How To Repair Rotted Window Sills =link= Direct

If the damage is limited to a small area, apply a wood filler or epoxy-based repair compound to the affected area. Use a putty knife to spread the filler or compound evenly, feathering it out towards the edges to create a smooth transition. Allow the filler or compound to dry according to the manufacturer's instructions. If necessary, apply multiple coats, allowing each coat to dry before applying the next.

Shape the repair to shed water. The sill must slope away from the house, about 5 degrees. Any backward tilt is a suicide pact. how to repair rotted window sills