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Spray Foam Insulation or Regular Batt Insulation???

Post in 'The Green Room' started by mdaniel, Jan 8, 2010.

  1. mdaniel

    mdaniel Member

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    I am pondering building a new home this year and have the most basic of questions to ask regarding insulation. It seems that most builders use traditional batt insulation in the walls and blown insulation in the attic. I have heard that foam insulation sprayed into the walls is far superior to batt insulation; is this correct? If so what are the cost differences per square foot between foam and batt insulation? I am considering building an ~ 2,200 sq. ft colonial and definitely want and need good windows and insulation to start with. Any advice or thoughts?? Any help is greatly appreciated.

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  2. muncybob

    muncybob Minister of Fire

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    It's to my undestanding that the spray foam is initially more expensive but where it shines is the elimination of drafts. I believe a lot of the foams are equal to or greater in R value per inch vs. fiberglass. This is great as long as you have some sort of fresh air system to a well sealed up house to avoid possible condensation/mold issues in the future.
  3. Ncountry

    Ncountry Member

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    I would highly recommend spray foam in the walls of a house not so much for the attic.Foam has close to double the R value /inch and stops close to all air infiltration . Not only is fiberglass not as good of an insulator but it is rarely installed properly(cut and tucked around wires, elect box,ect..). In the attic I would go with blown in fiberglass or cellulose . This would allow house to breath eliminating most moisture problems and reducing costs significantly.
  4. peakbagger

    peakbagger Minister of Fire

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    IMHO, I am not a fan of spray foam in walls with conventional framing and unless the installer does something special in the ceiling joists I dont think its worth the extra dollars. Obviously if you watch This Old House, it looks like the greatest invention of all time, but everytime I see them spray it into a house they level it with the studs and oh by the way, they get it installed for free or at a substantial savings. Even though the R value may be superior to fiberglass, the 2x6 framing is made of wood and it bridges from the outside wall to the inside with not a bit of foam to increase the R-value. Using 16" OC framing, that means 10 percent of each section of wall is the R value of wood. My preference is a 2x6 fiberglass insulated wall with 1" of foam board on the exterior or interior. Some folks advocate 2' on center framing with 5/8 inch sheetrock, to cut down on bridging but I expect that the studs would eventually telegraph.

    As for the argument that foam cuts down on drafts, thats true, if the contractor building the place doesnt do a good job crack sealing to begin with. Some states now require an air leak test prior to issuing a Certificate of Occupancy, I expect that contractors are a lot more careful in those areas (or push foam) as they typically dont get paid until the CO is issued. Realistically with air barriers, careful crack sealing, proper insulation installation and a real vapor barrier on the interior, drafts should not be an issue.

    Alternatively, skip the framing and go with stress skin panels, they go up super fast, they have no thermal bridging and they have incredible R-values.

    Of course anytime you use foam, be aware of carpenter ants. Granted a lot of contractors use termite barriers and claims it stops them, but I have heard of several cases where foam insulated walls were infested with ants despite the use of shields.
  5. btuser

    btuser Minister of Fire

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    I would strongly suggest sprayfoam, if only for the reason that after 15 years of residential construction I've NEVER seen a perfect vapor barrier. Either on the ceiling or especially in the walls, every time someone cuts an electrical box you get drafts.

    I think when building with spray foam, the advantages of the material should be used to change the way we build, therefore equalizing the costs. If you don't need a vapor barrier inside, or house wrap on the outside, or ridge vent or soffit vent or whatever you can save there and use it to pay for the extra cost of spray foam. I even think it makes the house stronger with the way it locks/glues the panels and studs together. I'm not sure, but I think a 2x4 wall 24" OC with spray foam will give you the same as a 2x6 wall 24" OC with conventional insulation.
  6. coolidge

    coolidge Member

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    If i were going to build a new house i would not skimp on the insulation part,it is something you cant change when the house is done without extensive remodeling. We all know oil is going to shoot back up when the economy recovers. Foam will be roughly three time more than fiberglass, but the house will be sealed and the foam will pay for itself with energy svings in four to five years. Yes you will need an air exchanger for the house to breathe, but as mentioned there are some savings on different building material that wont be needed. Also you could downsize you heating appliance if foam is installed.
  7. btuser

    btuser Minister of Fire

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    Good point on downsizing the heating/cooling need of the house. There is a little graph/chart that shows the law of diminishing returns when it comes to insulation, but you have to keep in mind that you're not looking for infinity but looking to keep your house warm/cool. If you can reach a certain point either through solar gain/extra insulation or whatever you might be better off with electric baseboard! Now you're talking 2 grand instead of 10 grand. Some say electric heat is more expensive but in a house with under a 20k heat load what's the difference?

