What Is a Sill in Construction?

Sills are a vital part of any construction or remodeling project that includes windows. Sills add support, as well as decorative and protective elements to windows.

Identification

A sill refers to the bottom, horizontal part of a window frame. It may also refer to any decorative elements at the bottom of the window opening. At times it is used to refer to the bottom of a door frame, though this is more commonly called a threshold.

Function

In addition to providing the necessary support for the window frame, a sill may also be used as a decorative element. The materials used, the distance it protrudes into the room and its shape can dramatically change the look of the window and the room.

Exterior Sills

An exterior window sill channels water away from the window and the building. Water can rot wood and cause brick to crumble, so a sill can protect a building from water's damaging effects.

Materials

Sills are usually constructed out of the same material as the rest of the window frame, which may be wood, metal or vinyl.

Features

In brick construction, an additional brick sill may be added to the exterior of the building for design purposes and to help keep water away from the window. Interior decorative sills are usually made from wood, wallboard, metal or stone.

References

• Window Sill Construction