the greenest option
What does "Drain and Vent" mean?
It means surrounding the sealed unit with nothing but fresh air. The more the better,
and providing adequate drain holes, so that water can get out if it does get in.
SupaSash surrounds the glass with an 8mm void draining to the outside. If water does get in, it can get out again, prolonging the life of your expensive double glazing.
UPVC and aluminium have always done this. SupaSash is the ONLY wood window that is in the same ball-park.
Choose your wood windows carefully.
SupaSash EXCEEDS Building Regs
without changing the appearance.
A SupaSASH upgrade from flat-pack to EXCEED the Building Regulations