Shed Roof

Are you going to use loose soil and then scatter grass seed, or use turves? I would suggest you use the latter, so that the grass roots bind the soil from the start and stop it washing away, but I have no particular experience of your problem.

I thought, a shed question - I know about them.... then the green roof bit... them I don't know and have no experience of, so this guidance is probably worth what you paid for it!

With my limited understanding, the green bit is usually made up of many layers. So you already have your waterproof one the EDPM, then you normally have a root barrier as a last line of defence to protect it.

Then you need a drainage layer - that lets excess water drain easily. (you can buy pre-made forms for this)

From a look about it seems that designs vary - but a water retention layer, possibly with a geotextile filter layer to stop soil migrating into the lower layers. Then you peat / soil, plants, and any other dressing.

This looks like a reasonable summary:

Looks a bit minimal for a green roof? when I was looking into it, seemed like the recommendation was a 4" dam round the edge to retain the growing medium and let it hold onto water, one system I considered was the Wall-Barn M-Trays.

Perhaps he implicitly assumed you would invert-gouge the batten edges as one of your jobs

I think you will have to ask him, otherwise you might waste all his good work and intentions.

Probably . . .

Sounds like a good idea. But something I think is the case is that the topping needs to be low fertility, and planted accordingly. Otherwise weeds take over.

Yes - but he said not to bother. Hance my additional concern about the sharp edges.

Yes - seen that, thanks. At the moment he's just left me with: add some low fertility soil and some sort of low weight mix - take advice from specialists. I think I'm just going to get rolling eyes when I start talking about the roof construction . . . but hey, worth a try maybe.

Yes - bit deep for my roof, but looks like it sort of self edges, so maybe I'd get away with it. And could always add a couple of battens. But over £1000 for a 4 x 3m roof . . .

Yes, probably best - but he'd likely just tell me it's all fine and to move on. Just wondering if there's any experience/insight here.

I bet someone on the Faroe Islands could give you chapter and verse.

Construction: Modern methods use birch bark, felt paper, plastic, and netting to support heavy sod. The roofs require strong wooden substructures to handle the weight of the soil and, in some cases, snow.

Benefits: Beyond aesthetics, they serve as excellent insulation, protecting against cold and wet weather, while also providing soundproofing.

Maintenance: These roofs require regular maintenance, often including mowing the grass.

Have you given any thought to how you are going to mow it?

ISTM that you are going to need a retaining batten at the bottom edge of the roof to match the side ones, so as to retain whatever you place on top of the roof at the very least.

It's designed to take 400kg m2 by my (AI) estimate - so roughly double the loading of 5cm wet soil and a foot of snow. In a gale. At least that's across the joists. The stud work looks very odd to me, now the openings are in. Strength in compression seems to put a lot of spade work on just a couple of vertical studs and window frames. But as I mentioned, the guy who designed it is (or rather was) a civil engineer, so I'm keeping out of that side of things.

Environmental reasons too - use that large space to nurture flora/fauna.

Looking at this at the moment -

Well, it's not a lawn. But I can get up and down quite easily with a strimmer should the need arise.

Yes, that's what I thought. But I think that'll compromise run-off. Thinking now about:

Goat ?