Exterior insulation prevents condensation

Rim joists are difficult to insulate well. When rim joists are insulated on the interior with fiberglass batts, the insulation does little to slow the migration of humid air from the warm interior to the cold rim joist. Over time, such condensation can lead to rot.

Insetting the rim joist by 1½ in. or 2 in. carries no structural penalty; in its new location, the rim joist still transfers the wall load to the foundation. In all but the coldest climates, such exterior insulation will keep the rim joist warm enough to prevent condensation.

The whole point of advanced framing, also known as optimum value engineering (OVE), is to frame a house so that it meets its structural requirements without wasting material. A welcome corollary is that the same house will have more room for insulation inside the walls and will therefore be more energy efficient than a conventionally framed house. Minor downsides, for example, attaching trim in areas with less structural lumber, and wider spacing of siding fasteners, are easily overcome.

Frame walls with 2x6s @ 24-in. o.c.

Fewer studs can save a lot of wood and increase the energy performance of a house by making more room for insulation.

Stack the framing

Aligning framing members between floors transfers loads efficiently. This means that you can omit the double top plate in favor of a single one. It also facilitates a better-quality job when attaching the plywood or OSB sheathing that spans these transitions.

Place doors and windows on the grid

Moving door and window openings so that they line up on the 2-foot grid reduces waste and, again, leaves more room for insulation.

Use less wood in the corners

Exterior corners can do well with fewer studs and more insulation in them. The same…