Slate over wet ufh

The Legend; Phil Hobson RIP · Sep 28, 2011

Hi peeps, just a question and would appreciate any input, I am pricing a un-calibrated opus pattern slate floor. This is over a wet ufh system, my concerns are , would you think slate, given it's quite fragile nature would stand up to the heating / cooling cycle without shelling / flaking etc.? I have convinced the client to go with a de-coupling membrane.

As I have never laid slate over ufh, although I have laid loads of slate, I would like some other opinions. The other nagging question is, the slate is very bad for shape, riven finish both sides. I have pointed out to the client that even after grading the tiles and lots of bedding up etc, there will be some lippage. To which she replied " I don't want any lips".

The slate is from Tile Giant, I asked her to go back to the showroom and check out the display, telling her that the display tiles would have been chosen for their uniformity, even so there are 4mm/5mm lips on the display. Having returned to the TG store she is adamant she wants to use this tile.

As the pattern is opus ( five sizes) I am governed by the pattern for joint size. Normally with slate I would give 10mm/15mm joint, but in this case I am limited to 4mm/5mm joint. Any thoughts?

Thanks, Phil.

DHTiling · Sep 28, 2011

Hi Phil... it will take a lot more heat than that floor can throw at it to make slate shell/blow under heat stress IMO..

As for lippage.. she is avin a laff.. 🙂.. you will be edge chipping for ages to get it lip free.. :lol:

The Legend; Phil Hobson RIP · Sep 28, 2011

Cheers Dave, I thought slate should be OK with ufh, just spoke to an old apprentice of mine yesterday, and he said he thought there might be issues, just got me thinking, I should know better than listen to old apprentices:lol:

DHTiling · Sep 28, 2011

If you think that slate gets used on Hearths etc and roofs and no shelling with those..

I have used it over electric ufh quite a few times and nowt.. but wet doesn't really get that hot or you would not be able to walk on it.. lol..

Rich · Sep 28, 2011

Iv done loads of slate over UFH over the last year, it really deems to be in fashion at the moment, I haven't had a problem so far *Rich crosses his fingers*

I would be more worries about the lipage. Why in the name of everything holy would you choose un-calibrated slate if you wanted a lip free, flat floor?
Dont you just love customers?

Time's Ran Out · Sep 28, 2011

I had a conversation about a very similar issue with an 'old' mate earlier this evening (he actually woke me up - well it was 7-30pm!).
Sometimes when I estimate/discuss tiling with a customer I tend to give too many 'pointers' as to what they should expect from a job, as though I'am selling the fact that they should have the job done properly. And I ask myself 'am I trying to justify my price?
But the answer always comes back - give them all the information they need and hope they DO want the job done properly.
The job we are on is exactly this - Slate over UFH - and as we did the same 10 years ago for the same client (in a different house) we've never encountered any problems.
Another part of this job is also Opus pattern Travertine as a frieze border and into other rooms. Your size problem for joint width is an issue and we are having to trim some of the small square pieces to keep an even joint.
Many years ago I used to advertise work to a Showroom standard, but now most of them seem to be very poor and at times I wonder how people can be enticed to buy some of the displays on view.
Good luck with the pricing.