Will architectural shingles last longer with an entangled mat underneath them –between the underlayment and the shingle. We will have a conditioned attic and no open ridge vent on top of roof.
The code requires installing an approved material to slow the spread of fire between floors and adjacent vertical and horizontal cavities — here are the allowed materials and required locations.
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Replies
roofing underlayment is designed to be fine directly under shingles.
the matt products you are asking about are intended to be included in wall assemblies.
There are complications with sealing up the roof deck.
conditioning the attic turns the roof into a cathedral ceiling
https://www.finehomebuilding.com/?s=cathedral
https://www.finehomebuilding.com/membership/pdf/7319/021228066.pdf
Is worth a read.
it can be challenging to get the required insulation R value into the roof rafter area.