A question of Window Cills

[cabiri.tech]

Now I know this is a stupid question but I'm trying to get my head around measuring up for windows for a timber frame opening.

When you're looking at the opening from the exterior does the top of the cill (reconstituted stone) sit level with the bottom of the timber frame window opening or is it the bottom of the cill that sits level with it.

I need to work out if the window opening will be the final size to give the glaziers or if I have to take the height of it and deduct the height of the stone cill.

I've had two different thoughts on it so far so any help in what is normal practice would be much appreciated.

Thank you.

[bigcat]

I'll let someone else answer this one: just glad to see its not a cilly question.

NT

[John Rumm]

IME, the frame sits on the cill (or at least level with its top surface)...

[jacob]

I'd ask the glaziers to measure for themselves

[biff]

Measure the minimum distance from top of masonry cill to bottom of lintel. This is the size of the actual opening in the wall. Deduct a few mm to allow for irregularities. Order the height of the wooden window accordingly.

[fred]

In article , [e-mail] writes

In these parts (scotland), this sort of window is specified by the 'stone opening' size, the wooden cill will rest on the stone cill but top, bottom & sides will overlap with the stonework but sit inside. In this case there is no need to deduct from sizes. Typically 10-15mm of the frame will be visible at sides & top when the window is fitted.

Quoting the stone opening size when ordering puts all the responsibility on the manufacturing joiner to get the sizes right.

Glazier?, misnomer or a bit of a funny setup.