slate floor lifting?

[tactile]

2 problems
i have priced up a kitchen floor which a customer had laid 4 years ago.
concrete floor with natural slate tiles.
there are 2 large sections which have lifted,but no obvious reason why!
the grout is cracking round alot of the tiles and the few tiles that have lifted look like the adhesive hasnt stuck to them, although it has stuck to the floor quite well.
i was wondering if adhesive doesnt stick to unsealed slate. as the customer said she sealed them herself after the floor was down?
also would you still use a flexible adhesive on slate even though its a concrete floor? or do you think the tiler has just used very cheap materials? or not primed the floor first?
i just want to make sure the same thing doesnt happen to me when i refit the loose tiles!

i also have my first curved wall to tile in 2 weeks time!
any tips would be gratefull!

[brian c]

The original slate tiles should maybe have been cleaned with fresh water to get rid of the dust that forms on them when they are cut at source and the floor may also may not have been dust free at the onset.I would use a flexi rapid set and flexi grout for this imo.

One of the more experienced tilers will need to help you with the curved wall m8,sorry never tiled one before .

[whitebeam]

The adhesive could have been to dry and has'nt adhered to the tile or the tile had dust on the back and was'nt wiped off before laying, Four years is a fair time for it to happen though

[Oli]

2 problems
also would you still use a flexible adhesive on slate even though its a concrete floor?

You need to use a flexible adhesive on slate mate, normal cement based adhesive wont bond to the tile well if at all. The rubber addetive helps with the grip to the tile as well as the flexibility.

In terms of the lifting, what's the substrate mate?

[Dave]

You need to use a flexible adhesive on slate mate, normal cement based adhesive wont bond to the tile well if at all. The rubber addetive helps with the grip to the tile as well as the flexibility.

In terms of the lifting, what's the substrate mate?

Errr...it does Oli........no probs.......the slate just needs a wipe with a damp sponge before laying.....back buttering also helps to get a solid bed on un-graded slate...

[Oli]

Yep my bad dave, for some reason I'd read the post and got it into my head, that he was using an acrylic based addy, it's been a long day, i think i need to go to bed, by eyes are getting blury from rubbing them to stay awake

I even typed cement based addy, and it still didnt register lol.

[Sir Ramic]

You need to use a flexible adhesive on slate mate, normal cement based adhesive wont bond to the tile well if at all. The rubber addetive helps with the grip to the tile as well as the flexibility.

In terms of the lifting, what's the substrate mate?

You sure mate, Slate has been used for years as a floor covering. Long before flexible adhesive arrived.

I would think the problem is as others have said, you need to clean the slate before fixing.

[Oli]

You sure mate, Slate has been used for years as a floor covering. Long before flexible adhesive arrived.

I would think the problem is as others have said, you need to clean the slate before fixing.

No mate, as above, brains not working tonight. Think ill go to bed and try again tomorow.....

[Sir Ramic]

No mate, as above, brains not working tonight. Think ill go to bed and try again tomorow.....

No problem i have a few days like that myself.

[alex1963]

you know its funny but back in the 80's when slate was all the rage here we did 1000's'of m2s of th stuff and all we did was sort the grades ,then butter the backs with basic cement based glue mixed with a bit of latex and throw the tiles down,no primer or washing tiles ,and in all those years we never had a tile lift or a floor fail !