floor construction

**piehead** · 10-01-2010

some advice please anyone. starting a kitchen/utility/conservatory tomorrow with approx 50m2 of tiling. what i am concerned about is the floor consruction in the kitchen. at present there is karndean layed on 6mm ply but beneath that the original floor is a concrete sub floor with polystyrene insulation with chipboard on top. should i take the 6 mm ply up and replace with 12mm ply, the floor in the conservatory is concrete which also has karndean on it, thanks.

**salmonfisher** · 10-01-2010

sound like a floating floor in the kitchen, personally i wouldn't tile it

**Phil Hobson** · 10-01-2010

Originally Posted by salmonfisher

sound like a floating floor in the kitchen, personally i wouldn't tile it

I would be tempted to do more research, then contact your chosen adhesive tech dept. good luck

**Daz** · 10-01-2010

I agree with the above, you need to investigate further to identify if it is a floating floor, initially.

What size and type of tile are you proposing to install?
After removing the Karndean and ply, what deflection does the floor have?
Will you have any floor height issues with the conservatory once the Karndean has been lifted?

There are many other issues to consider before a decision can be made with regards to the prep work and, more importantly, whether the floor should / could be tiled.

doug boardley · 10-01-2010

this one could end in tears I'm afraid, floating floor (by the sound of it)

**Dave** · 10-01-2010

beneath that the original floor is a concrete sub floor with polystyrene insulation with chipboard on top

Speaks for it's self....

For any adhesive manufacturer to give a guarentee the floor will need to have Zero deflection.

I have not come across a floating floor that has Zero deflection.... you need to be very careful is my advice..

**piehead** · 11-01-2010

thanks for all your replies, got me worried now. it is definitly a floating floor took the ply and karndean up today. the tiles the customer has bought are 450mm by 450mm and there will be a height issue with the conservatory by time the ply has gone down in the kitchen also when you say deflection in the floor could you explain, thanks.

**Phil Hobson** · 11-01-2010

Deflection basicaly, is movement up/down, spring in floor. As opposed to lateral movement side to side. Mainly caused by expansion.

**Daz** · 11-01-2010

Tiling a floating floor is always going to be risky, as everyone has advised above.

The only consoling thought that I can offer, is that depending on the area that is floating you may be able to overboard with "No more ply" (glued and screwed at 150 mm centres). The no more ply will act as a decoupling membrane and could help with any deflection (bounce) that you may be experiencing. As it is only 6mm thick you may not have too much of a height issue.

Make sure that you leave expansion gaps where the floating floor meets the screed, otherwise you will be asking for more trouble.

Good luck and remember to advise the customer that tiling this floor is riddled with risk.