    Maybe not in the attic/floors, but definately the entire building envelope.
  8. richg

    richg Minister of Fire

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    If you are building the house, I would pay the extra money and get spray foam in both the walls and attic.

    I was 1 micron from starting a spray foam insulation business in the fall of 2008, but backed off because the economy was crashing and the startup cost would have been close to 100K. That being said, there is simply no comparison between fiberglass batts, blown cellulose and spray foam. Many factors go in to this:

    1. Spray foam acts as a total air infiltration barrier. Fiberglass and cellulose will allow air pentration, whether it is in the attic or walls. Spray foam is like tank armor, nothing gets in or out.

    2. Spray foam has a much higher R value than fiberglass or cellulose. Most spray foams are at about R7 per inch, while cellulose is only at R3 and fiberglass about the same. Mind you, this is for CLOSED CELL spray foam, not open cell. I would not recommend open cell spray foam even though it costs a lot less.

    3. Total cost: expect to pay about $1.00 per board foot (12 inches by 12 inches by 1 inch deep). ISpray foam will cost a lot more in the beginning, but its stunning efficiency will quickly pay for itself via decreased utility bills and comfort in your living space.

    4. Teh most crtical space for insulation is the attic. Heat rises, and any penetrations into the attic are a major source of heat loss (and money loss). Spray foam knocks out this problem via its sealing properties.

    5. Here is an actual photo of a massive air leak in my attic. I was having problems with high heat bills and forst and mold on the attic sheathing. turns out that warm, most air was leaking into the attic via peenetrations. I pulled all the fiberglass, and found that many sections were blackened from dust-laden air moving through the fiberglass. I shot an inch-thick layer of spray foam across the attic floor and then sprayed a foot of cellulose on top. My utility bills have been cut in half.

    Geth the spray foam and don't look back.

    Attached Files:

  9. wenger7446

    wenger7446 Member

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    My wife and I put up an addition about two years ago and had spray foamed insulation installed. The best money we spent on the place.

    Just do it!
  10. Valhalla

    Valhalla Minister of Fire

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    Spray foam whenever possible! Nothing else is as
    effective.
  11. jimmy dean

    jimmy dean New Member

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    Lets first asses the two choices you have limited yourself to: Foam= $$$$$$$ per installed foot, most are not closed cell. Fiberglass=Thermal looping, wind washing R-value degradation. ONE MORE MISSING ALTERNATIVE!!! Cellulose insulation..
    Installed as DENSE PACK in the walls, stops air movement acts as an effective vapor retarder and has R-values up to 3.77 per inch. In the attic.. Seal all penetrations, I use mineral expanding gun-able foam, seal wall caps, plumbing holes, wire holes, seal chimney holes with metal not foam. If you want Ventilation (soffit and ridge or gable) "Prpa-vents" with tightly rolled fiberglass
    "plugs" pushed out to the outer edge of the eave walls backed with heavy packed cellulose. In your area R-45 value insulation in attic - 14-1/2" blown in BEFORE settling. Cellulose Dam at access hatch.
    If you want comfort without a big heat bill I just finished the third of six 12" roof framing, 12" walled, 1100 sqft all dense pack "cottages" on So. Burlington VT. Heated with Natural Gas 93% efficient thru the wall fireplaces as primary heat source, the heat is blown thru the HRV system in the houses, they are incredibility tight, warm and very efficient.
    If you have trouble finding a dense pack cellulose installer you might try contacting "National Fiber"..in Belchertown Ma. they may be able to refer you to a local installer.
    20 years of dense pack/air sealing and going strong.
  12. SolarAndWood

