After a short break whilst I was catching grass snakes on the M25 we have finished building the green roof. The final part involved mixing a substrate with a 20-30% organic content, we managed to find a local source of hardcore to mix with this and create something for growing in.
It took a while to get the stuff up there as we didn’t want to carry heavy buckets up to the roof. Once we had filled in the gaps between the drainage pebbles we sowed a wildflower mix. Finally we added a few areas of crushed brick and a log to provide a few habitats for invertebrates. We finished just in time for the weather to break and along with the thunder and lightning there was plenty of rain to help it all bed in. Now we just have to wait and see what grows.
Just a quick one, not finished yet but the roof is progressing nicely, we have the sedum in place for the middle of the roof and drainage channels laid out in pebbles across the rest of the roof.
Now all we have to do is add in soil from the garden in the gaps so it will grow a range of native plants. As this will involve a fair bit of lifting we are going to get some people round for a green roof party and they will all help moving the stuff about.
I have been planning to make a green roof for a while and this week events overtook us as the roof I have been planning to use sprung a leak in the rain. This meant bringing everything forward but was a useful method of avoiding procrastination. However it did mean we needed to re felt the roof before getting started on the green roof bit.
So I stripped the felt on Tuesday between further rain and cleaned off the roof. This revealed a number of boards that had to be replaced. So ripping and measuring took place.
Whilst we were doing this we took advantage of the holes in the roof to work on another aspect of the retrofit, insulation. There was plenty of room in the roof for insulation but without taking the roof off, no way of getting it in there. I suppose this means the leak did us a favour but still quite hard work. But we did manage to get 200mm in across the whole roof which should make a big difference come the winter.
We have checked the strength of the roof and because the joists are quite close together (320mm) we should be able to get something a bit more substantial than a sedum mat for some of the area at least and are planning a wild flower area with some sedum in the middle to keep the weight down. The new boards are in place and the butyl liner is due next week so we should have it complete pretty soon.