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Insulating small area of roof / ceiling - IECC exemption?

Jay

Sawhorse
Joined
Apr 8, 2018
Messages
72
Location
NJ, USA
Hello....not doing too much commercial work I am looking for guidance on a small project. Commercial office building has a small 10 x 9 greenhouse type wall/roof assembly that was built in the mid-80's. Owner wants to replace with wood frame assembly with solid roof and new window wall. I have a question about insulation...

The area for new roof framing works best with a 2 x 6 rafter in order to maintain the wall height for windows. Ok with the rafter span. Looking to avoid spray foam insulation if possible. I see that per IECC we are required to have R-38. Can anyone please steer me in the right direction as to where I might find an exemption in the current energy code for such a small area? Not sure if C503.3 building envelope for existing buildings helps without me analyzing the entire building? I am going from full fenestration to solid roof. Common sense we will be better off. Thanks!
 
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classicT

Sawhorse
Joined
Aug 2, 2017
Messages
1,876
Location
Washington State
Not sure that you will find an exception....

But if it were me, I would go with the U-factor method. Insulate the void with batt, and add some continuous insulation on the top of the deck. Would mean a TPO roof, but I would be that is doable.

Otherwise, 2x10 rafters are in your future.
 
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Jay

Sawhorse
Joined
Apr 8, 2018
Messages
72
Location
NJ, USA
Thanks for the replies. I emailed the Building Inspector and will see what he has to say.
 
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