Floor preparation

[SergeTiler]

Conservatory floor: remove old tiles, put new ones, app. 15 sq.m. Old tiles have cracks which may indicate floor movement. Would levelling compound (backer boards (?)) plus uncoupling membrane make it?

 

[eddcottee]

Sorry for the slow resposne. Is it a timber sub floor?

 

[SergeTiler]

Sorry for the slow resposne. Is it a timber sub floor?

YES. chipboards.

 

[eddcottee]

All depends how much bounce there is then. The chipboard floor might need lifting and extra supports putting into the frame. Or you may get away with simply overboarding with hardiebacker. You'll have to judge it for yourself as to how much movement there is. You can read about "deflection tests" online. Essentially you need there to be no visual movement in the floor if you jump on it.

If no underfloor heating, I wouldn't bother with an uncoupling mat personally. The problem in that floor is bounce and the mat won't help with that.

The backerboards should hopefully give the floor the rigidity it needs.

 

[SergeTiler]

All depends how much bounce there is then. The chipboard floor might need lifting and extra supports putting into the frame. Or you may get away with simply overboarding with hardiebacker. You'll have to judge it for yourself as to how much movement there is. You can read about "deflection tests" online. Essentially you need there to be no visual movement in the floor if you jump on it.

If no underfloor heating, I wouldn't bother with an uncoupling mat personally. The problem in that floor is bounce and the mat won't help with that.

The backerboards should hopefully give the floor the rigidity it needs.

Thank you very much. tried testing it for deflection, yet this was not, frankly, quite conclusive. However, there are some engineering calculations and seemed within tolerances, though at the limit.

In fact, I did exactly as you said: I added hardierbacker boards (12 mm, rather than 6 mm). I also added a layer of mapei membrane. Alternative would have been, as you said, to pick up the floor and prop up the joists, and that would have been a completely different project.

 

[eddcottee]

With the 12mm hardie down, I'm sure it will be fine mate 👍