Replacement Windows on a rendered house - Rehau 60mm or 70mm - ease of fitting.

@Mr. Handyandy or anyone else in the know.

Firstly thanks again for all your previous help (and others)

I wonder if you could clear up another layman's confusion with the measurement of the windows for me.

For the quote i was told to take the measurement from the inside only - but on measuring the outside, purely for comparison purposes, i noticed that this measurement is always larger.

For example on a 3 pane window its width is 176cm on the inside and 172cm on the outside - a difference of 4cm.

So my 'stupid' question is - if the windows are only measured from the inside (i had a quote a few years ago the surveyor also only measured from the inside) - and the inside is smaller than the rendered outside - how will the window stay in?

Won't there be a big gap around the outside that would need filling - i.e. rather than the window fitting into the original gap; which i originally thought would make fitting difficulties (see OP)?

Apologies, if I've missed something very obvious here.

Thanks again for any advice - or an explanation of what may prove to be the bleedin' obvious

 

Thanks for your detailed reply @Jord86 - that's helped me picture the installation process a great deal, regarding render issues, and cleared up my confusion.

And thanks to everyone again who replied to my OP - really is a great forum/community, really appreciated.

Cheers.