Has anyone put one on an outbuilding?

Thinking of having a brick outbuilding/garden room/den thing built at the bottom of the garden and I quite like the idea of a Sedum roof.

Does anyone know anything about these or have any experience. How do they drain? Do they need to be pitched? If so, to what angle? What did you put under it to stop it leaking? How long do they last?

I’m involved in a building down in Devon that is having one installed next week .
We have changed the way it’s done a bit and done away with 3 of their membranes.
(Is a 600m2 roof so a saving in the 10’s of thousands). This means they won’t guarantee the roof for water tightness etc, but the way we have done it means there is 0 % chance of water leaking through

This is the company we are using….. http://www.blackdown.co.uk/green-roofs/

Apparently there are companies all round the country doing these roofs now.
He did tell me that we are a long way behind Europe in using these , and that in Germany you are financially penalised if you create a new build and don’t use a green roof .

Yes, they need to be pitched, albeit a lot less than the equivalent tile/slate roof. Thick membrane leading into a gutter does it for ours. Old carpet on top, bit of top soil, and you’re off.

Point of note though – you will need to factor in the potential extra weight of wet soil etc when making calcs for the roof structure.

The extra weight of wet soil is a major cost increase imo.

Speak to my mate Timmy Tim, he grows sedum and will tell you what’s what:

https://www.yell.com/biz/riley-growers-newent-7680948/