Jump to content

Green roof


eandg

Recommended Posts

Am I correct that if you're just going with a basic sedum then it's a case of getting a bog standard flat roof (sarnafil etc.) installed and then you can diy install the sedum on top? Or is it a lot more complicated than that?

Link to comment
Share on other sites

If you want your sarnafil guarantee to hold up you’d be best to compose your green build up in accordance with Sika’s notion of how such things should be done.

Also be aware sarnafil needs a root protection layer and i’d Personally suggest you use the sarnafil product (again for guarantee reasons).

Look at the Bauder system equivalent to sarnafil......I think cheaper and better, I have both.  The Bauder has a compatible thin build sedum system that’s real easy and light.

Link to comment
Share on other sites

  • 4 weeks later...
On 08/02/2019 at 20:10, mvincentd said:

If you want your sarnafil guarantee to hold up you’d be best to compose your green build up in accordance with Sika’s notion of how such things should be done.

Also be aware sarnafil needs a root protection layer and i’d Personally suggest you use the sarnafil product (again for guarantee reasons).

Look at the Bauder system equivalent to sarnafil......I think cheaper and better, I have both.  The Bauder has a compatible thin build sedum system that’s real easy and light.

Thanks, will have a look.

Link to comment
Share on other sites

Hi

I have planning permission for my new build, it's a flat roof bungalow, total roof area approx 100m2. I would like a green roof, and have presumed that it will be an extensive one, probably in the 500mm x 500mm trays that you just stick together on site. 

 

The advice I have received from a couple of green roof tray firms is that (other than ensuring the roof can take the weight) I should just build to normal standards and then plonk the trays on top later. For me this might mean posi-joists, then 100mm insulation, then board, then GRP. I would probably have a normal 1:40 run to gutters and a downpipe. That is certainly what I'd do if I didn't have the green roof aspect, though only because it is what I am familiar with. 

 

My question is: Am I missing a trick here? Do I have clever options at my disposal? I'll never see the roof surface once its under the tiles, so all I'm interested in is the waterproof performance, and can I get that cheaper than with GRP? Do I really need to build a roof like normal, or is there a better way?

 

I also wonder if I need normal gutters etc? Would I get away with a couple of downpipes, or even chains, from the edge of the roof given how much the green trays will soak up?

 

I don't have an architect to design this, as this is a small project which I am desperately trying to keep very simple!

 

Thanks

Link to comment
Share on other sites

 The storm style rain we seem to get these days and will likely get even more in future,  strikes me as rendering irrelevant the notion that a green roof halves run off ...... when it’s saturated it will shed water as usual so I’d gutter it as usual.

ignore the tray providers opinion...ask the membrane manufacturer what’s acceptable.

1 hour ago, Tony K said:

Do I really need to build a roof like normal, or is there a better way?

Well, you surely want normal+ ....I don’t see having a green surface provides any opportunity to cut corners versus a standard flat roof.

Link to comment
Share on other sites

Thanks. I should have phrased that better! I'm not suggesting I should cut corners, I'm thinking more about whether I'm going to double up on a part of the roof by the time I've added the bits that go under the sedum. 

 

Does anyone have any spec for a diy sedum roof?

Link to comment
Share on other sites

 Sedum will be in growing medium and the growing medium will either be in trays or it will be on a route protection membrane/barrier,  and this lot will be on your waterproof membrane (of single ply/GRP/felt/rubber/whatever ).

 It is possible to have a waterproof membrane that incorporates its own root protection into it,  but that’s not the most typical situation.

 It is also possible that you might choose to incorporate other layers between the growing medium and the root protection... such as water retention/ drainage mat( possibly sandwiched between the fleece).

If you don’t want to just follow the rules big roof membrane co’s lay down in order to maintain their guarantees, Charles Fentiman might be a good one to consult: http://www.greenroofsubstrates.co.uk/

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...