This time, the idea for making yet another green roof at our place came out of necessity. We have a garage whose flat concrete roof has been leaking for some time now. And instead of pouring just another layer of concrete on it, we decided to cover it with something more beautiful.
The structure is firm and stable, made out of bricks and concrete, so there were no worries that it wouldn’t hold the weight (green roofs weigh about 60-120 kilograms per square metre). We also happened to have some wooden boards just waiting to be used, and they seemed perfect to make a small inclination (just enough to let the water slide off).
What was supposed to be a weekend workshop turned out as a two-week intensive course for our wwoofers, Lisa and Stef. The first step was sanding the boards and painting them with a protective layer that protects them from woodworms, as well as prevents the growth of funghi and molds.
Once done, we assembled the wooden structure to make the roof inclined. We covered it with bitumen (tar) foil and water storage playstic before covering it with turf. Of course, the digging of the turf also took quite some time. In the end, we planted some succulents and sedum on the roof, something which we will repeat again in autumn and spring, given that July is not the best time to plant.
Following are some information that you mind find useful if you are planning to make something similar.
Size of the roof: 5×10 metres
Time spent: (please note, there was a different number of people included at different stages, the hours listed are an approximation of overall time needed for each process)
80 hours for preparing the boards (sanding + painting)
60 hours for constructing the inclination
85 hours for removing the turf, covering the roof with hydroisolation and turf
8 hours for closing, assembling the perimeter, solving the details, placing gravel and planting
Costs: (this is what we spent for this project, but have in mind that we already had the tools and some material, and the wood that we used for making the boards was from a tree fallen in our forest)
Sawmill 80 € (2,5 m3 of wood)
Protective paint 60 € (30 l)
Tar 70 € (50 m2)
Water storage layer 75 € (50 m2)
Screws, nails and other supplies 20 €
And the final result… Priceless!
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