A living green roof consists of layers of materials that all work together seamlessly to protect your waterproofing, insulate your building and nurture the plants.
Having your green roof delivered in kit form
Here’s what to expect when your Enviromat DIY green roof is delivered……
Delivery: The kit will be palletised and will be delivered by an articulated lorry – unless of course you’ve warned us about access problems, in which case we’ll make sure we send a smaller vehicle.
A pitched green roof kit ready for despatch. No drainage mat in this kit – it’s not needed on a slope
Delivery is kerbside only. The driver will leave the pallet as close to your property as possible but cannot bring it onto your drive and certainly can’t wheel it into your back garden. You need to make sure you have a way of carrying the kit components to where you need them to be. Some of them are heavy and need two people to lift them.
Lifespan: The sedum matting part of your kit is very perishable. It needs to be unrolled on the day it is delivered. No worries if you can’t install it straight away but lay it on the lawn or the drive and unfurl each roll so that the plants can see the sun.
Instructions, edgings, tools and safety gear: Instructions should be included in the kit, if not, you’ll find them on our website. We don’t supply edgings (but we can recommend a supplier), tools or safety gear. You will need: strong scissors, sharp knife, sturdy boots, gardening gloves, a head for heights, somebody to help you, lifting gear – to get everything on to the roof – and anything else that your site manager insists upon. Never ever compromise on safety.
What’s in the kit?
Polyethene to protect your waterproofing
Most important thing to note here – this is NOT waterproofing. It will not make your building watertight and it will not fix problems with the existing waterproofing. This is simply a root barrier to prevent damage from plant roots.
This layer needs to go on top of your existing waterproofing before any of the other layers are added.
A layer of heavy gauge polyethene is being used to protect the waterproofing on this demonstration table at the Enviromat production unit.
Here’s a hint from an experienced green roofer – the poly layer can be slippery to work on (and therefore dangerous); If you sprinkle it with water before you walk on it, it somehow becomes less slippery. You might get wet knees – but wet knees are less of a bad experience than falling off a roof.
A pitched green roof doesn’t need any extra drainage, so this will be missing from your kit.
Drainage mat is essential on a flat green roof. Sedum plants can’t bear sitting with their roots in water for any length of time. This will ensure that excess water is taken off the roof as quickly and as efficiently as possible.
Drainage mat is unrolled directly onto your polythene layer.
It’s quite light so you might want to put bricks or something on top of it to stop it blowing away while you’re working.
A nice little feature of this product is the anchorage flaps on the back. There’s an extra piece of fabric folded under the long side of your drainage mat. Unfold it as you’re working and lay it flat on the roof. The next piece of drainage mat sits on top of the flap and the “springy” bits in the middle butt up close to each other. That way you’ll have no gaps and the two pieces help to hold each other down.
Drainage mat – a layer of nylon loops sandwiched between geotextiles. Notice the anchorage “flap” on the right hand side of the picture.
Water retention matting
A lovely recycled blankety fleece that holds water beautifully. I know, I know, I know. You’ve just laid drainage mat because you’ve been told that too wet is bad for the plants. Well so is too dry! This fleece has been specially engineered to hold just enough water to sustain the plants and prevent rainwater gushing off the roof. This’ll release water gradually so as not to overwhelm the gutters but it also acts like a wick to draw excess moisture away from the plants’ roots.
On a pitched roof you’d be lost without water retention matting. If the pitch is over 10 degrees or so, it’s well worth using a double layer of this.
Sometimes water retention matting is stitched to the back of Enviromat sedum matting. If you can’t find it separately in the kit – check to see if that’s the case before you start worrying.
The layers of a flat green roof: from the bottom up: Waterproofing, polyethene, drainage mat, water retention mat, sedum matting.
The pretty bit! This is the heaviest part of your green roof kit. You need to be very careful when lifting it and when placing it on the roof. Either lift the rolls and lay them one at a time or lift all of the rolls up onto the roof and dot them about. If you stack them all in one place while you’re working, you’ll put an awful lot of strain on that one area of your roof. That’s what caused that disaster in Taiwan a few years ago when a whole supermarket collapsed as the green roof was being installed.
Green roof feed
Not a standard part of the green roof kit but hopefully you will have thought to order some. A 2.2 Kg bucket treats 26m2 of sedum blanket. If you empty the whole bucket onto a smaller green roof you will kill it. Be very careful to only apply the recommended 85 grams per square metre, then seal the bucket and save the leftovers for next time. It stores beautifully.
How to install your living green roof
This video is well worth watching before you begin work. Note how Mark is working on his hands and knees with his feet pointing towards the edge of the roof. That’s so he can always feel when he’s close to the edge and therefore reduce the risk of tumbling off.