Help Please UFH - Mosaic Tiles

[newpark7]

Hi everyone I haven't posted for a while but need advice please.

I have been asked to quote on installing customers own UFH heat mat (B&Q) and tiling the floor with Mosaics. As I have not had much to do with Mosacis before and never on the floor. My questions are: -

1) Can you use Mosaics for floor tiling and are they compatible with UFH?
2) Would it be best to lay a latex compound over the matt before tiling? the customer has laid backer boards over a timber floor (upstairs En-suite).
3) Any tips on laying Mosaics on to floor Mosaic trowel or normal? recommended adhesive etc?

Any help greatly appreciated as always.

Newpark7

[david campbell]

mosaics will be fine for the floor but you will need to self level over the ufh and make sure it is absolutely perfectly flat,or it will show up!
depending on the mosaic thickness i would use a trowel a couple of mm shallower,and a good flexible or mosaic fix adhesive

[newpark7]

Thanks David most appreciated.

[david campbell]

no probs

[Rich]

Are they stone, ceramic or glass mosaics? I have come across glass mosaics that are not suitable for floors, just be aware. As David said above, it is very important to get the floor totally flat before tiling so slc is a must over the heat mat. Apart from that it is really just a case of taking your time with it, might be worth thinking about using a standard setting adhesive rather than a rapid.

[newpark7]

Just trying to find out tile material from customer - thanks for the advice, what SLC do you use/recommend ?

[Rich]

It depends on what adhesive you will be using, try to use the same manufacturer. Best bet would be to ask when you get the adhesive what slc they would suggest, make sure you tell them that it is for ufh and will be tiled with mosaics.

If the mosaics turn out to be glass, Id get the number of the supplier from the customer and give them a ring just make sure that they are suitable, never hurts to make sure.

[newpark7]

Forgot to ask - will the backer boards need priming/sealing? would Bal APD be suitable if required? as I have some in stock.

[whitebeam]

Should'nt need to prime backer boards

[newpark7]

Should'nt need to prime backer boards

Thank you for that.

[jay]

i take it the floor is deflection free (no bounce)

[newpark7]

Hi Jay

It seems pretty good - thanks.

[jay]

and the customer has installed 6mm cement sheet with lots of screws with no voids under it as once you tile it you wear it be careful

[newpark7]

Hmmm - good point I didn't notice that many fixings in place & have no way of telling if any voids etc I will have to have a really good look before quoting I thinks.

[jay]

voids will show up when you walk on it floor will move under foot and yes needs a lot of screws about 120 to 130 per 1.8 x.9 sheet or around 150mm cantres more around edges good luck

[doug boardley]

when you come to laying your mosaics, use a grout float to pad them down to ensure a good contact with your adhesive.

[Rich]

Just to add to the above, the backer boards should have been glued down aswell as screwed, the glue/adhesive will fill any voids under the boards. I come across LOTS of customers (usually builders) that screw the boards down as if they are laying ply and dont look at the fitting instructions.

If they have used glue/adhesive and the boards are screwed down plenty you should be fine

[newpark7]

Ok - thanks I will check with customer, I certainly don't recall seeing any evidence of adhesive. Would you normally use tile adhesive underneath? I think all materials they have used so far have come from B&Q!

[Rich]

Most brands say use a single part tile adhesive but others sell an expanding glue that you apply to the boards before you lay them. I dont know what make B&Q sell so couldnt say, I would have thought that there would be fitting instructions with the boards?

[jay]

the adh is only to fill in hollows or voids in floor to keep it flat and solid the screws hold it solid