Does untreated OSB with peel-and-stick taped joints qualify as a Water-Resistant Barrier?
We have untreated OSB on the walls, with the intention to tape all joints, corners, window bucks, joint to roof sheathing, etc.
This house is in the Northeast, and our wall section is siding on vertical strapping (rainscreen) on 3" shiplap Poly-Iso (R21) insulation on OSB on 2x6s at 24" OC with cellulose fill (say R17, for a total of ~R38-40). The roof section is metal on cross purlins on 2x4s on 2 sheets of 2" XPS (R20) on ZIP sheathing on 12" TJIs at 24" OC with cellulose fill (say R37, for a total of ~R57-60). The basement with walkout has 4" XPS on the exterior walls for now, and when finished we'll add another R10-15 cellulose or XPS. Under the slab is 2" XPS.
Is there a dew point potential inside the wall and roof cavities? We've got more than the 1/3 R-value rule of thumb for interior vs exterior insulation. The mechanicals are high-efficiency propane furnace, HRV, A/C (future if needed), and a masonry heater. The house is a simple gable, with a footprint of 1300 sf on 2 levels plus a full basement and unfinished attic (for future use), for a family of 3-5. There is no swimming pool or green house indoors, though there will be some plants and the masonry heater with wood storage. Appliances & bathrooms have typical mechanical vents to the exterior. Does any know of resources for on-line dew point analysis?
Posted Fri, 01/08/2010 - 17:05
Edited Sat, 01/09/2010 - 07:31
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