turf

The small shed at 3.6 x 2.4 m is just about complete. Made up as a prefabricated kit the sections were taken down to the plot on the Cabstar before assembly on pad foundations - nine concrete filled sections of reclaimed fish farm pipe - 35cm diameter. The roof trusses were prefabricated in 150x50 C16 timber - somewhat over the top but designed to take the very heavy weight of a wet turf roof.

We finally completed turfing the shed roof this morning. After a rainlashed night the ground was pretty wet but we still managed to cut the last couple of square metres, trim them off and get them on the roof. The weather has made it a bit of a stop go process this last week. We put the edge trim on this afternoon and only need to line the two drain hoppers to seal the whole thing.

The roof is the prototype for the big shed following next and then the house. The specification is 18mm OSB over the trusses, then a woven polyester/PVC pond/reservoir liner as the waterproof membrane. We have placed a wool mulch mat over this to retain moisture and provide nutrients as it rots down over the next couple of years. Over that is a layer of coir fibre biodegradable mat. This is to prevent the turfs from slipping on the 26° roof pitch and bind the roots of the turf layer as it grows. The pebbles allow runoff to drain to the gutter hopper.

The turfs are hand cut for this roof but the others will be machine cut. These ones are a bit more variable in thickness and are taken from the actual footprint of the smaller roundhouse. We should have some lovely meadow flowers - tormentil, eyebright, harebells and the like on the roof this summer.