Now it’s lighter in the evenings I’ve had time to get the ply on the roof. I’ve chosen to go with 12mm external grade ply as it’s stiff enough not to bend under the weight of the rubber EPDM roofing membrane.
The ply went up without any issues and is screwed at 300mm centres into the CLS rafters. Building the roof to exactly fit 4 full sheets of ply saved time and no cuts were required.
Sitting up on the roof was less scary than I had imagined and the overall structure is very stiff.
Next step over the next couple of days will be to staple the breather roofing membrane onto the external face of the walls and then nail the batten to the uprights. This will provide a gap behind the larch cladding to allow any moisture to escape.