Ask three people what the flat bit under a window is called and you might get three answers: window ledge, window sill, window board. They sound like the same thing, and in casual chat they often are, but there are real distinctions worth knowing, especially if you are buying, fitting or repairing. Here is the plain version.
A window ledge is the flat surface at the bottom of a window opening that sticks out a little, giving you somewhere to rest things. In everyday speech, "window ledge" is the catch-all term people use for the shelf-like part under a window, whether it is inside or outside.
Strictly speaking, ledge is the informal word, while sill and board are the more precise terms builders and window fitters use. So when someone says window ledge, they usually mean either the sill (outside) or the board (inside), depending on which one they are pointing at. That overlap is the root of all the confusion.
A window sill is the part at the bottom of the window on the outside. Its main job is not decoration but drainage. The external sill slopes slightly away from the window and often has a drip groove underneath, so rainwater runs off and drips clear of the wall instead of tracking back into the brickwork below.
External sills take a battering from the weather, so they are made of hard-wearing materials: stone or concrete on older homes, and often a uPVC or aluminium sill built into a modern replacement window. A sound sill is important, because a damaged or badly sloped one lets water sit and eventually causes damp and staining below the window.
Because the sill works so closely with the window frame, it usually gets renewed as part of a new window install. When we fit replacement uPVC windows, the external sill is part of the job, set up to shed water properly.
A window board is the flat shelf on the inside, sitting on top of the internal wall below the window. This is the bit you put plants, ornaments or the cat on. Traditionally window boards were timber, and in period homes you still find lovely deep timber boards. In modern homes they are often uPVC, MDF or a laminated board that matches the window.
The internal window board is more about looks and usefulness than weatherproofing, since it sits indoors. It gives a neat finish where the wall meets the window and covers the join. Its depth depends on the thickness of the wall, so older homes with thick walls often have generous, deep boards.
To keep it simple:
So a "window ledge" outside is really the sill, and a "window ledge" inside is really the board. Use ledge in casual chat, and sill or board when you want to be precise.
It is not just pedantry. Knowing which is which helps when you are:
Damp, staining or crumbling below a window is a classic sign the external sill or the seal around it has failed and is letting water in. That is worth sorting sooner rather than later, before it spreads into the wall. Our window and door repair team across York can check the sill, the seals and the surrounding pointing and put it right.
A quick word on looking after each:
If your windows are older and the sills are tired, it can be a sign the whole window is due for renewal rather than just patching. Modern replacement windows come with matched sills and boards as standard. For a period property where you want to keep the character, our casement window range offers traditional looks with modern sills that shed water properly.
Costs depend on the material, the size and whether it is a standalone repair or part of a new window. As a rough UK guide, replacing an internal window board or repairing an external sill is usually a modest job running from a low figure into a few hundred pounds, while renewing sills as part of full window replacement is folded into the window price. Treat any online figure as a ballpark only. For an accurate number, get it looked at. You can request a free quote and we will give you an honest price.
Loosely, yes, but strictly no. Window ledge is the informal catch-all term. The window sill is specifically the external part that sheds rainwater, while the internal shelf is properly called the window board.
The sill is outside and its job is drainage, sloping to run rainwater clear of the wall. The board is inside and its job is a neat finish and somewhere to put things. Sill for weather, board for looks.
Usually because the sill or the seal around it has failed and is letting water sit rather than run off. Left alone it can spread damp into the wall below, so it is worth checking the sill, seals and pointing and repairing them.
Often yes. If the window itself is sound, the internal board can usually be swapped on its own for a fresh finish. If the external sill or the window is failing too, it may be better to renew them together.
Window ledge is the everyday word, but the precise terms are sill for the weather-shedding part outside and board for the neat shelf inside. Knowing the difference helps when ordering, reporting a problem or chasing down damp, which nearly always starts at the external sill. Want to see the window styles and finishes in full? Download our latest brochure, or book a free quote and we will come and measure up.