plywood subfloor expansion gaps

[Reynardine]

Would appreciate some guidance here. I am laying a new plywood subfloor onto existing joists using 8' x 4' sheets.

Would a 2mm expansion gap be best around each board to allow for plywood expansion? I would prefer to butt each sheet against its neighbour and leave no gap. Not sure what's best to do?

Also, what about the expansion gap around the perimetre of all laid areas. Elsewhere I have read that people leave anything from a 7mm to 10mm expansion gap. I know this gap will be hidden by skirting board but, again, I prefer to leave no gap. Gaps are my enemy since I want to eliminate noise from the floor below. What's best ?

 

[mattysupra]

you can fit net if you match the moister content of the plywood to the joists that are already there. In other words get the room to the correct living temperature and then leave the plywood in the room for a week or 2. It is always best to leave a couple of mm tho. Also depends on the size. If a 4x4 meter room then you can fit net or at least a couple of mm short, if the room is something like 10x4 meters then i would leave 5mm around the edge to be safe.