I have been contemplating using sprayed-up polyurethane foam insulation for a remodeling project of a couple of rooms in a 1910 vintage house. The remodel will require gutting to the studs. I have had quotes from several companies. I also looked into purchasing foam kits and doing it myself. I was amazed to find that there is very little savings by doing it myself. However, I also looked at the price of foam board, particularly Tuff-R and Super Tuff-R, and find that I can purchase this product for about half the price per cubic inch than the sprayed-up version. Here is what I am thinking.
I would buy 2″ Tuff-R (R factor of 13.8), and cut it to fit the cavity between the studs, making it about a quarter inch narrower and shorter than the space between the studs and plates . I would then place the foam board between the studs (the nails from the siding will hold it in place) and used canned foam to fill and seal the quarter inch space between the board and the studs, plate, etc. Voila! I have essentially the same thing as if I hired a contractor but at half the price. And much neater! Any little nooks and cranies can be filled with canned foam. One could even use canned foam as a sealant/adhesive to join pieces of foam board, making for less waste. I plan to add strips to the studs to make a 6″ deep cavity, and probably will fill the remaining space with fiberglass batting.
So what do you think? I am not doing this job for profit, so the extra labor is not an issue. And I don’t want to hear how cheap I am.
Thank you.
Replies
Would work in theory. One downside is the fact that Tuff-R is poly isocyanurate foam with foil on both sides. Poly iso is open celled and will absorb water if the foil facing is punctured which will be the case if you press it into your stud bays against the siding nails. When this stuff gets wet, it loses much of its R-value and it can stay wet for a long time.
If it were me, I'd use extruded plystyrene foam panels (blue or pink board). Extruded foam panels are closed cell and won't absorb water, plus less expensive yet.
If you are going to fatten the walls anyway, maybe consider high density FG batts in the existing stud cavities, then attaching continuous layer of foam panels to the inboard side of the studs. Then horizontal strapping over the foam layer to attach drywall. This technique will help minimize thermal bridging through the studs.
Thanks for the reply. I will certainly consider the blue and/or pink board - an excellent suggestion for which I thank you. As the building has 1 x tongue and groove sheathing, red rosin paper and cedar shingles siding, all 100 years old and not very well sealed to say the least, I was thinking that putting the foam board directly against the sheathing would create a barrier against air leakage. If I put fiberglass batting next to the sheathing, I think it would be less effective because of the air leakage. I assume the foil faces have some benefit re radiant heat, but I don't know how significant it is in the overall scheme of things. The pink and blue board don't have that feature.
I don't have alot of time to hunt up past discussions but there are many if you use the couple of search functions on the site. I have hit or miss luck with it some times but try a couple of different key words.
Scroll to bottom of thread on left and there is the first search.
The other thing that works good is asking any body to steer you to past threads that they know of. Lots of helpful folks around.
It also doesn't sound like your gonna be getting any water problems, from what you describe.
Thanks. I found it.
Top of left column is the advanced search which has a better chance of working
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One of those things I try not to figure out, but some times the bottom one works great and other times not?
Almost like I have exceeded my limit of questions for a period and no more answers.
And Yes I have to invest more time in the effort to get the info then just thinking it will just appear.
The way you propose is fine.The pink or blue are a closed cell rather than open cell, but only R5 instead of your R7 per inch.Radiant foils help when there is an inch of free air space in front of it, as you appear to be giving it
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Thank you.