On Sun, 21 Oct 2007 15:09:49 +0100, "Brian G"
wrote:

I bought a pair but I notice the holes do not line up with the ones in
the original. Is this a problem? What is behind the uPVC? Is it a
wooden frame? If so, could I just put the screw where the new holes
are?

Just insert the screws into the frame using the holes in the new hinges -
different makes have different locations. Just remember not to overtighten
the screws as the 'thread' will easily strip in the uPVC.
[...]
Generally nothing in the uPVC - unless the window or sash is of such a size
that it needs reinforcement - and that will usually be either steel or
aluminium.

Thanks for your advice.

Is a upvc window just a plastic frame then? I never knew that. I
always thought the plastic covered a frame of wood or metal or
something.