_xi.php as it gives some details as to how the walls are constructed. They are poured in a factory per plan, trucked out to the site, and then assembled. And yes, the corners are mitered - seriously!
The thing that is really odd about them is that they do not use a footer. Rather, the site is excavated and then small gravel is placed - can't remember but it's maybe like 3/8" washed stone. The stone is carefully leveled and vibrated. Then the walls are set in place with a crane and bolted together with a polyurethane (?) sealant between the panels. The bottom of the wall, which I believe is 8" thick (or wide), just sits on the gravel.
One thing that is pretty cool, if I remember correctly is that they are made of 5000 PSI concrete which is inherently waterproof - as is. Still most people apply a coating or membrane to the outside of the foundation.
The actual install goes very quick maybe a day at the most. OTOH, you still have to wait while they make the panels in the factory.They charge by the linear foot and extra for corners, etc.
Thanks for the link--I'll look into it for my own information--Ya never know I may have to diversify someday---I Don't Think So---Mike" I reject your reality and substitute my own"
Adam Savage---Mythbusters
Mitremike, Northern New York winters are brutal, do you or anyone else have any experience/ thoughts on the insulated siding that certainteed has out? What are the chances that it would do the same thing? Is it enough for a thermal break? The Superior foundation is precast concrete with 2" insulation.
Ya got me on the Certainteed siding so I'll leave that one to the others. Matt gave me a link to Superior so I'll have to check it out for my own entertainment.My parents lake house is built similiar but with a wood foundation--They layed a crushed stone base--seemed larger than 3/8 but I am going off memory--IAC--they have a bed of stone and set the walls on that--2/8 studs with a 2/10 bottom plate on the stone--It seems to have held up well. I'm sure they weren't built on site so the builder must have ordered the wall and had them placed similiar to the Superior system.Hope your project goes off well--Let us know--Mike" I reject your reality and substitute my own"
Adam Savage---Mythbusters
Welcome,
It seems that here (in Lower Michigan) the most common application is 2" on the whole project but that may be due to code required R-values.
Also the first inch cost more than additional inched around here.
Good luck,
Garett
Hi,
Some of the builders around here (SW Montana) use the one inch of PU foam plus batts in 2X6 stud walls. They feel that the foam provides good air infiltration protection, and the FG saves them the cost of filling the entire cavity with foam. Seems sensible to me.
Gary
http://www.BuildItSolar.com
Momper Insulation, a large contractor that covers a large part of the state of Indiana, uses a closed cell foam spray insulation that they apply to a "veneer" thickness of 3/8" minimum. Then they fill the 2x6 wall cavities with unfaced glass fiber.
The foam gives a quite complete seal against air infiltration, and the glassfiber provides the insulation.
If you are doing a 5-star job, you ask your electrician to use those blue plastic boxes outside his work boxes, the ones with the large flange for sealing against the sheetrock. Foamseal the penetration where romex comes into the box.
Standard Insulation, a large contractor that is operation out of Utica, NY, does ceilings below roofs by first stapling glassfiber roll insulation up between the ceiling joists or truss chords. R13 thickness is used, and the staple-up is done so there is enough of a cavity between the insulation facing and the ceiling line to apply about an inch of sprayfoam. Then they go up into the attic and blow in cellulose atop everything. The foam and glass yields about R20, and the cellulose is blown at a thickness to give the rest. Figure about R4 per inch for the cellulose.
Good insulation practice is OK, but the biggest bang for the buck is working to seal against air infiltration. Use techniques such as sprayfoaming the band joist, low-rise foam seal around all windows and doors, sealant at the joint where sill plates sit atop subfloor, foamseal all penetrations where anything comes through the wall, etc., etc.
Are you thinking open cell or closed cell foam? The reason I ask is I'm wondering where your vapor barrier will be. Also what is the exterior sheathing to be?
Also, I gotta kind of wonder about putting a full 1" of foam and R-19 fiberglass in a 2x6 (I assume) wall? Won't the fiberglass end up being compressed?
Re what the previous poster said about the electrical boxes attached are some pics of a few different types. The last 3 have a rubber seal of sorts where the wire is pulled through and a gasket material on the face. Aren't we just great at helping people spend their money?? :-)
Matt, closed cell, osb sheathing, 6" wall. Would 1" compression of the insulation hurt? make a difference?
thomas61
You didn't list where you are but if heating/ cooling costs are important you might consider SIP's I know that is a new concept (I mean it's been around for well over 60 years ) but it was only begun to be used in housing in the 70's with a few timberframers.
by the 80's a few brave souls started to use it in normal homes and today it's one of the most cost effective ways of building..
