If you have any comments or corrections on this article, please email us and we can publish your comments. When a rainy day is followed by a sunny day, the exterior side of each piece of siding will be dry, while the interior side will be wet. Because of plywood, that's why. Polyurethane foam has the added benefit of sealing air leaks, but you shouldn’t consider installing it directly against the back of the siding. By reducing the number of studs to three or two, builders can fit insulation into these cold spots. Probably because tape measures have red marks every 16 inches, and we are all accustomed to framing at 16 inches on center. Some people recommend omitting most of the wood wall sheathing in favor of exterior rigid foam, using plywood or OSB on the corners and in shear wall locations. A less conservative approach is to use 3⁄4-in. Originally published by: Fine Homebuilding — May 17, 2016. And when I read about Optimum Value Engineering, I mistrusted it. Once they are in position, rectangles of rigid foam can be inserted (cut-and-cobble style) against the spacers in each stud bay. There are two possible ways to approach this situation. Parting Shots: Let it Snow, Let it Snow, Let it Snow. From a comfort standpoint here in climate zone 4, we think this will be a good tradeoff to using 2×6 walls that have a moderately higher R value but a bit more thermal bridging. Starting from bottom, first course of SOLITEX MENTO PLUS is rolled out across trusses, followed by 4’ long 2x4 vertical battens. We can frame and sheathe them flat on the ground, build overhangs and soffits, and even install siding and … For studs 16 in. The interior 2x4 framing of the double stud wall was added inboard of the 2x6 exterior framing. Making spray foam work At 475 High Performance Building Supply, we’re always challenging builders to build to best practices. Drainable housewraps are available from several manufacturers and have bumpy, crinkled, stamped, or channeled textures that maintain an air gap of at least 1 mm. Cut the felt as long as the stud bays, but about 2 in. on center, 3⁄4-in. MENTO PLUS has 3 month UV exposure rating, so final roof can wait. o.c. It cost me six bucks back in 2001 and appears to be about 40 bucks now at amazon. It’s enclosure-first projects like these that will get us closer to global carbon reduction goals. They also cover corners, headers, and wood sheathing panels. At .56 ACH 50, this project achieves Passive House airtightness with some of the most sustainable building components now available in North America. It was instead of INTELLO PLUS across all wall and roof interiors, and taped with TESCON VANA. Why not 13, 14, 15, or 17? These vertical spacers need to be tacked to the framing, up against the siding. Like INTELLO PLUS, DB+ is resilient enough for direct dense-packing, but experience and equipment can make the difference for a perfect installation. XPS or polyiso should suffice for fiberglass or mineral-wool batts. Pro Clima DB+, our reinforced paper-based airtight smart vapor retarder, was a perfect fit for this super sustainable, all-wood project. The formaldehyde-based glues often found in sheathings like plywood or OSB can additionally inhibit great indoor air quality. In the end, we can’t solar panel our way out of the climate crisis. Builders traditionally do NOT like advanced framing, for many reasons: All of these responses have at least a hint of truth to them, but they are also easily solved non-obstacles (except maybe the 'hating hippies' part, which sounds like a personal issue). But the felt has a rough texture and will be wrinkly enough to keep air between the felt and siding, even when compressed by the spray foam.