Launch Slideshow

EcoCor, Inc.

EcoCor, Inc.

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    Photo by George Reefer

    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."

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    Photo by Ted Cushman

    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).

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

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    Photo by Ted Cushman

    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.

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    Photo by George Reefer

    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.

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    Photo by George Reefer

    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.

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    Photo by George Reefer

    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.

Launch Slideshow

GO-Logic, Inc

GO-Logic, Inc

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    Ted Cushman

    Carpenters apply beads of acrylic sealant to SIPs and stick framing to create an air seal, prior to installing a short section of SIP above a door opening.

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    Ted Cushman

    The short section of SIP is a hair too long for the opening because of a small inaccuracy in placing the adjacent panels.

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    Carpenters confirm that the small SIP section is too long for the opening.

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    A carpenter trims back the OSB skin of the short panel section in order to allow the piece to fit into place.

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    Carpenters fit the modified SIP piece into place after trimming to fit.

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    Carpenters attach the panel section to the stud wall frame using long hardened screws supplied by R-Control.

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    Ted Cushman

    Panel splines are nailed into place at the panel joint using 8-penny nails.

The little mid-coast Maine town of Belfast is unusual in a variety of ways, including one that you wouldn't necessarily expect: Belfast is home to not one, but two high-performance builders who are leaders in superinsulated Passive House construction. Each builder is crafting houses that far surpass the performance of the typical Maine home, but they're pursuing their goals with different business models and different technical approaches.

GO•Logic, Inc., a partnership between architect Matt O'Malia and builder Alan Gibson, is wrapping up construction on a 36-unit cohousing project in Belfast, involving 12 separate buildings constructed using a combination of stick framing and structural insulated panels. EcoCor, Inc., run by builder Chris Corson, is building single-family Passive House homes on scattered sites in and around Belfast, and is ramping up an operation to panelize the system Corson developed (which incorporates wood I-joists into the wall assembly and relies extensively on advanced fabrics and air-sealing tapes).

EcoCor's and GO•Logic's advanced wall systems are featured in a December feature article in the Journal of Light Construction, including details of the integration between the walls and their respective roof and foundation systems (the story also includes two other solutions to the above-code envelope puzzle by architect-builder teams in Connecticut and Vermont). Here's an on-the-job preview of the two Maine solutions.