Wall thickness and sill dimension?

[gcol]

I'm just redesigning an emergency escape ladder that fits through a window opening and need a couple of dimensions.

What would you say would be the most typical thickness of a house wall? I'm after a dimension from the outside face of the brick to the internal face of the plaster (I suppose this would be 2 brick depth, plus cavity, plus plaster).
Also, what would be the usual distance that an external window sill would protrude from the wall?
Any help appreciated.

 

[noseall]

there are a lot of variables here gcol.

when i started building, cavities were 50mm. thats 250mm of masonry plus 18mm of float and set plaster. so the total thickness would be around 270mm average.

today we are building with 100mm cavities whilst using dot 'n' dab plastering. that's 300mm of masonry plus 25mm of plastering.
so the total thickness would be around 330mm average.

there are stub sills and regular sills, wood sills and plastic sills. building control like windows fitted these days so that the window is situated partially over the cavity, as to avoid damp bridging.

i would put the average sill overhang at 50mm.
ish.

 

[gcol]

That's just what I was after noseall - that gives me something to work from.