On Mon, 22 Oct 2007 13:19:17 +0100 Brian G wrote :
That's all a UPVC frame is - a hollow, extruded lump of plastic
that comes in various shapes and sizes - have a look at the profile
here http://www.qualplas.co.uk/windows.html

Larger ones do have metal reinforcement in the cavity, but the
opening lights are held square by the glass, thus the need for
accurate placement of spacers.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk