Building a High-Performance Shell, Images 1-10

Advance framing and exterior foam are the ingredients for this high-performance shell.

In an advanced frame, headers are minimized in favor of insulation cavities. All framing is vertically aligned and point loads are distributed directly through to the foundation. In this sloped ceiling section, squash blocks carry the rafters’ load path over the second-floor rim joist.

Where interior partitions intersect exterior walls, horizontal ladder blocking will secure the end stud, keeping the wall bay fully open and accessible for insulation.

Structural headers are packed with foam board to create a thermal break.

Openings in nonbearing walls are minimally framed, with single-member headers installed on the flat. The 1/2-inch plywood lining the rough opening extends out to cap the edge of the 4-inch-thick foam sheathing.

For the 24-foot lengths required to frame the main roof, the author used LSL (laminated strand lumber) rafters and collar ties in place of oldgrowth dimensional lumber.

The floors are framed with 14-inch I-joists on 2-foot centers. TimberLok structural screws replace metal ties for faster, code-approved rafter hold-downs.

Intermittent vertical 4-by-10- foot sheets of 1/2-inch CDX plywood applied directly to the frame brace it against wind racking.

Hold-down rods — required with intermittent bracing — are installed at building corners and at regular intervals around the perimeter. They’re anchored in the foundation and continue up the walls through the topmost wall plate.

Anchor in the wall plate

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