Floor tiles on top of insulation

[Polstar]

I have specified this as an upgrade to a garage floor (for conversion) and the client has been told by a tiler that he cannot lay floor tiles on top as there is too much deflection...

Tyvek Control layer
70mm Kingspan K3
Visqueen
Sand blinding
Existing garage slab.

I would have thought that this is rigid enough to lay floor tiles, any help would be appreciated..

Eddy

 

[tpt]

I'd say the tiler is right. What is specified to go on top of the tyvek? and whats the use of the room after the conversion?

 

[Polstar]

I beleive the builder has laid plywood - not sure what thickness.
The room is going to be a dining area through from the kitchen.
I was thinking of suggesting to cut out strips of insulation and fix battens/joists to garage slab and then board over with 18mm marine ply.
Will Ditra be any good in this sort of situation?

Thanks very much...

Eddy

 

[tpt]

I'm assuming the floor isn't laid yet so the tiler probably just warning about deflection - in truth it shouldn't have a lot as long as the kingspan is well supported.

18mm marine ply will be fine and is a good choice, but you'll need to stop the boards from moving apart. Basically its a floating floor - it is possible to tile it BUT....

Our advice is usually to overboard the ply with 9 or 12mm no more ply (cement backer board). glue and screw this down across the joints of the ply and then fix to that with at least an S1 adhesive. OR you could double ply it and cross board the ply (and glue\screw it)

Granfix's advice (adhesive manufacturer) is that as long as the deflection is minimal, you should board it with a tongue and groove flooring panel - gluing the T&G to stop the boards seperating, lightly sand and acrylic bond the board (neat acrylic - 1 coat) and then tile it with ultimate flex, followed by maxigrout with flexi additive. They will back this with a 25yr guarantee but the issue i have with this is that if it cracks then deflection will be blamed - hence our overboard advice.

Ditra matting - no it wont help with deflection at all, its for lateral movement.

 

[Polstar]

Thanmks very much for yout time and help, i will take this to me client....