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Making a green roof

One of our volunteers, Gill, has written an article on her bee-friendly green roof for us. Read on to find out what she did and how it's helping the bumblebees.

"We are quite excited here in Nottinghamshire! Bumblebees of various kinds are busy feeding among our cottage garden flowers such as comfrey, foxgloves, honeysuckle, weigela, single roses and campanulae.

The next delight is going to be much buzzing on our sedum roof! Sedum of 15 different types arrived in mixed ‘turfs’ three years ago and was installed on the slightly sloping (3 degrees is optimum) flat roof of our new south-facing extension, which is coated with a waterproof membrane a bit like fibreglass with a rubbery grey resin.

Currently, the sedum is in bud and one can see these buds strengthening in colour, ready to burst open.

The process of installing sedum is extremely simple, and its roots will do no harm to your roof surface. The first layer is of sculptured foam, such as sometimes used for packaging, with the sculptured side down. This allows rainwater to drain gently down the roof slope, while retaining just enough for irrigating the sedum. Then comes a layer of gritty substrate, and on top of that are laid the sedum ‘turfs’ themselves.

Various firms will sell you sedum turfs – or multiples of individual plants if you prefer - so it is good to get quotes from a few. You could install the turfs yourself, as we did; or they will do it for you. Probably the biggest challenge is getting the weighty bags of gritty substrate, and the rolled turfs themselves, up onto the roof. We used two ladders side by side – plus two strong ‘bods’! The unrolling was a doddle. The turfs flatten under their own weight, and very soon knit together.

We would warmly encourage you to think of a sedum roof. The sight of 12 square metres of glorious red, pink, white and yellow flowers covered in bumblebees and other pollinators, is pretty special. Sedum is evergreen, no maintenance is required, you’ll be contributing to biodiversity and providing additional insulation to your house".

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