T&G flooring, movement, porcelin tiles advice pls

[Matthew77]

Hi All.

I went to look at a job a few weeks ago to tile a upstairs bathroom floor with 10mm thick porcelin tiles onto wooden tongue & groove flooring, supplied is BAL flexi adhesive. The builder there was going to ply ontop of the T&G with 6mm ply & I expressed a concern about the floor still flexing, I suggested a cement based board instead of ply.
I went back today and the builder is also worried about the floor flexing so has asked me to advise him some products that would be suitable as he want to garantee the work. He is keen to keep the height difference between the landing floor and bathroom floor to a minumum(both are T&G).
The joists are 6" by 2" & are spaced at 400mm centres & the T&G is 22mm thick by 110mm wide. The T&G can be removed if need be.
What would be the best way to make sure the floor is solid enough to tile onto?
Would 10mm backer board be enough on its own or on top of the T&G?
Any advice on this would be greatly apreciated.
thanks Matthew

 

[GazLC81]

Never used backer boards but would think that 6mm stuck down with a single part flex and then screwed down should be fine.

Someone else will be along soon to give you better advice!

Gaz

 

[grumpygrouter]

How big is the floor? This will have a bearing on rigidity.

Grumpy

 

[Matthew77]

How big is the floor? This will have a bearing on rigidity.

Grumpy

Hi Grumpy.

it's about 3M by 2M so shouldn't be too flexi also some of the bathroom sits on the supporting wall below.

 

[Turkish]

Having read many threads on this subject I would say screw down existing floor then put down adhesive and 6mm hardibacker screwed as well, keeps the floor level to a minimum too. Hopefully someone with more experience will back me up otherwise i will have learnt something else!

Turkish

 

[GazTech]

Having read many threads on this subject I would say screw down existing floor then put down adhesive and 6mm hardibacker screwed as well, keeps the floor level to a minimum too. Hopefully someone with more experience will back me up otherwise i will have learnt something else!

Turkish

I agree, small floor little movement, if you want to be certain of job, use 2 part flexi onto 6mm boards, no need to bed boards on any adhesive then......Gaz

 

[Matthew77]

Thanks alot for your replies everyone.

Great advice as always