If you live in the south you might consider ICF's
Let me dismiss a few myths. SIP's don't need to cost as much as a traditional stick built home and they can be built in much less time.. Currantly in this market ICF's have a 2% premium over stick built but quickly gain back the differance in lower energy bills.. I suspect the reason for the 2% premium is that there are so few contractors competeing for the market..
SIP's are a thought, but I havent seen them used locally. My fear is being the guinea pig for a local contractor. Also, how do you run wiring or any other utilities through them? As for ICF's I worry about the headaches of ever re-modeling ( moving/ altering a window or door opening).
thomas61
Wiring is a breeze but often people are unwilling to change.
You can have the factory put wire chase any place you want. Interior walls where most of the wiring/ plumbing is done are built the normal (stick built with 2x4's) way so there is no change there..
You should never put plumbing in outside walls in the cold areas of the country so plumbing comes up from the floor same as before..
I ordered all of mine withoput wire chases and simply used a spade bit with several extension to put the wiring where I wanted it.
Face it, how tough is it to drill thru foam?
ICF's, Well you obviously haven't been to a rental center lately.. they have saws that will quickly cut right thru concrete and drills that will make holes for plumbing and wiring..
(thank goodness since I forgot a couple of things when I built my basement with ICF's)
If you think things thru you'll remember most and what you forget can quickly be solved at the rental center..
Same with remodeling..
To do that, you would need to frame with 2x8 studs. You would be far better off with Mooney walls for that dimension. Or frame with 2x4 and use 3" of foam.
Or fill with cells in a 2x6 even
anything but FG batts
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Did you get a quote from Standard Insulation out of Utica?
Stinger, I havent gotten a firm quote from them but an approximate. I really haven't gotten any others yet as we probably will not begin construction until May.
I'd be worried about getting intimate contact between the undulating surface of the spray foam and the fibreglass batts. If you leave a cavity, any cavity, in your insulation, you have just set up a convection cell which takes away a good portion of your insulation's value. Not nearly as bad as if you had the same gap between your sheathing and the fibreglass batts alone (i.e. no foam), but definitely worse thermal performance than if you filled the cavities with foam or dense-packed cellulose.
If effective insulation is what you want, then you want zero air movement from outside to inside and vice versa, plus as close to zero air movement within the insulated cavities as possible. You also want to minimize the amount of wood which connects your sheetrock thermally to your exterior finish. An interior or exterior thermal break gives you enormous thermal efficiency bang for the buck.
Best of luck to you- the Icynene truck is arriving here sometime this morning. What the heck- it's only money, and you only insulate once!
this is a thought 2x4 or 2x6 walls
vapour barrier over the insulationand studs
electrical on top of vapour barrier
2"isolofoam on top of vapour barrier and cut electrical boxes same as you would for drywall
the syrofoam has notches for 1x3 strapping to fasten drywall works well
and styrofoam works well for rim joist insulation
Hey Thomas,
Welcome. For information on SIP's you can go to http://www.insulspan.com. I know there is an authorized installer in New Hampshire that comes into your area regularly. Superior wall of Hudson Valley does the precast foundations and they are probably right near you too. The SIP installer's website is http://www.panelpros.com. There is also an insulspan dealer in Summitt, NY.
The CM
Edited 1/30/2006 3:59 pm ET by the cm
I looked up summit on a map (I looked on their site for contractors and that is the closest)and it is about three hours from Lowville where I live. I would be interested in the product if there was a conttractor near me (northern new york)who installed them.
Hi,
There is an NREL calculator that does an estimate of R value for actual wall construction, complete with studs and framing thermal briding here:
http://www.ornl.gov/sci/roofs+walls/AWT/InteractiveCalculators/rvalueinfo.htm
Here are some results from running the calculator on some sample 2X6 walls that I thought were interesting:
All walls are wood framing, 2X6 studs 24OC, wood siding.
No exterior foam, R19 FG: Clear wall = R18.9; Whole Wall = R14.1
1" exterior foam, R19 FG: Clear wall = R23.4; Whole Wall = R18.4
No ext foam, PU in wall: Clear wall = R28.5; Whole Wall = R16.6
1" ext foam, PU in wall: Clear wall = R33.5; Whole Wall = R21.3
Where the "Clear Wall" R value is a wall with studs and plates, but no framing for doors, windows, and no corners.
"Whole wall" is a realistic R value for a full typical wall with door and window framing and corners.
It seems like even with the very good PU foam, the thermal bridging from the studs and framing just kill you. Ordinary FG with 1 inch exterior foam board is better than the PU foam without the 1 inch exterior foam?
It looks to me like the 1 inch exterior foam really pays its way?
Unfortunately, the calculator won't do the 1 inch of spray in foam with the rest of cavity filled with FG, and no exterior foam.
Gary
http://www.BuildItSolar.com