I mentioned in another thread that I'm converting my sectional concrete
garage into a workshop. Today went well: five of the concrete panels came
out (intact) and a timber frame (assembled in situ) is now secured into the
gap. The centre cross-ways rafter has been attached to the top member of
the frame (having been held up in the interim by the excellent Lidl ceiling
prop: a splendid tenner's worth).

The final task for today was to fit the secondhand uPVC window into the
frame.

Unfortunately, the window is 1/2" wider than the aperture in the frame. It
must have grown since I measured it.

I really don't want to have to remove the entire frame, take off one (or
both) of the side verticals, trim it (or them) down and then put the whole
thing back again (but that might just be because I'm tired and annoyed with
myself: I could well feel differently in the morning).

Here's the frame:
http://i246.photobucket.com/albums/g...Theframe-1.jpg .

How practical would it be to cut down the frame in situ? I suppose I could
drill a series of small holes, chisel them out to form a gap and then use a
handsaw. Or... I've never done it, but can you use a circular saw like a
chop saw, to start a cut away from a corner? I'm not desperately keen on
the notion of using a heavy and powerful circular saw vertically, though.

Any thoughts will be very welcome!

Many thanks,