what depth to allow for quarry tiles on mortar over a slab?

[mnemonix]

Hi there,

I'm hoping to lay quarry tiles directly on to my new slab in the kitchen, so as I'm now setting out the level for the slab how much should I allow for the finish so I'm level with the floor in the rest of the house?

Is this the best approach to finishing the slab with quarry tiles, avoiding a screed? Is the mortar bed enough to make up any variation in the slab if I'm careful? Might a thin self levelling screed over the slab be useful?

Cheers.

 

[Richard C]

Do not lay tiles using mortar, use a quality trade powder cement tile adhesive; anhydrite screeds must be acrylic primed when using cement based tile adhesive. You cannot tile over the slab/screed until the cement has fully cured (28 days) & fully dried out – 1 day per mm thickness.

Allow the thickness of the quarry tiles + 4mm – 6mm for a thick solid bed adhesive. You should not lay a conventional sand/cement screed less than 50mm thick, there is a very good chance it will fail; alternatives are to use an SLC or bonded screed. You need as flat a tile base as possible or it will be all over the place & look terrible; the slab may not be good enough.

 

[simonjay]

Hi there,

I'm hoping to lay quarry tiles directly on to my new slab in the kitchen, so as I'm now setting out the level for the slab how much should I allow for the finish so I'm level with the floor in the rest of the house?

Is this the best approach to finishing the slab with quarry tiles, avoiding a screed? Is the mortar bed enough to make up any variation in the slab if I'm careful? Might a thin self levelling screed over the slab be useful?

Cheers.

They used to do it with mortar, so it must work. Also, slate floors are often layed this way, where the slate can vary from 10mm to 30mm in depth (unless you get the calibrated stuff). The kitchen floor I dug up had about 50mm mortar with the quarry tiles pressed into it. You could add some SBR or PVA for extra adhesion, and make sure the tiles are damp to not suck the water out.

However, these days a screed would often go down anyway, then normal tile adhesive. If you are doing it yourself and not a good screeder, you may end up with a better result laying over mortar with a spirit level. However, there can be problems with adhesion when using mortar.

Simon.

 

[mnemonix]

Thanks for the replies.

I'm using a laser level and battens on the wall to set the top of my slab so I'm reasonably confident it will be level and at the right height.

With that in mind I figure a thin self leveling screed will be the way to go to even out any iregularities and provide a good surface to fx the quarry tiles to, then a thick solid bed adhesive as recommended above.

5mm self levelling screed
5mm adhesive bed
8.5mm quarry tiles