Sill
Definition and meaning of Sill in real estate.
A sill is the lowest horizontal member at the bottom of a window or door frame, designed to channel water away from the opening. It is sloped outward to ensure rain runs off and does not pool or seep into the wall structure.
In more detail
Window sills are visible on both the interior and exterior of a home, while door sills are commonly referred to as thresholds. In framing, the rough sill is the horizontal wood piece that supports the bottom of the window frame itself. Sills are highly vulnerable to rot because they are exposed to moisture, especially if paint peels or caulking fails.
During a home inspection, inspectors closely examine sills for soft wood, which indicates water damage that must be repaired to prevent structural issues.
Key facts
| Category | Property Types & Construction |
|---|---|
| Also known as | Threshold (for doors), rough sill (framing) |
| Common Issue | Wood rot due to pooling water or failed caulking |
| Required slope | Angled outward to shed water |
A home inspector uses a moisture meter on the exterior window sill of a bedroom and discovers elevated moisture levels, signaling a leak in the caulking.
Frequently asked questions
What is the difference between a window sill and a window stool?
The window sill is the structural bottom of the frame that slopes outward, while the stool is the flat, shelf-like piece on the inside of the room.
How do you repair a rotting wood window sill?
Small areas of rot can be carved out and filled with epoxy wood filler, but severe rot requires replacing the entire sill board.