    SolarAndWood Minister of Fire

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    I assume this is if you have a guy come and spray a large area? Seems like polyiso board is half the price and if you are remodeling you can do it as you go as opposed to having the whole house opened up? 3 sheets of 1 7/8" in the 2x6 stud bays, Tyvek outside the sheeting and 1" over the Tyvek gets you in the R45 neighborhood and should be airtight with the bridging issue minimized? Then maybe a little DIY spray foam for those places that board would be tough to get in tight? It is unfortunate that 1 7/8" is more than twice the price of 1".
  13. richg

    richg Minister of Fire

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    On an "inch vs inch" basis, polyiso board does ahve the same R value of spray foam, perhaps even a little higher as it is manufactured under tightly controlled conditions in a factory. On site spray foam cany vary a bit if the proportioner is off, drums aren't fully mixed etc. Polyiso also has a layer of radiant barrier applied which is useful for attic installations. However, the value of on-site spray foam is the absolute, total air infiltration barrier you get. Yes, you can cut polyiso boards to fit a cavity and then use gun foam to seal the gaps. That will still not even come close to spray foam in terms of R value and air-sealing properties. I went through this entire debate in my head for months before biting the bullet and going with spray foam. Most contractors will have a minimum project size which is usally $2000.00 cash. In these dreadful economic times you might be able to find someone who will do it for far less. Some guys have a rig especially for small jobs, which is the Graco E-10. They can come in, shoot and scoot.
  14. JayDogg

    JayDogg Member

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    I just built a 3,000 sq. ft. colonial over the past summer, we live in western ma where it gets to the teens every night in the colder months. I did the Spray Cellulose and couldnt be happier. It was quite a bit cheaper than the Spray foam and dont believe it is less of a product. It still fills all the cracks and gaps between electrical boxes..etc. One key to having a tight house is to go around with some "Great Stuff" for windows and doors and fill the areas around the windows and doors before the house is sheet rocked, you will get a good draft in these areas if its not done. You could also get a bunch of silicone caulking and seal the bottom and top plates around the exterior of the house. We could not be happier with the insulation in our house, and it is very quiet in there as well. I have built about 6 houses over the years, and this one if buy far the best choice of insulation for me. I have seen the spray foam insulation as well and it definitely does do a great job of insulating (not sure if I would say a better insulator that cellulose) but the price of cellulose compared to foam is probably 30% cheaper.
  15. hkillam

    hkillam New Member

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    Sprayed closed cell has an additional benefit not yet mentioned; flood survivability. I understand in some flood prone areas, this is the norm for insulation in new construction, far lower rebuilding costs as the insulation doesn't need to be replaced, and actually adds some rigidity to walls when the drywall fails.

    However, be sure you've got all your electrical runs just the way you want them, cause you can't really pull new lines within a closed cell wall like you can in fiberglass batts. Not sure, but some municipalities may require sealed (foam proof) conduit for all walls where foam will be sprayed. Again more expense, but less expense later if you ever need to pull replacement wiring within existing conduit.

    Personally, in new construction, I'd go foam for the reasons already listed in previous posts. I do agree with the drawback of thermal bridging in studs, but that is present with foam, blown cellulose, fiber batts, etc. Some rigid foam board between outside exterior walls and the outside finish addressed this, and makes a lot of sense, plus doesn't need much trimming versus the rigid foam boards cut to wall cavities.
  16. semipro

    semipro Minister of Fire

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    As muncybob and others alluded to, don't underestimate the value of inhibiting air infiltration. You can insulate a house really well and still have a cold and drafty house and high utility bills if its not airtight. It helps to keep critters out too. Don't worry about making it too tight as you can always add a heat recovery ventilator and then control the quantity and quality of air that enters while recovering the heat. That's nice for allergy sufferers too.
  17. prink3

    prink3 Member

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    I recently did a major addition and remodel in my house. I had the same conflict with performance over price. I went with batt in the studs, 1/2" sheathing, and 1" Polyiso board on the outside. The reduction of bridging is big, but reducing infiltration is bigger. I addressed this by caulking and can foaming everything in the walls, caulked and taped the board insulation, plus I used a liquid applied (like paint) air barrier on the outside of the sheathing. It was a commercial product called Sto Emerald coat, but I found several others. I went with this package because the performance was close to sprayed foam, but much of it was DIY, and was 20% the cost of foam. If I could have afforded a bigger budget and was paying for an installed insulation package, I probably would have gone with foam.

