Window sill or window ledge?


Senior Member
English UK
I have scoured Google and a variety of dictionaries for an unequivocal definition of which of these terms, sill or ledge, refers to the inner or outer part of a window frame support with no success. Entering "sill" in images brings up both interior and exterior views of windows, as does entering "ledge". I know that there is a difference in construction terminology, but which is which? If there are any civil engineers/construction experts out there who know the answer, I would be extremely grateful.


Senior Member
U. S. - English
Tradman said:
Thanks to you both. That now makes three of us of the same opinion. It must be the rest of the world that's confused.
I'm not confused. I had the same answer as you all before I even opened your original post.;)


Senior Member
ledge = A horizontal projection forming a narrow shelf on a wall.
However, windowsill and window ledge are showed as being synonyms on
1. The interior or exterior ledge that runs along the bottom of a window.
I always think of the window ledge as being on the outside of the building... that makes 3 4 of us!
My late father was an architect - his drawings had sills on the outside of the buildings.
Both Chambers and the Oxford Concise dictionaries just say that a sill is at the bottom of a door or window and do not mention whither it points.
Collins says "inside a room".
Chambers has the single word windowsill as inside or outside, (and it gives windowsill as the definition of window ledge) the OCD has it as two words window sill and doesn't mention in or out (and it too says window sill is the definition of window ledge).

I delight in being the odd one out!
English English (from England)
My mum would say window sill is 'posh', whereas window ledge is 'common'!

Actually Chambers gives the definition of window ledge as 'a windowsill', but windowsill is defined as 'an interior or exterior ledge running along the bottom of a window.' Thus I'd say sill is correct, ledge isn't.
English U.S.
Hi, new member. I was wrestling with this, checked a few sources and here are my thoughts from a combination of observation and research.

Window sill is the most commonly used term for the interior. It is a ledge, yes, but while one might say "Oh, you put your drink on the ledge by the window," window ledge is rarely used for the interior.

The outer piece can be called either, though I think window ledge is better, but with many prehung windows the interior piece and the exterior piece appear to be all one. I would imagine this is in part why people use the word sill. But! If the exterior part is stone or brick then the word ledge is a better usage.

That said, the O.E.D. simply defines sill as the horizontal bottom part of a window opening, made of either wood or stone.
English, England
As far as I know, window ledge is not a standard architectural term. The internal ledge is commonly called a sill, whether it be timber or tiles or some other material. It is not normally an integral part of the window. The outer member is also called a sill and is commonly "weathered", i.e. it has an upper surface which slopes away to shed water. It is usually an integral part of the window.
English U.S.
Yes, the modern pre-hung window has the bottom part as an integral part of the assembled window. (They didn't make them like that in your day, Giordano. Good to know hell has the internet, you heretic.) But what if that window is set in a wall that is so thick that the weathered outer sill does not reach the outer face of the wall, let alone project from it slightly as is the custom in modern house construction? What would you call the stone, brick, or even metal shelf that extends beyond the pre-hung window? What would you call the piece of granite I'm looking at that sits upon the top of the brick facing of a thick apartment building wall and extends well beyond the sill but is most definitely part of the "window opening," i. e. the hole in the wall awaiting a window? I say window ledge.

Being a language person and not an architect, I suggest that it is from such forms of construction that the socially constructed distinction originates. Yes, the interior "sill" is not in fact part of the window at all and therefore more of a ledge than a sill, but if everyone calls it a sill and it's made to look aesthetically as if it were, and maybe it once was, before pre-hung windows--(Do you still remember that far back? Do you remember how you died?)--then it's a sill just the same.

But trying to get people to stop calling it a sill would be like trying to get people to stop saying "cement" sidewalk, when it is in fact concrete.

That's how language changes.

English, England
Greetings Barnaby,
Well of course, we don't have any windows down here, but I am reliably informed that in modern cavity wall construction, the lower part of the window sits on a weathered brick sill which does in fact project beyond the face of the wall.
By the way, I'm with you all the way on cement buildings and footpaths. A lot of people who refer to them as such end up as my neighbours in a special walled off section.


Occasional Moderator
English-Ireland (top end)
Sill - A horizontal piece forming the bottom frame of a window or door opening.

sill - The framing that forms the lower side of a window or door. A lug sill extends beyond the width of a window, where a slip sill is only as wide as the window.

Similar definitions in numerous alternative glossaries of architectural terms.

It appears that colloquial usage may vary considerably from the architectural definitions.