Building a Simple Passive House, Images 1-8

eeping an eye on the thermal and air boundary during construction is key.

An excavated bed filled with crushed stone served as a base for the stemwall foundation, which was stepped down at its upper edge so that the exterior foam insulation wrapping the frame would cover the edge of the mudsill, eliminating a potential thermal bypass.

A vertical strip of polyiso board around the inside of the stem wall minimizes heat loss at the slab edge.

For air-sealing the frame to the slab, the mudsills were bolted in place in a bed of roofing cement.

The stone base inside the stem wall was leveled and compacted, then covered with 6-mil poly and 4-inch XPS insulation.

A layer of 3-inch foam was laid over the first layer.

Joints were staggered and all gaps in both layers filled with spray foam.

A second layer of poly and steel reinforcing followed.

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