    Regardless of your decision it is still important to seal between floors and walls well, no more than one vapor barrier in a wall, and use efficient framing that causes less thermal bridging.
  18. jimmy dean

    jimmy dean New Member

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    What all this chin music sugars out to.. using dry dence pack cellulose (and airsealing open attics and around windows & doors) I can get a house 99% as tight as a foam house, with out converting food (soy) or OIL - anybody making new oil latly? for about half the $$$$ for new houses and 1/3 the $$$ for retrofit. Oh Ya Bug and mice hate cello, while foam and that pink fuzzy stuff provide warm wonderfull homes for them. Build'em tight.. Vent'en right- Jim Fitsgerald (the master densepack cello man).
  19. richg

    richg Minister of Fire

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    Good thread here. We have listed the pros and cons of the major types of insulation, and now it's up to the buyer/user to make the decision. Which ever way he goes, I am heartened to see people paying so much more attention to energy conservation. Group hug time. :p
  20. SolarAndWood

    SolarAndWood Minister of Fire

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    Its amazing how much more you pay attention to it when you are producing the fuel instead of just paying another bill.
  21. ChillyGator

    ChillyGator New Member

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    Had open cell foam sprayed under my wood floors (open crawl space-no insulation prior) yesterday. Called for a minimum 3.5" between floor joists but it looks a lot more like 5"-6" was actually put up :coolsmile: Actually had some foam come up thru my heart pine floors in two places :bug:

    Already could tell the difference, 48* outside/furance set at 63* inside/actually temp was 65.5* inside @ 6:00pm last night (had left the wood stove stoked up prior to leaving for work yesterday). Last night temps got down to 30* but I had to run much smaller fires to keep my living room under 80*

    I don't think the furnace ever came on last night. WOW this is gonna save me big $$ on propane and reduce wood consumption....LIFE IS GOOD!

    will try to add pics when I get the chance.
  22. caber

    caber New Member

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    We just put on an addition. We wanted to do the spray foam but absolutely choked on the cost. We did the framing at 2x6 and to fill it up was outrageous. They also suggested 1-3 inches of foam and additional bats to get the R value up and the was only slightly less cost prohibative. We ended up with the dense pack cellulose. Great product. Slightly more than fiberglass, great barrier.

    ChillyGator - we have the same issue as you did with the original part fo the house. It is up on an open pier foundation. There are batts in the joists, but they don't do a great job of keeping the floor warm in the winter. When we get a day where the wind is in the 20s and up, the wind really pushes the cold air thru the batts and chills the floor. It's the biggest heat suck in the house. We had a company look at it with the thought of doing spray foam to seal the floor and they claimed it would be too difficult to install. The guy said since they would be crawling around they could not keep a steady and open stream and the nozzle would keep clogging and we would pay a fortune in nozzles. I'm looking at alternatives to seal up the underneath. My current idea is insulated sheathing in the bays with spray foam around the edges, followed by a layer of batts and then a vapor barrier. I'm working on getting concrete blocks to build a wall around to make it more of a crawl space versus open pier.

    Anybody have experience with the DIY spray foam kits?
  23. ChillyGator

    ChillyGator New Member

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    At first I was concerned that the installer could not get to all of my crawlspace (very tight in the front of the house) but he assured me after looking at it that "we grease em up and slide em in very tight places".......he was not kidding!

    First looked into this last summer and was quoted $1.60 sq ft for 3.5" of foam.......when I checked back after the first of the year I was quoted $1.30 sq ft and interest free financing for a year.

    I think my guy wanted work for his crew and to get the word out in my area concerning retrofitting older homes. Worked for me!
  24. ilateapex

    ilateapex Member

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    Another option is to do what is called a "flash and batt". This is where they come in and just put a thin coating of the foam, say 1/2" or so to seal everything up and then install traditional fiberglass batts. This also can be done using netting and loose fill if you choose. Another thing to consider is to make sure all the HVAC and Duct work is in the conditiond space. Makes a big difference. On a current project we are doing, we have to foam the roof deck so that attic is part of the conditioned space just for the HVAC. And install and ignition barrior as there is no sheetrock over the insulation.

    Good Luck

    Michael
  25. coolidge

    coolidge Member

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    Caber, If your going with blocks around the perimeter you could spray them instead of the floor. Flash-n -batt syatems have there place in the insulation world. I talked to a man with extensive knowledge of sprayfoam and he was a little concerned with spraying half to one inch of foam and then fiberglass or cellulose. The condensation point could very well be between the two, which would really suck.

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