UPVC Windows in an extension and position over cavity Post questions and find answers on glazing, double glazing, upvc glazing, conservatory glazing, fixtures and fittings etc....

[Rossitm]

Morning all. I’m after some advice on fitting windows in my extension. I read somewhere that the windows need to be 30mm over the cavity? Is this correct? I’ve changed all the other windows in my house and fixed to the inside of the outer brick. Does this mean these are incorrect? Thanks in advance

[stoneyboy]

Hi rossitm
The installation of replacement windows with the inner face flush with the inside face of the outer brickwork is not wrong. Ideally the windows should be installed to avoid cold bridging but in many cases it is a compromise because replacement windows are shallower than the original. Fitting a upvc strip around the inside of the window overcomes this issue.
Regards S