Getting R-30 in an attic suite with 2x6 ceiling rafters
Better than spray foam (thermal break and relatively consistent R-30+). Here's how to use 3 layers of 2 inch polyiso foam board to meet code and keep your new upstairs cozy.
**UPDATE WATCH THIS BEFORE YOU CUT FOAM https://youtu.be/Z292iuV91hA
I used a 2 inch rigid polyiso foam (GAF Energyguard) I got from a local roofing supply company (ABC Roofing). It is really the type of foam they use on commercial roofs beneath a membrane. I believe mine was made by GAF, and ran me about $18 per 4x8' sheet. I cut two layers to fit in the rafter bays (so that's 4 inches), spaced 1&1/2" away from the roof-deck with scraps of 2x4s (which maxed out my 5 1/2" inch rafters). Then I put another layer across the rafters, which made a total of 6 inches of polyiso. Each inch was R-5.4, so the total R value of all 3 layers was 32.4. Wherever there were gaps, I squirted some Great Stuff in, then shaved the overflow back with a flush cut hand-saw.-- Yes, it passed insulation inspection.
Disclaimer:
If you choose to imitate, duplicate or copy anything you may have observed in these videos, you do so at your own risk. The creator of this content does not take any responsibility for any action taken as a result of the information or advice on this YouTube channel (or other platforms) and shall not have any liability in respect of any injury or damage that may result.
Видео Getting R-30 in an attic suite with 2x6 ceiling rafters канала DIY Dave
**UPDATE WATCH THIS BEFORE YOU CUT FOAM https://youtu.be/Z292iuV91hA
I used a 2 inch rigid polyiso foam (GAF Energyguard) I got from a local roofing supply company (ABC Roofing). It is really the type of foam they use on commercial roofs beneath a membrane. I believe mine was made by GAF, and ran me about $18 per 4x8' sheet. I cut two layers to fit in the rafter bays (so that's 4 inches), spaced 1&1/2" away from the roof-deck with scraps of 2x4s (which maxed out my 5 1/2" inch rafters). Then I put another layer across the rafters, which made a total of 6 inches of polyiso. Each inch was R-5.4, so the total R value of all 3 layers was 32.4. Wherever there were gaps, I squirted some Great Stuff in, then shaved the overflow back with a flush cut hand-saw.-- Yes, it passed insulation inspection.
Disclaimer:
If you choose to imitate, duplicate or copy anything you may have observed in these videos, you do so at your own risk. The creator of this content does not take any responsibility for any action taken as a result of the information or advice on this YouTube channel (or other platforms) and shall not have any liability in respect of any injury or damage that may result.
Видео Getting R-30 in an attic suite with 2x6 ceiling rafters канала DIY Dave
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