I have a lot of 3x3s from old pallets, 70mmx70mm, and spans of upto 2.2w1 meters for my bedroom ceiling.
On top I plan to put a layer of kingspan, and then Ply or OSB, then use it for storage.
Tony Brier wrote: Our old rule of thumb when I was a BCO which matched the tables pretty well was that for floor joists is double the depth in inches and subtract two to get the permissible span in feet; Which would give 2"x4 1/2 " for a room floor
Does the panel think the 3x3s will be OK, how close to each other should I put them/ The loft will never be converted into a room. [george]