On Sunday, 1 November 2020 at 07:29:16 UTC, Andy Burns wrote:
John Rumm wrote:

The board to board joins have the T&G profile and so don't need extra
support.
Stagger the joins, but a 1/4" tongue of weetabix doesn't have much
strength, so only tread where you can see screws into the joists unless
you're slimmer of the month ...

Because the pitch of our roof trusses is a mere 22deg there is no part of our loft that you can stand up in. However, to enable me to crawl easily about the loft to do wiring I boarded the central portion so that I could easily crawl without getting tangled with the rock wool. I simply fastened 3 X 2s to the side of the trusses at 300mm above ceiling height and used chipboard loft boards as the floor. It did mean shortening every one of them and losing about 300mm each time also not helped by the uneven spacing of the trusses. It did reduce head room considerably with me just about able to kneel in the very centre but it made subsequent work so easy. Once we complete work in the loft which will involve dropping a couple of cables into the bathroom and providing a ventilation system for the bathroom I have no intention of using the loft.

Richard