Rigid foam and rafter tails
Robert Brown| Posted inGBA Pro Helpon
The attic is conditioned space due to foam spray on the underside of the roof deck. Foam also fills the void between top of wall and roof deck. So, when I install my exterior rigid foam should I stop at the top of the wall or cut out for rafter tails and continue the foam to the bottom of the roof deck.
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Replies
Robert,
Either way will work. If you take the latter approach, the blocking between your rafters or trusses will have a higher R-value, and the rate of heat loss will be reduced.