In article , "Dave P"
says...
Time has come to replace my rotting timber single-glazed windows with modern
uPVC jobs; the only question is whether to diy or (argh) get in a Window
Replacement Company.

Problem is that I've discovered that although there are (concrete) lintels
fitted over the inner leaf of the cavity wall, there ain't nothing over the
outer leaf. Now, I have absolutely no doubt that if I go to a
FENSA-registered WRC plc, they will happily bung in new uPVC ones without
adding lintels, and until the frames start sagging in the middle, nobody
will be any the wiser. But if I diy, then I have to go through Building
Control don't I; and you can bet your life they will insist on lintels being
put in.

Surely if you just repair the existing windows rather than replacing
them then nothing's changed and everyone's happy? Sounds like you're
not too bothered with the result as long as it doesn't involve hassle
and great expense.