"Bod" wrote in message
...

He's talking drivel.
Windows are to keep the weather out, as is the outer leaf.
Hence the window has to be linked/continuous with to the outer leaf.

Plastic windows are a fire hazard.
The plastic gives off highly toxic fumes in a fire.


Are all of your window frames wooden or Crittal steel then?

mine a quality NorDan windows fitted behind the vertical dpc of the
cavity
closure rebate .....


So they are plastic then, unless you have the aluminium cladding?

no...timber


and if you have a concrete boot lintel (with a normal lintel in the
outside
leaf) with a dpm over the boot lintel coming out in line with the cavity
closure dpc ...if you fit your window in the outside leaf you may have
water
appearing inside the house above the window.....


Well I've never heard of a double glazed window leaking from above a
window when fitted to the outer leaf.

There is a cavity tray above windows to divert any water outside through
weepholes.
http://en.wikipedia.org/wiki/Cavity_wall