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foamitgood
Registered Users
Posts:4
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| 08/19/2008 10:50 PM |
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You only get one shot at insulating your house, so make sure its done right. Basement first, regular concrete wall system with 2x4 framing held away from wall one inch. Then .5lb foam sprayed directly to concrete from floor to ceiling sealing up any holes to the outside. Main floor 2x6 cavities filled with foam,all stud junctures caulked and foam around all windows and doors. In the attic after sheetrock is up look down around any penetrations that you see daylight and seal them up. Cellulose or fiberglass can then be piled high at a low cost with with reasonable performance. All mechanicals need to be sized properly,very important. A house foamed in this manner should run around 5500$ not a bad price to pay for an extremely energy efficient and comfortable house. |
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Mark Fleming
Registered Users
Posts:188
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| 08/20/2008 6:30 PM |
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I have always been amazed that the fiberglass insulation industry has gotten essentially a free ride for so long. Where are it's defenders and proponents? Where are those singing its praises? Not on the internet, because its advocates are the board of directors and shareholders. They have somehow convinced the ICBO, ORNL, and local building inspectors that 3 inches of puffy pink is the God-given metric for R-13. It might be R-13 in 1/10th of most installations.
I'm another fan of spray foam, although quality is expensive. However, it can be used judiciously, AND THEN FIBERGLASS WORKS. Use 2x6 walls with an inch or two of spray foam. Make sure that the studs get foamed, but not the faces. Then, you have prepared a wall in which puffy pink can actually work. No air infiltration (but you pay for this). No stud slivers creating airways along the already low R value of the stud (but you pay for this). No moisture issues or vapor barrier problems (but you pay for this).
Mark |
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kwalla101
Registered Users
Posts:12
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| 08/22/2008 12:37 AM |
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Mark-
when you say quality is expensive, are you talking about the product or the application? Do you have any thoughts on which DIY spray foam products are the best or would you only recommend having it done by a pro? I'm planning on exactly what you recommend-- an inch or so of foam against the sheathing and then fiberglass or cellulose for the rest of the cavity. Plus foam in all headers and in the attic against the 2nd floor ceiling and all penetrations. I've used spray foam in small quantities, mostly for installing retrofit windows-- it's a pain to work with but it seems doable and a good way to save money; any thoughts?
Oh, and can you explain what you mean by foaming the studs but not the faces? Didn't follow you there.
Many thanks-
Kevin |
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Mark Fleming
Registered Users
Posts:188
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| 08/22/2008 10:48 AM |
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Kevin,
I shot a pallet of TigerFoam on a recent DIY project, the best priced stuff I could find (check Ebay for auctions). Since shipping of the "kits" is expensive, I had a pallet delivered. It was actually for another project but, long story short, I used it on living space above a new construction shop/garage. My father-in-law just spent two weeks in my "storage space" and found it extremely comfortable and almost too quiet. Can't hear the wind, rain, sea gulls, etc.
Application was messy. I got some overspray on my glasses, so there's $100 in unforeseen costs. Wear a Tyvek suit, spray painter's gear, throwaway shoes, etc. (especially when doing overhead). It was an experience, but I'd definately get a professional bid next time, even though I'd probably pay $200 in travel time to get somebody out here. I ended up throwing 12 empty "propane tanks" into the dumpster when finished. Not very green. The professionals use a machine and clean up when they're done. Lots of benefits besides just figuring the cash outlay. Even though it was messy, the little bit of fiberglass I installed was almost as creepy. When the sun comes through a window and you can see all the microscopic glass floating in the air, yeck. How many years before that's all gone?
Studs are the R value weakness in the wall. To the extent that some "overspray" ends up on the sides of the stud, it greatly lessens the stud's heat leak. Plus, it creates a smooth, tight surface for the fiberglass to butt up against. If you spray so much that it gets on the drywall "surface" of the stud, then it has to be scraped off before drywalling.
I also did the rim joist in the basement. That's probably the type of project best left to the kit application.
