Dave Liquorice wrote:

Andy Burns wrote:


a 1/4" tongue of weetabix doesn't have much strength,

True but the T&G on weetabix is more like an inch and half with quite
on offset between sides and the toungue/groove tapered.

My loft boards are 3/4" (green flooring chipboard is 22m or occasionally
38mm).

https://www.homebase.co.uk/chipboard-loft-panel-board-1220-x-320-x-18mm-3-pack_p404607