Most of the rim joist
wetness and mold are caused by the moisture from the uncovered crawl space dirt floor migrating through the rim joists
' fiberglass insulation, which is lacking a plastic vapor retarder.
The basement was constructed with insulated concrete forms (ICFs) and the rim joist
was insulated on the outside with 5.1 cm (2 in) thick polystyrene insulation (R-10), to eliminate condensation and consequently reduce mold and mildew.
Decks are also problem areas if the rim joist
wasn't well flashed.
Platform framing consists of a rim joist
box that runs around the outside of a structure inside of which the joists are hung.
(A) A rim joist
is the piece of lumber that locks the floor joists together and helps bear the weight of the walls above it.
To increase the strength of these areas, the rim joist
can be doubled, or bridging or blocking can be added between the rim joist
and the first interior joist.
Better yet are through-bolts if you have access to the rim joist
from the basement.
If the front rim joist
(the frame member that supports the front end of the decking and holds deck-front joist hangers) is shot, you may be able to sister a new length of PT outside of it and fasten new hangers between the old ones by running long bolts through thickness of both old and new wood.
When you're hanging drywall or plywood or even a rim joist
, mark the framing locations and tack a few fasteners in the material before hoisting it.
The rim joist
is the solid blocking around the outside of the building, but you also need blocking under interior bearing walls.
The cut ends of beams and joists are boxed with a rim joist