Afternoon uk.d-i-y people,

While thinking idly about extending my house,
I happened on the idea of having a patio on the
flat roof of my extension. Only problem is, all
the flat roofs I have ever seen in the UK have
that felt and membrane option where you either
(a) can't walk on it, or (b) wouldn't want to walk
on it even if you could.

In Europe I have seen patios on roofs where they
have a raised wall around the edges, slabs in the
middle, and a drain out through the side, at the
base of the wall. I think all of these buildings were
of entirely concrete construction, so I imagine that
the roof was reinforced concrete as well?

I googled a bit this morning, and found various
references to GRP or glass fibre membrane roofing.
One example is he http://www.flatroof.co.uk/
(warning: Flash-only and no HTML version).

I'm still pretty much at a loss though - what do people
here think is the best way of getting a patio on a flat
roof? Can anyone fill me in on the important issues
to consider? I'm very much at the drawing board
stage at the moment, so any advice would be helpful.

Thanks in advance,
Al