EcoCor, Inc.

EcoCor's wall system uses wood I-joists applied to the outside face of an OSB-sheathed 2x4 stud wall, to form a cavity for dense-pack cellulose insulation. Says builder Chris Corson: "It's like wrapping the house in a puffy jacket of cellulose."

Full-height wood I-joists are applied to the gable end walls before the roof is sheathed with breathable fabric and strapped to create an air space under a plywood nail base for asphalt roofing. (Some houses receive steel roofing instead of plywood and asphalt).

Wood I-joists are fastened through sheathing to the inner stud wall through tape-sealed OSB sheathing using GRK RSS structural screws.

Window openings are framed out to the depth of the wood I-joists using engineered rim-board material. In this example, windows will be set flush with the outer face of the strapped wall. But in other cases, windows may be set at the center of the wall.

After the I-joists are affixed outboard of the stud wall, a drainage plane of Solitex Mento Plus "sarking membrane" is stapled onto the outer edge of the I-joists. This waterproof but breathable fabric will shed incidental water that may get behind the wall siding, and will allow the wall to dry to the outside.

Carpenter Rich Perry staples Solitex Mento Plus breathable "sarking membrane" to the face of a wood I-joist. OSB Joints in the underlying 2x4 stud wall have already been sealed with Tescon Vana vapor-permeable air-sealing tape. The cavity formed by the Mento Plus will be filled with dense-pack cellulose.

This view of a house under construction by Belfast, Maine, builder EcoCor shows one wall covered with Mento Plus fabric and criss-cross strapping, while the other wall awaits the application of the breathable drainage-plane fabric.

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