Floorboards and plywood

[Anna79]

Hi all hoping to get some advice.

We want to lay quite abit of tiling downstairs on what is currently floorboards.

The builder has put down 18mm plywood on the existing floorboards and is planning to put down a mesh with a layer of flexible adhesive. Then the tiles will be laid with another layer of adhesive on that. The mesh is supposed to stop cracking of the tiles due to movement.

Whilst discussing with a friend they told us that their builder had told them that the only way to avoid cracking is to use a product like ditra mat as anything else will shift and crack.

Can anyone advise?

Much appreciated.

 

[Time's Ran Out]

Every job is different and little choices like tile type can change a specification.
However using Ditra will certainly be a better method of preparation.

 

[Anna79]

Every job is different and little choices like tile type can change a specification.
However using Ditra will certainly be a better method of preparation.

Thanks a lot.

Have been reading up a bit and have found that the ply should be laid staggered and with a small gap for movement. How important is leaving a 1mm gap between the plyboards and how important is it to lay them staggered if using ditra matting? I dont believe ours has been laid in this fashion.

 

[Time's Ran Out]

Your right, using Ditra overcomes the plywood layout. As for the gap around the plywood you will most likely find it will shrink as it dries in situ.

 

[Anna79]

Your right, using Ditra overcomes the plywood layout. As for the gap around the plywood you will most likely find it will shrink as it dries in situ.

One part of the floor is old mosaic tiling on a thin layer of concrete and on compacted earth. A surveyor advised to excavate a little, damproof and lay some fresh concrete. They are going to lay approx 10cm with mesh. Should that also be covered with Ditra mat or would the concrete and mesh do the job for tiling?