Air sealing plumbing/skylight penetrations in insulated over-roof?
Looking at doing a chainsaw reno on a 1942 1-1/2-storey gable house. Region 4 Coastal.
Proposed stack-up (bottom-to-top) on the roof is:
– existing drywall
– existing 6-mil poly
– existing R-28 fibreglas batts over the inhabited part (poorly installed) with no ventilation chutes, no eaves vents
– existing 1×6 skip sheathing (from original cedar shake roof)
– existing OSB roof sheathing
– new BlueSkin VP160 vapour-permeable peel-and-stick
– new 8″ of Roxul comfortboard IS, staggered
– new 2×4 strapping laid on side, aligned with rafters
– new plywood sheathing
– new tar paper
– new asphalt shingles or metal roof
Given the ventilation channel between the Roxul and the shingle deck, there would be air leakage around the roof penetrations if they were sealed/flashed to the shingle roof deck in the traditional way.
How should we air seal the roof penetrations down at the BlueSkin layer yet still provide flashing up at the shingle plane?
– 4″ plumbing stack?
– brick chimney?
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