Zone 3/Central GA 12×32 weekend cabin on 36″ above grade piers
Building Envelope Critique Please/Materials purchased and we’re about to begin:
1) From interior: 1×6 T&G pine fastened directly to 2×6 studs 24″ OC; R-19 fiberglass batts/caulked gaps & seams; 1/2″ plywood sheathing; one layer 1/2″ pink foam board/taped seams; 4×8 exterior panels. Where is best positioning for my WeatherMate Plus wrap?
2) Floor system: 2×10 joists; R-19 batts; two layers of 1/2″ plywood; interior flooring to be reclaimed heart pine planed to 3/4″ glued and cut-nailed to plywood. Considering Building Science article approach to apply 1/2″ pink foam board to underside of joists/tape seams. May WeatherMate Plus wrap be incorporated and between what layer(s)?
3) Roofing from interior: Same T&G as on walls directly to 2×6 rafters 24″ OC; R-19 batts/caulk & sealing; 1/2″ plywood; 2 layers of 1/2″ foam board/taped seams (overkill in zone 3?); purlins and 5V galvanized metal roof. I have excess of WeatherMate Plus wrap – may it be utilized in the roofing plan in lieu of #30 felt? 4 x 12 pitch gable with no penetrations in the roof deck.
The cabin will have a small bathroom with shower/sink/through wall exhaust fan. No cooking will take place indoors.
Please provide ALL pro and con comments and suggestions. This is a fantastic site, along with Building Science and Fine Homebuilding Magazine!. Thanks in advance.
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Replies
Brad,
Q. "Building envelope critique, please."
A. Your walls and ceiling need an interior-side air barrier. Tongue-and-groove boards are notoriously leaky. The best approach is to install a layer of drywall with taped seams before you install your tongue-and-groove boards.
For better floor insulation details, see How to Insulate a Cold Floor.
For better roof insulation details, see How to Build an Insulated Cathedral Ceiling.
Q. "Where is best positioning for my WeatherMate Plus wrap?"
A. See this article: Where Does the Housewrap Go?
Martin: Thank you - a follow-up: Assuming I have 'extra' 1/2" plywood, will that serve the same purpose as the taped-seam drywall approach?
Brad,
Q. "Assuming I have 'extra' 1/2" plywood, will that serve the same purpose as the taped-seam drywall approach?"
A. Yes, but only if you tape the seams of the plywood with a high quality tape that is suitable for use on plywood. For more information on tapes, see Return to the Backyard Tape Test.