By LiamK
I have a question on recommended roofing materials for the flat roof, and their sequence. The roof is flat and is 32 squares (including shop and carport), in the rainy Pacific Northwest. Does the following sequence make sense? Or is the sequence wrong? Can I cut anything, to save money? Anything I should add, like Tyvek/Typar — if so, where?? From the top down:
* membrane (probably PVC; or torchdown)
* #30 roofing felt
* peel-stick water-and-ice barrier [GAF or Grace or ??]
* [possibly 1″ XPS rigid foam insulation if I can afford it, to insulate and smooth any rough old deck; R5]
* old tongue-and-groove wood decking (on drip-edge replaced 4′ in, and as needed)
* 2″ airspace
* 5.5″ Roxul rock-wool insulation R22 [more mold-resistant than fiberglass]
* drywall ceiling (probably paperless-drywall, to limit mold; DensArmor or ??)
* latex paint (Kilz II primer)
It’s a very flat roof, a 1:16 slope (too flat) that leaked on and off for years, so there was a very serious mold problem (requiring a complete gut inside of all drywall and trim). I need to tear off layers of old build-up (hot-tar) roofing, and repair parts of the deck, and fix some joists/rafters that are rotted for 3′ on the drip-edge. I’ve read lots of debates about torchdown vs PVC membrane. I’m currently leaning towards PVC, despite the higher cost, as its safer for me to install myself (no flame), and white is better in summer (I’ve no A/C). I worry about condensation if I use PVC, though I’ll add at least two 2-way vents (kitchen and bath) and the soffits have vents.
I really appreciate any sound advice, especially from those who’ve been around long enough to see fads come-and-go. Many thanks in advance!
Source: DoItYourself.com




