Windows fitted to timber frame, then bricked up- how do I replace?

[charliegolf]

Our house is a timber frame, and when only the frame was up, the windows (uPVC) were fitted externally into timber 'cavity closers'. The brickies then bricked up, and the plasterers skimmed up. I'd like to change 2 of the worse ones (in en suites, so quite small).

What method would I use to replace? Would I hack off outside render and fix from outside; or hack off some pb and fit from inside? Thanks.

 

[Wayners]

Either.
Most fitters do from outside but you can get them in from inside.
You fitting yourself then getting building control to inspect?

 

[opps]

Photos might help.