Air Barrier at What Thickness? | Insulation/Energy/Building Envelope Q&A | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Trey Gibson Posted: Dec 05, 2007 07:31 PM	Air Barrier at What Thickness? I am running up against some competitors selling 1/4 to 1/2" of closed cell foam and putting either a batt or blown fiberglass on top of it and claiming they are getting an air barrier with the foam and higher r value over all while still being cost effective. I am looking for some solid data that shows at 1/4 to 1/2" the foam is not a complete air barrier. Which I believe is true. Does anyone know where I can find this info? Thanks
Dwight Thevenot Posted: Dec 06, 2007 08:27 PM	I believe closed cell will be effective at that depth. But, let the homeowner know that the fiberglass is not going to be R-13/R-19 due to being compressed, it will shrink overtime, and lose R value. You should be able to install .5# for just as cheap. I ran into this issue up in Indiana. Plus, disprove the Rvalue myth. NexGen makes me laugh when he states we as Spray Foam foam contractors can sell them R2 that will save 50% in energy. They want to sell R16 that will cost twice the energy price. What would you buy? R value, or energy reduction. Also the fiberglass will reintroduce dust into their living space. Good luck Foamer, Nutech Foam
Posted: Dec 09, 2007 02:57 AM	yes indeed, 1/4 to 1/2" closed cell could indeed invoke an air barrier...in fact house wrap is marketed as an air barrier (luv them mechanical fastners!!!) and a meticulous applicator could accomplish such with can foam, acrylic caulk and house wrap...but not as good as the side to side seamless, monolithic air barrier invoked by a well applied spray foam application. i inform my customers that a "building envelope" application will NOT afford them the energy savings of a FOAM INSULATED HOME. it will, however, allow the LESS EFECTIVE insulation product (ie: filterglass/shreadedpaperulos)to perform closer to its labled r value when exposed to adverse conditions, cold temps and wind wash,,, the conditions which can reduce the labled rvalue of an r19 friction fit batt to an rvalue of around r10 with even further degradation if the batt was "custom fit" to a framed cavity.... the "building envelope" system will help control the uncontrolled air movement into and out of the structure allowing the structures mechanical systems to perform with maximal efficiency and performance. the added rvalue is about a wash if you look at the reduction in the rvalue of the tradional products rvalue,,so i dont promote this application as an r value enhancement but rather as a performance enhancement. it works well! we have blower door tested many of our BE homes. most are hybrid apps (BE with truss heels blocked only, no foam in lid or attic) these have tested as low as the testor has ever seen,,,consistently! did i say we caulk a doulble studs, plates, insulate all interior walls for sound, foam caulk all penetrations not addressed by spray foam app,, and otherwise detail these places out...it works! my BE is a 3/4 to 1" app on the perimeter sidewalls with open pocket corners filled as well as headers to full depth and other "difficult to insulate areas" shot out to r19. any less depth and i loose as i we just like the creativity the 1" allows us in our applications and this is what we would be putting down,,also,,more importantly,,i am in this to make a profit,,and this is what it takes to keep me chasing my shadow up and down the interstate... the BE works,,,well,,,it will not afford hugh energy savings,,, if the customer wants cheap,,,they will get cheap,,and cheap reaps cheap.. cheap cheap!!

Author

Comments

Trey Gibson

Posted: Dec 05, 2007 07:31 PM

Air Barrier at What Thickness?

I am running up against some competitors selling 1/4 to 1/2" of closed cell foam and putting either a batt or blown fiberglass on top of it and claiming they are getting an air barrier with the foam and higher r value over all while still being cost effective.

I am looking for some solid data that shows at 1/4 to 1/2" the foam is not a complete air barrier. Which I believe is true.

Does anyone know where I can find this info?

Thanks

Dwight Thevenot

Posted: Dec 06, 2007 08:27 PM

I believe closed cell will be effective at that depth. But, let the homeowner know that the fiberglass is not going to be R-13/R-19 due to being compressed, it will shrink overtime, and lose R value. You should be able to install .5# for just as cheap. I ran into this issue up in Indiana.

Plus, disprove the Rvalue myth. NexGen makes me laugh when he states we as Spray Foam foam contractors can sell them R2 that will save 50% in energy. They want to sell R16 that will cost twice the energy price. What would you buy? R value, or energy reduction. Also the fiberglass will reintroduce dust into their living space.

Good luck Foamer,
Nutech Foam

Posted: Dec 09, 2007 02:57 AM

yes indeed, 1/4 to 1/2" closed cell could indeed invoke an air barrier...in fact house wrap is marketed as an air barrier (luv them mechanical fastners!!!) and a meticulous applicator could accomplish such with can foam, acrylic caulk and house wrap...but not as good as the side to side seamless, monolithic air barrier invoked by a well applied spray foam application.
i inform my customers that a "building envelope" application will NOT afford them the energy savings of a FOAM INSULATED HOME. it will, however, allow the LESS EFECTIVE insulation product (ie: filterglass/shreadedpaperulos)to perform closer to its labled r value when exposed to adverse conditions, cold temps and wind wash,,, the conditions which can reduce the labled rvalue of an r19 friction fit batt to an rvalue of around r10 with even further degradation if the batt was "custom fit" to a framed cavity.... the "building envelope" system will help control the uncontrolled air movement into and out of the structure allowing the structures mechanical systems to perform with maximal efficiency and performance.
the added rvalue is about a wash if you look at the reduction in the rvalue of the tradional products rvalue,,so i dont promote this application as an r value enhancement but rather as a performance enhancement. it works well! we have blower door tested many of our BE homes. most are hybrid apps (BE with truss heels blocked only, no foam in lid or attic) these have tested as low as the testor has ever seen,,,consistently! did i say we caulk a doulble studs, plates, insulate all interior walls for sound, foam caulk all penetrations not addressed by spray foam app,, and otherwise detail these places out...it works!
my BE is a 3/4 to 1" app on the perimeter sidewalls with open pocket corners filled as well as headers to full depth and other "difficult to insulate areas" shot out to r19. any less depth and i loose as i we just like the creativity the 1" allows us in our applications and this is what we would be putting down,,also,,more importantly,,i am in this to make a profit,,and this is what it takes to keep me chasing my shadow up and down the interstate...
the BE works,,,well,,,it will not afford hugh energy savings,,,
if the customer wants cheap,,,they will get cheap,,and cheap reaps cheap..
cheap cheap!!

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