Sills that have lost their "fall" (outward slope) or have blocked drip grooves allow standing water to sit on the timber.
In colder climates, moisture from the inside can condense on sash frames and drip onto the sill. wooden window sill repair
A rotting or cracked wooden window sill is more than an eyesore. It’s a gateway for water infiltration, insect infestation, and heat loss. The good news? Most wooden sills can be fully repaired in a weekend for a fraction of the cost of a full window replacement. Sills that have lost their "fall" (outward slope)