Glue(?) for Thin Patio Slabs

[JAW911]

I have a concrete area about 5 sqm outside our back door from which steps lead down to our patio. The patio is slabbed, the concrete and steps are bare. I have found slim slabs which can be laid on this concrete area and the backdoor can still swing open but won't have sufficient clearance for a bed of mortar. It is a smooth concrete base - does anyone know of a concrete/cement glue that will hold the slabs in place on the concrete are and steps please?

 

[sammy.se]

I would probably use CT1 in that scenario. It's very good.

 

[paulrbarnard]

I have a concrete area about 5 sqm outside our back door from which steps lead down to our patio. The patio is slabbed, the concrete and steps are bare. I have found slim slabs which can be laid on this concrete area and the backdoor can still swing open but won't have sufficient clearance for a bed of mortar. It is a smooth concrete base - does anyone know of a concrete/cement glue that will hold the slabs in place on the concrete are and steps please?

Would floor tile adhesive do the trick?

 

[Jameshow]

Ebt is much the same stuff but cheaper than m5200 and slkaflix 291 etc etc.

 

[Bingy man]

Your 1st problem will be how level is the concrete slab the second is if these are 20mm stone or porcelain slabs then they req a 30 mm bed of mortar to lay them with a slight fall away from the building. I m not saying the adhesives mentioned won’t work short term but tbh I can’t see that approach lasting very long . What size are the slabs and how many ? As ct1 is around £13 tube how many will you need for 5 sq meters . Personally if raising the door is not an option then I’d be looking at sealing the concrete and using some type of bitumen similar to that used with parquet flooring. But it will mainly depend on how flat that concrete slab is and of course the size of the slabs - bigger they are the greater the potential problems .

 

[Jameshow]

Ebt is much the same stuff but cheaper than m5200 and slkaflix 291 etc etc.

Or what about laying them direct to floor screed or would they sink?!

 

[Agent_zed]

I may well be wrong but my take on it is that the main point of having something underneith the slab is not so much to stick them down but to ensure they are level and no part the slab casting is taking more weight than another part, which could cause a crack.

I'd look at doing a very thin screed of mortar ~5mm, or whatever you can get away with, and a thicker grout line - 25mm or so. Then the ones at the edge, which will likely take more uneven force as you step off them, stick them down with one of the builders adhesives like gripfill.

 

[Doug B]

Personally I’d be looking for a floor tile adhesive that is suitable for exterior locations & depending on the slabs you have one with a bonding agent in.
I would also lay the slabs using a solid bed trowel to ensure full adhesion over the entire bottom surface of the slabs.
I have done quite a few open balconies like this without any problems.