Help with the right adhesive and trowel

[mordzy]

Hi All. Ive done some research which has confused me more than when I started reading. So thought id post for some advice.

I have a poured concrete screed floor with UFH, its been down 18 months with UFH on low. The surface has been sanded as it had a sheen when it first cured. Im wanting to tile it (have tiled walls before) but wanted to do it right. As such ive purchased the tiles and membrane but have a couple of questions.

1.What adhesive should I be using. Ive looked at Mapei Keraquick Wall & Floor Rapid-Set Flexible and Mapei Rapid-Set Flex Wall & Floor Adhesive. not sure what the difference is other than the price.

3. Ive bought durabase anti-fracture membrane. Can I use the same adhesive as above?

4. My tiles are 150x600mm food effect porcelain. what size trowel notch should I be using?

5. The screed is level, smooth, clean and dry. Ive washed it and vac'd it, do I need to prime it or will I be ok?



Thanks for the advice.

 

[Swwils]

What type of screed is it

 

[mordzy]

Poured concrete

 

[Mr Chibs]

If it was a liquid screed, it should be primed first with ‘primer g’. As some of the tile adhesives don’t take well to liquid screeds.

I used semi rapid, but as I was doing it myself, I was slow.

my tiles are 600x400 and I used the largest notched trowel, think it was 20mm x 10mm tall.

I too used durabase mat, as I have ufh.

I also used (first time) the levelling wedges (vitrex) big of a faff, but excellent finish, tiles went down really nicely and flat. I would lay a floor without them now.

good luck and Merry Christmas.

 

[mordzy]

Thanks for the advise Mr Chibbs.

Ive done some test and opted for the following

6mm square notch trowel that collapses to 3mm for the matting

Mapie primer G

I tried both adhesives in a test spot and were solid so went with cheaper one. Mapei Rapid-Set Flex Wall & Floor Adhesive

used the same adhesive for matting as well as tiles.

Did a test spot for the tiles, used same trowel and back buttered. Took tile off and had collapsed niclely with about 4mm of adhesive layer. since my tiles are quite narrow (parquet flooring style) I maybe ok with the smaller notch.

Ive used the self levelling stuff before but to be honest I found them annoying and still had lippage... could have been the tile size and floor. because these are narrow im going to just use a spirit level etc.

my job for tomorrow/Boxing Day since ive got covid so the kids cant come

Cheers and happy xmas.

 

[tilerman]

If the screed is an anhydrite screed the surface laitance MUST be ground off before you do anything else. If you do not remove this layer, you are asking for trouble. Ask the company who done your pour if they do this service, many do.