Vented Attic Spray Foam | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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overhaulin63 Posted: Nov 07, 2016 02:54 PM	Vented Attic Spray Foam Hey Mason, I recently built a large garage and I wanted to spray foam it all including the trusses and the ceiling/sheeting above it. Can I use spray foam for this application and if so what do I do with the vented soffits and the ridge vent? Do I cover them too? Thanks, Kirk
mason Posted: Nov 07, 2016 03:59 PM	Is the garage going to be conditioned? If so, then Yes, you cover the ridge vents and place a cover board to separate the soffits from the interior, then spray foam to it and the underside of the roof deck. The soffits themselves can be left open so long as the air can circulate within the uninsulated portion of the eaves. You want to make sure that no warm air from the interior of the garage hits the underside of the roof deck so the cover board is on the outside portion of the wall next to the soffit. If you are in cold country, that would lead to ice damming. email me at masonknowles@aol.com and I can send you a few articles on unvented vs vented attics.
overhaulin63 Posted: Nov 10, 2016 10:45 AM	Hi Mason, I live in Ohio and my garage is 32x60, 12’ ceiling and 18’ at the peak. The garage also has radiant floor heat. The garage has 2-16x10 and 1-10x10 doors plus a man door. I was concerned that if I enclose the ridge vents during the Summer months there would be no way for heat to escape the building and I would cook the ceiling. I had a condo where the soffits had been blocked off ventilation and the roof got cooked and became delaminated. I don't understand the difference. I still haven’t grasped how enclosing the vents will not cook the roof. Help! ???? Thanks again for your time.
mason Posted: Nov 13, 2016 01:20 PM	I haven't received your email to send you articles on unvented vs vented attics. Plus haven't heard from you. If you have not HVAC equipment in the attic, then you insulate the floor of the attic not the ceiling. Then you vent the attic. If you have HVAC equipment (ductwork etc.) in the attic then the most energy efficient way is to have an unvented attic. There is no way to "cook" the roof when using unvented attics. Something else went wrong with your roof. I have tons of data, field history and research to back that up. Email me and I will send it.

Author

Comments

overhaulin63

Posted: Nov 07, 2016 02:54 PM

Vented Attic Spray Foam

Hey Mason,
I recently built a large garage and I wanted to spray foam it all including the trusses and the ceiling/sheeting above it. Can I use spray foam for this application and if so what do I do with the vented soffits and the ridge vent? Do I cover them too?

Thanks, Kirk

mason

Posted: Nov 07, 2016 03:59 PM

Is the garage going to be conditioned? If so, then Yes, you cover the ridge vents and place a cover board to separate the soffits from the interior, then spray foam to it and the underside of the roof deck. The soffits themselves can be left open so long as the air can circulate within the uninsulated portion of the eaves. You want to make sure that no warm air from the interior of the garage hits the underside of the roof deck so the cover board is on the outside portion of the wall next to the soffit. If you are in cold country, that would lead to ice damming.

email me at masonknowles@aol.com and I can send you a few articles on unvented vs vented attics.

overhaulin63

Posted: Nov 10, 2016 10:45 AM

Hi Mason,
I live in Ohio and my garage is 32x60, 12’ ceiling and 18’ at the peak. The garage also has radiant floor heat. The garage has 2-16x10 and 1-10x10 doors plus a man door.

I was concerned that if I enclose the ridge vents during the Summer months there would be no way for heat to escape the building and I would cook the ceiling. I had a condo where the soffits had been blocked off ventilation and the roof got cooked and became delaminated. I don't understand the difference.

I still haven’t grasped how enclosing the vents will not cook the roof. Help! ????

Thanks again for your time.

mason

Posted: Nov 13, 2016 01:20 PM

I haven't received your email to send you articles on unvented vs vented attics. Plus haven't heard from you. If you have not HVAC equipment in the attic, then you insulate the floor of the attic not the ceiling. Then you vent the attic. If you have HVAC equipment (ductwork etc.) in the attic then the most energy efficient way is to have an unvented attic.

There is no way to "cook" the roof when using unvented attics. Something else went wrong with your roof. I have tons of data, field history and research to back that up. Email me and I will send it.

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