EcoRenovator - View Single Post - Building an attic door insulation enclosure. Thoughts/Help needed...

MN Renovator · 10-11-13, 11:16 PM

I don't see how the batticdoor thing could possibly be any more than about maybe R30 if it used two layers of the more dense R15 3.5" fiberglass. There is no way it could even be getting that because they don't insulate the sides of it at all. That product is just a lie to try to sell something to people who want to meet code in new construction, I think. Not sure but the product is junk in my opinion.

I think that 4 inches of XPS(blue or the pink) foam would be plenty. That's R20 and in general its a small area so even if it is less than what you have in the rest of your attic the difference won't be huge, it will be far less heat loss/gain than even one small window in the house. Your walls probably have R13 or R19 of fiberglass in them depending on how thick they are. The important part is getting a good air seal between the joints in the foam and a good gasket seal at where this will sit.

10-11-13, 11:16 PM	#9
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	I don't see how the batticdoor thing could possibly be any more than about maybe R30 if it used two layers of the more dense R15 3.5" fiberglass. There is no way it could even be getting that because they don't insulate the sides of it at all. That product is just a lie to try to sell something to people who want to meet code in new construction, I think. Not sure but the product is junk in my opinion. I think that 4 inches of XPS(blue or the pink) foam would be plenty. That's R20 and in general its a small area so even if it is less than what you have in the rest of your attic the difference won't be huge, it will be far less heat loss/gain than even one small window in the house. Your walls probably have R13 or R19 of fiberglass in them depending on how thick they are. The important part is getting a good air seal between the joints in the foam and a good gasket seal at where this will sit.