What size ply do I need?

[essex_lee]

What thickness?
I am tiling the hall and kitchen and under stairs wc. There is tongue and groove boards down at the moment, I'm going to take them up and lay ply straight on the joists. What determines the size of the ply I lay?
I have 23sm to cover, any suggestions where I buy it?
Thanks

 

[Gazzer]

15mm is BS. But for this job I would use the thickest possible 25 mm.
While you have the boards up please consider adding extra noggins.

 

[essex_lee]

Ta.

What thickness is a floorboard?

 

[tobins tiling]

as above mate good advice to go for a bit thicker

 

[Gazzer]

floor board is 18mm

 

[essex_lee]

So if I wanted to I can lay 18mm ply, I know you suggest thicker ;-)

 

[Gazzer]

Yes but make sure you strengthen the floor with noggins. You really need a solid floor for a good job.

 

[essex_lee]

What's the difference between hardwood and softwood ply apart from the £30