22 November 2020 | by Cllr James Meek
I had tiled the roof of my garage ages ago, but was having problems with leaks, so knew I was going to have to strip it all off to remedy the problem. When it came to it I thought it would be better to have a living roof than boring tiles, so set about thinking how to do it.
Green roof structure.
If you go online there are modular sedum packs you can buy to install on a sloping or flat roof, but these are quite expensive. You can also buy sedum matting which has sedum seeds sandwiched in it to make the process easier, but these are expensive too. As the garage roof is really quite large, being very long, I decided to just do it gradually and grow it slowly.
I had been saving plastic soffit and facia boards left over from our extension and others which I’d found in skips – hate the thought of it all going to
The finished rooflandfill –so decided to cut them up into strips to make a grid to provide a structure for the living roof. The vertical strips are deeper than the horizontal ones, allowing for drainage on the slope.
I then needed to make sure that it would in fact drain so needed some resilient material to raise the membrane I was going to use off the roofing felt so that there was an air gap. I had some aerated building blocks and a neighbour then mentioned he had a whole lot behind his garage and was glad to get rid of them, so I ended up with plenty. They are used as internal insulation blocks in house construction and are quite light and water resistant, so I decided to cut these up into narrow strips. This was quite tricky, but I used a concrete hand saw to make the initial cuts and then cut those further on a table saw with a multi-purpose blade. The dust was a problem, but I just did it on a windy day and held my breath!!
The finished roof.
I used some gardening membrane which I had left over from a landscaping job and lined each square with this laid over the strips of block. I then sieved compost from the Beddingham Green Waste recycling plant, using the chunky material as a base and the sieved, finer compost, mixed with some garden soil and perlite, for the top layer. The perlite came from a kitchen ceiling which had collapsed and had been the insulation layer. Perlite is good for that, but also has amazing water retention properties and should help plants survive in drought conditions. It’s often used in hanging baskets.
I’m now gradually stocking the soil with drought tolerant plants like semper vivum, sedums and stonecrop. The latter I keep finding on the ground by the house where the birds have flicked it out of the gutters! I’m gathering sedums from friends’ roofs and I was a given a few semper vivums which prolifically produce off-spring.
It has been a lot of work, and now I have a problem with the local cats getting up there and digging holes to do their business, but I think it’s better than a sterile tiled roof. I might have to put wire mesh over it to discourage them. It will take a fair time to establish, but it hasn’t been expensive and is mostly made from saved and reused materials.