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Green roof costs


mjc55

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Looking at costs for installing a green roof on our new build and I have been quite surprised at the costs being mentioned on the (many) suppliers websites.

 

£100 per sq. m. seems to be average and given that we are planning on having around 250 sq. m. of roof or so (large overhang at rear - about 2.5 metres or so) then we are looking at around £25k or so to do this.

 

Would be interested in hearing how others have gone on taking this approach, whether employing someone to install or self-install (our preference at this stage).

 

I know that there are some on here that don't seem to think that a green roof is a great idea, and I am not averse to having that discussion, but the main thrust of this post is to try and get a feel for the "real" costs of a green roof.

 

Thanks in advance.

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47 minutes ago, Thorfun said:

£100/m2 seems quite cheap. Does that include insulation, waterproofing and the green covering or just for the greenery?

That's what I am trying to understand!  Have to say that I am finding that price quite high for what seems like a reasonably simple solution!  Given that turf costs a lot, lot less (I know it's not exactly the same thing) I don't quite see why green roof solution costs upwards of ten times the price?

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2 minutes ago, mjc55 said:

I don't quite see why green roof solution costs upwards of ten times the price

Put a tray of light soil, 7 metres up from the ground and watch what happens.

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45 minutes ago, mjc55 said:

That's what I am trying to understand!  Have to say that I am finding that price quite high for what seems like a reasonably simple solution!  Given that turf costs a lot, lot less (I know it's not exactly the same thing) I don't quite see why green roof solution costs upwards of ten times the price?

yep. it's a pretty simple solution albeit with lots of layers. I could've done it a lot cheaper myself but I wanted a guarantee for the flat roof covering (was also required for our warranty) so I got a professional to do it all. from insulation to waterproofing to green roof to edgings etc. including the hire for a telehandler was about £400/m2 to give you an idea. so, as I say, £100/m2 seems pretty cheap.

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Looked in to this. Sedum plugs are much cheaper than the mats. Just need to be a bit more patient and do more maintenance in the first year. I think green roofs are great when done right. Go for it.

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1 hour ago, Thorfun said:

yep. it's a pretty simple solution albeit with lots of layers. I could've done it a lot cheaper myself but I wanted a guarantee for the flat roof covering (was also required for our warranty) so I got a professional to do it all. from insulation to waterproofing to green roof to edgings etc. including the hire for a telehandler was about £400/m2 to give you an idea. so, as I say, £100/m2 seems pretty cheap.

So what was the roof makeup before the green roof got installed?

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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. 

 

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39 minutes ago, mjc55 said:

So what was the roof makeup before the green roof got installed?

A timber frame

 

 

Edited by Thorfun
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1 hour ago, markharro said:

Thats interesting - how does that work?

I'll let you know next week....it apparently can pick up a pinprick hole! So have been recommended to do it, before the Green Roof goes down.

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  • 4 months later...

Still thinking about our "green" roof!

 

So i understand the difference between intensive and extensive roof coverings.  Now I am coming across "bio-diverse" and "brown" roofs!

 

Bio-diverse seems to be coverings that are local to the area - something that we are keen to do - but brown roofs seem to be a subset of bio-diverse that rely on local windblown and bird carried seeding!

 

Any experiences or thoughts welcome.

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46 minutes ago, mjc55 said:

Still thinking about our "green" roof!

 

So i understand the difference between intensive and extensive roof coverings.  Now I am coming across "bio-diverse" and "brown" roofs!

 

Bio-diverse seems to be coverings that are local to the area - something that we are keen to do - but brown roofs seem to be a subset of bio-diverse that rely on local windblown and bird carried seeding!

 

Any experiences or thoughts welcome.

I've used the sedum blanket systems before. Pretty straight forward to install but if I did it again I'd put irrigation in as it can dry out in the summer. Check out 'skygarden' they do supply only and supply & fit.

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2 hours ago, mjc55 said:

but brown roofs seem to be a subset of bio-diverse that rely on local windblown and bird carried seeding!

If it was on the ground, it would be called scrubland.

Though they do say that a weed is only a plant in the place you don't want it.

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10 minutes ago, SteamyTea said:

If it was on the ground, it would be called scrubland.

Though they do say that a weed is only a plant in the place you don't want it.

That would probably be my view as well.  Given the current state of our plot it would probably end up mostly thistle, nettle and bramble!

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Just now, mjc55 said:

bramble

Boil the fruit with lots of sugar and call it jam.

 

For some reason, we are being inundated with flies this autumn. While I like the idea of a green roof, not sure I want to attract critters close to my bedroom window.

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Our builder installed this system, https://www.greenroofsdirect.com/products.   
 

but we added additional soil under it and put down additional wild flower seeds. 

 

it’s sitting on a single ply (memtec) warm roof.
 

only a small area.  The photos are  April 24 when it was laid and June 24,  by July it had lots of cornflowers and other plants.  It’s still going strong and will need to climb on to cut it down in the next couple of weeks, in preparation for winter. 

 

 The builders laid it, we could have done it, but as they were up on the roof we thought it easier for them to do the lifting.  
 

image.thumb.jpeg.7b4228b49213748fce59f0d2bd2957ea.jpeg

 

image.thumb.jpeg.3de91999a435a51ffc9d0eab34f2af61.jpeg

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29 minutes ago, SteamyTea said:

Boil the fruit with lots of sugar and call it jam.

 

For some reason, we are being inundated with flies this autumn. While I like the idea of a green roof, not sure I want to attract critters close to my bedroom window.

No flies on me @SteamyTea 😁

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There was a 'gardeners question time' item on green roofs last week. The wild flowers were being wiped out by grass.

The answer was to stop watering it and leave it to its own devices....it is not a garden.

 

A 'brown roof' is gravel and sticks and silly.

I've done one green roof, which our client's original architect had shown. We were stuck with it.

I learnt enough to know all the reasons not to do it.

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