We are building an extension to our home and the extension has a flat concrete roof. We would like to plant a lawn on this roof. Structurally the roof can handle the weight but now I have a few growing lawn related queries:

  1. What soil depth should we allow for?
  2. Are there any specific drainage systems to use?

I've read about specific soils to use and use a shallow rooting grass, however, I'm still not certain on the depth of soil required.

Thanks Rob

  • Sounds like a good place for artificial grass. The only sod roofs I have seen were pitched. – blacksmith37 Oct 10 '20 at 0:28
  • You might want to consider a "green roof" instead, which in your case means a roof that contains primarily sedums. Here's some information: sempergreen.com/us/solutions/green-roofs/everything-about-sedum. Just from a practical POV, how would you mow a grass roof? The only one I've ever seen was pitched and mowed by goats. – Jurp Oct 10 '20 at 13:56
  • @Jurp the extension is in a sloped section of the garden to the roof extends existing lawn. I think I may need to go with artificial grass but would have preferred a natural option. – Rob Curtis Oct 11 '20 at 7:58
  • Well, there are grass-like sedums (e.g. Sedum sexangulare) that make excellent and fast-growing groundcovers. Of course, these bloom (the one I referenced is bright yellow) and then the faded blooms turn brown, so that could be a deal-breaker. One other option would be blue-eyed grass (Sisyrinchium), which looks like grass and also blooms, but in this case the blooms fade to green seedheads and are not particularly noticeable. Not as quick of a groundcover as the sedum: if you were to over-seed you could probably get a lawn "look" in a year or so. Just a couple of other options for you. – Jurp Oct 11 '20 at 13:23
  • thanks @jurp I will check out the options we have available in our country. – Rob Curtis Oct 13 '20 at 2:20

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