bathroom sub-floor - is 18mm enough?

[rhinatron]

Hi all,

I've asked a question about this before, but thought I'd start a new thread to keep it cleaner (thanks to all who responded before)

we're laying a new bathroom upstairs, and I wanted to know what thoughts were one thickness of ply?

it's going direct on joists (450 centres) and will have a few rows of noggins across floor. We're fitting mosiac tiles on the whole floor with flexible adhesive.

I've heard 18mm wbp willgive too much movement, but is this the case with a mosaic tile? If we're supporting the joints with noggins will that negate the need for 22/25mm?

thanks in advance!

 

[jobdone]

It's all down to deflection. If the floor is rigid then I would put noggins at 300 centres. How are you planning on decoupling the tile and timber?

 

[Bond]

As above it’s all down to deflection, 18mm ply with noggins and a 450mm. Centered joist , should be adequate, if in doubt use 22mm ply, or 25 mm if you must.

 

[Old Mod]

If you have the budget, forget the 18mm ply and use 19mm hardifloor, it’s as solid as it gets.
It’s structural flooring, and worth the investment.