Double Glazed French doors

Hi Guys,

In the process of building my extension in which will hopefully sit a pair of external upvc french doors. The extension has a 90mm cavity all round, my question really is were abouts should the doors sit in relation to the opening (i.e. on the inner skin, outer skin or over the cavity).

if it is on the outer skin for arguments sake what do i do about covering the cavity especially in the floor ???

Cheers in advance
Stan.

The doors would normally be fitted on the outer skin of brick work not to the front face but set back approx 25mm. to close the cavities at the side the correct way would be to fit a cavity closure to suit the cavity size and the same for the bottom then fit a window board closing the cavity and also bridging the frame back over the cavity. then you can plaster board the sides and head up to the frame .