High Priorities.

The structure of the existing house wouldn't support our new design, but we could reuse the foundation, which allowed us to avoid excavation and capture the embodied energy of the existing concrete. The poured concrete foundation walls and footings were in good shape, but the existing basement slab was removed to allow for new interior footings, subslab insulation, and vapor and air barriers. The north side of the house was extended with a 3-ft. cantilever, but otherwise held to the existing foundation plan and deck perimeter. To achieve an air infiltration rate of only 0.53 ACH50, the house has closed-cell spray foam under the basement slab and on the basement walls, open-cell spray foam at the rim joists, and continuous taped Zip System sheathing on the walls and roof. [Extracted from the article]