Sill

The sill sheds water away from the opening. It must slope outward and seal tightly to the wall. On a window it forms the base of the frame. On a door it is the threshold you step across.

Sill details matter more than most buyers expect. A weak sill detail can let water in. For doors, ask how low the track or threshold sits and how it drains. Good flashing under the sill is just as important. Compare door types in our sliding and lift-slide doors pillar. Ask for a sample cross section to see how water leaves the track.