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While at a home show recently, a representative for an icynene foam installer told me that if I used their product for wall installation, I should only use 2×4 walls instead of 2x6s. He said that due to the sealing qualities of the foam, the house would be just as warm, even though the R value is quite a bit less. The money saved using 2x4s would help pay for the foam. Does this make sense? He also suggested spraying 2″ of the foam on top of the ceiling drywall panels, then finishing the ceiling insulation with blown in product. He said use the ceiling foam for a seal, and don’t use any vapor barrier, on the walls or the ceiling. What experiences have others had?
Thanks, Bob (Indiana)
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I used Icynene on certain parts of my addition.
Blew in a r-13 on ceiling and under floor of an exposed porch. It does stop all air movement. The installer made similar claims to what you heard. I can easily believe that a 3" layer of icynene insulates better than the R-19 batt walls. There are no voids, and no errors. I couldn't afford to blow it on the walls, so I used it where it would be difficult (because of my construction) to insulate well with batts. I then used R-30 on top of the R-13 icynene.
*LarryJust curious... when the icynene was sprayed on the ceiling, was that on top of the ceiling and in the attic??
*I thought icynene had a higher R value in a 2X4 wall than a 2X6 wall with batt insulation. Better check their literature out. The installer I talked to also suggested 2" in the attic (On i topof the drywall) to seal the attic up, then blown on top. I really like the idea of icynene, but it's awful danged expensive. Might talk to your HVAC guy about it - They might recommend a smaller heating unit with icynene, but you might also need a heat exchanger to get some fresh air in if you use icynene all over.
*Yeah, first I put the ceiling drywall up, taped it and then had the 3-4" of Icynene in on top of the drywall. Really sealed it up tight. Price around $1.30 a ft^2.Batt insulation quotes it's maximum performance (eg, R-13, R-19). Icynene easily achieves it's max. peformance, not sure how hard it is to achieve R-19 with R-19 batts, but the FHB articles on installing Batts shows some pretty good attention to detail.I wouldn't spend money on R-30 in icynene, but I'm on a budget (3200ft^2 using only excess cash from paychecks, no construction loans) and still felt that the R-13 was worth it.