Does this plan for a vented over-roof make sense?
Hi all, first time asking a question but I’ve found this Q&A very helpful in the past. Thanks in advance for your help.
I’m planning to add a vented over-roof to my zone 6 northern NY house. It has three roof sections: two cathedral and one with an attic. I’ll be dense packing the cathedral ceilings with cellulose and spray foaming the attic before over-roofing, making all three roofs hot and roughly R-25+ before the over-roof. Here’s the thinking on the vented over-roof layers, from bottom up:
2) Air barrier membrane
3) 5.5” of XPS foam with staggered joints–top layer taped at seams
4) 1” furring strips running vertically (spacing for ventilation)
5) Plywood sheathing
6) Ice & water shield / 30lb paper (Grace in two bad valleys and 3ft from all eaves and edges)
7) Asphalt shingles
Does this make sense? Anything I’m missing? The thought is to frame around the roof with two by sixes to give us something to nail new flashing to and make the insulation easier to install and more solid, and the new fascia would overlap the old fascia with an inch of space to act as a soffit vent. All ridges would be vented as well.
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