“Thermoply” applications ?
“Thermo-ply” is an interesting material, less than 1/8″ thick and sold as a structural sheathing that can replace OSB as an air barrier etc. I’m considering it as my main air barrier in my thick walls, as a web in Larsen like trusses, under my roof trusses both to support the cellulose above and as the air barrier over a service cavity’ and as “tie” plates and around window & door openings for my double wall. My walls will have the primary air barrier on the outer face of an inner 2×4 wall with 2×4 top and bottom plates and an outer wall made of Larsen like trusses for studs. The inner wall is “structural” and sits on the foundation while the outer wall is “proud” of the foundation and is cantilevered over a conventional masonry brick exterior of the foundation. The “Larsen like trusses” consist of 2 ea. 2x2s spaced 3 1/2 ” apart and glued & stapled , on one side, to a strip of Thermoply that is 7″ wide the space between the 2×2’s is filled with a 1 1/2″ x 3 1/2″ strip of mineral wool. The two walls are tied to each other by strips of Thermoply at their tops and bottoms, for the inner wall this is an extra top and bottom plate, however for the outer wall it is the only top and bottom plate. I plan on using a 24″ OC staggered layout. The construction sequence is, one segment at a time: frame the inner wall, add the Thermoply sheathing layer, tape the seams, cut the openings add the top and bottom tie plates and “rims” around the openings, tape the sheathing to the tie plates and “rims”, construct the outer wall nailing the pre-built insulated trusses to the tie plates, add the outer 7″ of mineral wool between the truss-studs. The wall segments are erected sequentially with caulking and sealing to the previously erected segments. Once the wall, or any of it’s segments is vertical additional nailing/stapling of the outer wall trusses to the Thermoply can be done if needed. Once erected the exteror UN-SHEATHED mineral wool filled walls will be covered by a moisture permeable “housewrap” then DC14 drainage mat XPS, then either “Hardieboard” or Ambrico EZ wall panels and attached thin brick. What do YOU think?
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