Cleaning slate before sealing-grouting -sealing

[jmhole]

Hi, I'm laying riven Slate on to screed floor with wet underfloor heating, I have finished two rooms and want to seal and grout them whats the most efficient way to clean the tiles effectively so that I have no problems with sealer?

Thanks

 

[doug boardley]

warm, clean water imo, then wait until your slate is completely dry and haze free. I use LTP mattstone as an impregnating sealer, do one coat before grouting, and then another coat after your grout has completely dried

 

[jmhole]

Thanks, Doug

Warm clean water it is then! loving the way the slate looks on the floor, want to get a room finished! it seems that from reading on here people dont like laying the riven slate? seems fine to me!

 

[doug boardley]

the problem with riven slate is the lippage you get from them being uneven thickness, bowed etc. If there's any obvious trip hazards with the lippage I'd get a sharp bolster and re-rive them in situ. This should be done prior to sealing

 

[jmhole]

Have been knocking any big lips off and being selective about what goes where! almost halfway through the job got to start the big room tomorrow do you need to take any precautions for expansion on a large area?

 

[diamondtiling]

How long has the screed been down and has the UFH been commissioned ?
What size is the larger room.

 

[jmhole]

The screed has been down for 10 weeks so plenty of curing time, the UFH is not connected up to boiler yet if that is what you mean by commissioned, but it is filled and pressured so any leaks would have been instantly known about.
The large room is about 48m2.

 

[diamondtiling]

The UFH must be brought up to maximum temperature very slowly and then returned down to cold again, failure to do this will result in the screed failing.

:20:

 

[jmhole]

Ok thanks, is it critical for that to be done before it is tiled, and fail in what way?

 

[diamondtiling]

It will fail because it has not been allowed to expand and contract with the heating up and cooling down. There are many threads on here where the floor has been tiled without the correct procedure being carried out.
It is critical that you do this.
Is there UFH in the rooms that you have tiled?