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MN Renovator · 04-20-12, 08:58 PM

I always thought the idea of more insulation in the roof came from the vented aspect of the roof increasing the surface heat conductivity of the insulation since there is air flow directly over it requiring more insulation while the walls are sheated and essentially have a layer over them. In the winter with the ceiling having the hottest air that supposedly you'd want more insulation there. Not to mention it's easy to load a whole bunch of loose fill cellulose up there. In my case it's about the only place I can add cellulose to my current house without tearing out drywall, which makes it a large and easy retrofit opportunity. As long as all air sealing opportunities aren't missed before loading a pile of treated paper up there, it's about one of the only options for adding R-value for most. In a new house R60 might be more than enough, depends upon the standards for energy use that someone is going after, I'll have to read those sections of my Manual J again and read the factors on heat loss through the attic versus the walls so I can make comments about what ASHRAE thinks.

04-20-12, 08:58 PM	#20
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	I always thought the idea of more insulation in the roof came from the vented aspect of the roof increasing the surface heat conductivity of the insulation since there is air flow directly over it requiring more insulation while the walls are sheated and essentially have a layer over them. In the winter with the ceiling having the hottest air that supposedly you'd want more insulation there. Not to mention it's easy to load a whole bunch of loose fill cellulose up there. In my case it's about the only place I can add cellulose to my current house without tearing out drywall, which makes it a large and easy retrofit opportunity. As long as all air sealing opportunities aren't missed before loading a pile of treated paper up there, it's about one of the only options for adding R-value for most. In a new house R60 might be more than enough, depends upon the standards for energy use that someone is going after, I'll have to read those sections of my Manual J again and read the factors on heat loss through the attic versus the walls so I can make comments about what ASHRAE thinks.