project green roof

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It’s been pretty quiet in the garden over the last couple of weeks, mainly just just keeping on top of the growth with all the rain followed by sun, followed by rain, followed by sun…. The veg patch is a mass of things to eat – radishes, peas, purple broccoli and rhubarb, and the red currants, blackcurrants. gooseberries and strawberries (including some lovely wild ones) are all ripening fast.

A week or so ago we added some rigging and a balcony to the ‘pirate ship’ using one of the crates we bought off eBay for £10:

2015-06-20 18.11.56

I’ve been intending to add a green roof too, so now seems a good time to start. A lot has been written about the benefits of green roofs, and we need more of them. They are a great way of replacing some of the green spaces we lose each day through building, deforestation and pollution, to name a few causes. There are lots of websites showing you how to do simple ones, have a go! Start on your bird table if you like, or go straight to the shed. http://www.bbc.co.uk/gardening/basics/techniques/gardenstructure_greenroof1.shtml

Green walls are an option too – maybe not as grand as this one at the Rubens Hotel, London: http://www.theguardian.com/environment/picture/2013/aug/21/london-largest-living-wall-big-picture but you can buy pockets to go on walls at home: http://www.woollypocket.co.uk

I should say at this point that I’m making a green roof on a garden structure, which is a lot different to building a green roof on your house! Get an expert in if you’re considering doing one on your house, you don’t want it collapsing. Green roofs can get very heavy, especially when it rains, and a structural engineer will advise you on specific loads for a house. Even for a garden roof there are things to consider:

  • Is the structure strong enough to support it?
  • Will you need to reinforce it?
  • Will the plants get too much/too little water?
  • Is the soil likely to slip off when it’s wet?
  • What sort of plants do you want/have access to?
  • How can you stop the wood rotting or roots penetrating?

This is our roof as it stands:

2015-06-05 17.10.50

As you can see, it bows a bit at the front, so I’m going to reinforce it with some metal angle bars. I’ll use arris rail to create a ‘cradle’ (with drainage at the back), then put a liner down for insulation/protection against the existing asphalt, with a pond liner on top. The growing medium will be leca mixed with compost, keeping it light and suitable for sedum, which I’ll plant on top. Sedum are pretty robust, come in lots of different colours, flower at different times, and we have lots in the garden already that I can split, keeping the cost down. Here’s the plan, you can download it if you like:

Green roof plan

Green roof plan

We’re just waiting for the materials to come, so I’ll post again when it’s being built…

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