The cape-style post-and-beam
house was five years old when
I first saw it. The builder who
had originally built the shell had
opened up one wall to build an addition.
What he found under the rigid
foam insulation on the exterior was
severe rot in the pine board sheathing.
The pattern of rot closely followed
the post-and-beam framing.
The frame was built with 8x8
hemlock timbers, and the spaces
between the timbers were filled in
with 2x4 framing. The 2x4 infill
walls were insulated with R-11 fiberglass
and covered with 4-mil poly
and drywall on the inside (see illustration).
The exterior was sheathed
with 1x8 diagonal pine boards, covered
by 1 inch Styrofoam rigid insulation.
The siding was backprimed