At all doorway entries. Tap sub floor, probe when possible & listen for soft or delaminating sheathing. At door entries on decks or concrete stoops where door threshold is within inches of the surface. Water and snow can back up and seep under the threshold. Check toe kick, sub floor, and other trims. Lack of drip caps over wood trim, windows or doors. These areas are susceptible to water infiltration.
Vertical trim that runs to the ground or concrete where the capillaries of the wood can absorb the water. This is referred to as wicking and is very common at garage doors and entry doors. Any siding or trim that is close to or touching the ground or concrete. This can cause damage to wood siding as well as to the sheathing and framing in the wall.
Termites may create an undetectable path as well. Columns or post resting on concrete without a pad, can soak water into the capillaries, and may rot. Roof sheathing due to; ice damming, leaves clogging and where there is no drip edge at the gutters. Tongue and groove porch flooring at the end grain. Closed in porches with the flooring is still exposed to the outside. In the attic, at the gable ends and at the bottom near the soffits look for water stains or rotting at the sheathing from the end grain.
In the attic sheathing at plumbing vents, around chimneys, skylights and other roof penetrations. Wood exposed to the south side or a lot of direct sun. Any wood exposed to continuous dampness. Damp or wet crawl spaces can promote fungus, mildew and lead to rot. Any wood trim especially at the end grains. Exterior trims which are not back-primed or sealed at the end grain.
Any plywood used outside for paneling or trim that is not marine grade, back primed or sealed at the end grains. Foundation sill plates which are untreated Floor sheathing at toilet drain and other plumbing floor penetrations. Wooden window sills. Windows in shower stalls All tub and shower wall penetration, such as spigot and mixer valves. Any failing tile grout at floors, shower pans and walls. Floor adjacent to the tub or shower.
Any exterior trim or J-Channel which sticks out past the siding, window, doors, etc. that could allow water infiltration. Where any exterior caulking is missing, failing, or blown out. Where any paint is visibly peeling of cracking. On the roof near all chimneys, plumbing vents around the perimeter, skylights and ventilation.