Mark |
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kwalla101
Registered Users
Posts:12
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| 08/22/2008 6:13 PM |
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| Mark-- what an awesome answer! THanks! |
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foamitgood
Registered Users
Posts:4
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| 08/24/2008 11:21 PM |
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| Aword of caution when spraying 1 inch of foam, then using filterglass to fill the rest of the cavity. What happens when it gets extremely warm or cold is that the dew point is not inside the foam,but in the fiberglass or on the face of the foam. This leads to condensation and moisture inside your wall cavity, and since the foam air sealed the wall now the fiberglass has no way to dri out. Closed cell foam should be sprayed to a minimum of 2 inches ot prevent condensation especially in the northern climates whare it gets below zero for extended periods of time. If you have the chance to use foam in your home take the plunge it is one of the best investments you will make. Think of it like this,if you have two boxes bolth the same size ,one has 20 holes and the other has 4 holes which box will be eiser to heat and cool. Insulation is the most overlooked aspects of building when in reality it is one of the most important. Fiberglass may be cheap but it costs you every day your house is standing so due it right and smile when you get your utility bill instead of picking your jaw up off the floor. |
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kwalla101
Registered Users
Posts:12
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| 08/25/2008 1:34 PM |
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Foamitgood- what would you suggest for this strategy in a warm climate (Central CA, zone 9b)? My intention is to put an inch of spay foam in the wall cavaties against the sheathing and fill the rest with FG or cellulose. On the outside of the sheathing will be 1" foamboard (also closed cell). Do you think that the layer between the foams-- basically just the sheathing, though the studs to some minor extent, will become saturated with moisture? After that inch of foamboard there will be a radiant barrier house wrap and finally lath and plaster firred out to make sure there's a minor air gap there. Any thoughts/suggestions/warnings?
Many thanks-
Kevin |
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Boontucky-girl
Registered Users
Posts:87
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| 08/25/2008 3:57 PM |
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Thanks for all of the info. This is what I've asked on another thread. I am still pushing to go ICF all of the way, even went as far as to tell the ICF contractor that I only have x amount of money, and if hecan figure out how we can do it, we will, otherwise it's regular build for us. But I really want to make sure that just because we go stick we can't make it energy efficient. I live in Iowa, I'd like to know which option is best:
2" foam over exterior sheathing with 2" of closed cell spray foam in 2x6 cavity and fiberglass over that. Open cell foam under roof sheathing. Would cavity full of closed cell foam be better? (but probably costs too much)
or
2" foam over exterior sheathing with 2x6 cavity full of open cell foam, with open cell foam under roof sheathing.
Also, is the soy based foam any good?
Thanks!
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Bruce Frey
Registered Users
Posts:66
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| 08/25/2008 5:11 PM |
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For those of you debating open cell spray, closed cell spray, conventional fiberglass, vs. ICF, SIP, etc., etc, you owe it to yourselves to spend some quality time at http://www.buildingscience.com/bsc/
A lot depends on where you live and what kind of wall construction and exterior finish you want to use.
Bruce |
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foamitgood
Registered Users
Posts:4
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| 08/25/2008 10:35 PM |
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| The price of 5.5 inches of open cell usually costs less than 2 inches of closed cell and thats before you buy the fiberglass. Why pay more for an R-13 of foam when you can have an R20 of foam for less cost. If your worried about the thermal transfer of the studs use 1 inch foam board over the sheeting this will give you an incredibly energy efficient house. |
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Mark Fleming
Registered Users
Posts:188
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| 08/27/2008 11:41 AM |
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Ffoamitgood said "Aword of caution when spraying 1 inch of foam, then using filterglass to fill the rest of the cavity. What happens when it gets extremely warm or cold is that the dew point is not inside the foam,but in the fiberglass or on the face of the foam."
I've heard of this "issue" before and I think few, if any, humans live in climatic conditions where the dew point would be on the inside through an inch of foam. When you put your cold beer in a 1/4th inch neoprene bottle holder on a muggy day, you don't get condensation on the holder despite a 50 degree delta T. When I put dry ice in a 1" thick foam cooler in Arizona, I don't get condensation on the outside of the cooler. Maybe a sauna at the North Pole using only 1" of foam? It could happen in theory, but I've never seen any indication of it happening in reality. Of course, a poor foam job or heat sinks passing through the foam (generally sheathing nails that missed the stud) could change things. With 2 inches of foam (needed for 2x6 construction with foam and 2x4 fiberglass), I really can't see condensation as an issue.
Mark |
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Boontucky-girl
Registered Users
Posts:87
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| 08/27/2008 2:18 PM |
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| Very good information! Thank you. What about the basement? If ICF works with insulation on both sides of the concrete, why can't I do the same thing with a regular concrete wall and use foam sheets on the inside and outside? If I go with ICF, it is about twice as much as the regular bid, but that has partly to do with the fact that with ICF, even the walkout wall is concrete, where with the regular case, the whole back side of the house would be stickbuilt. |
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