How do I improve R Value and change to metal on my roof?
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I have an older Pan-Abode home that has cathderal ceilings with minimal roof R Value. I would like to increase the R Value and lay metal roof over shingles. Does anyone have insight on the best way to do this?
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Replies
Laurence,
Before reading your question, I had never heard of Pan-Abode homes. (For GBA readers who are curious, Pan-Abode is the name of a Canadian company that sells kits for building log homes -- specifically, log homes made from milled logs.)
To improve the R-value of your roof assembly, you can add insulation on the interior and then install a new ceiling, or you can add insulation on top of your roof deck and then add new roofing.
Since you are planning to add new roofing, it sounds like it would be easiest to install rigid foam insulation on top of the existing roof sheathing, followed by a new layer of roof sheathing (or strapping) and new metal roofing. Another option is to install nailbase (a sandwich of rigid foam and OSB, like a SIP with OSB on only one side).