In article .com
, writes
fred wrote:
In article , Mark Hindley mark@hindle
y.spamnospam.uklinux.net writes
Would 4mm exterior ply be sufficient?

Overall it sounds like a nice solution although I might have gone for
something tougher for the waterproofing but I'm not exactly sure what.

On the 4mm question, I suppose it depends how flat the flat roof really is, I
assume there is a small fall to shed water. If you use 4mm then you risk
pulling dimples into the surface at the fixing points, when you tighten the
screws, and water may end up pooling there. If you use 12mm then I think
you would avoid that.


could you use 4mm and glue it? never tried it

I thought 12mm would be more resilient over all, particularly with the
prospect of ongoing works, steps bearing etc, just too much capacity for
doh! factor with the thin stuff.
--
fred
Plusnet - I hope you like vanilla