Deck Attachment for a Superinsulated House

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Crafting a strong structural connection to a high-performance house.

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Since last fall, JLC has been following a high-performance custom home project on Peaks Island, in the Portland, Maine, harbor. The distinctive home is designed for compliance with the strict Passive House standard for energy performance, and it also sports some unique architectural elements—such as the two-story window-wall space topped with unusual roof geometry we described in the February 2017 issue (see: "Roof Framing Challenge," 3/17).

Designed by Portland architects Kaplan and Thompson, the house has posed a long list of technical challenges to the construction crew from building contractor Thompson Johnson Woodworks. Among the tricky situations is an outdoor wood deck, which will ultimately serve as a bridge from the main house to an accessory guest house a few feet away. Attaching the deck to the superinsulated house with a strong structural connection, while maintaining the home's air control and vapor control layers, has been a complex puzzle for lead carpenter Mark Pollard and his crew. The solution was to mount the deck to the house with Maine Deck Bracket hardware, wrapping the VaproShield air barrier behind a triple 2x8 structural deck ledger outboard of the hangers and taping the membrane to the air barrier for the wall above the deck and the air barrier for the elevated floor system.

In the gap created by the hangers, the crew applied 3 inches of rigid foam insulation, drilling holes in the foam for the bracket mounting bolts and sealing any gaps with gun foam. The aluminum brackets still create a thermal bypass from the deck ledger to the LVL band joists where the brackets mount to the house, says Pollard—a compromise the team will have to live with.