The green roof part of our build goes on next week.
Build up is Joists, Ply, vapour layer, insulation, membrane. We used Bauder.
Next week they do electronic testing to check for any leaks before the sedum goes down.
The green roof buildup (not the normal flat roof build up) seems to be coming out about £150/m2 - we are doing 30m2). Delivery of the material to site and getting it up on the roof is a costly part - Bauder green roof comes in rolls.