New Cemfloor Liquid Screed

[Timmy Mcguire]

Hi There,

Just wondering if anybody has had any experience tiling onto cemfloor liquid screed. The screeder is telling me that its a new cement based screed and that it doesn't need to be sanded or primed before putting the tile down? The surface is smooth and rock solid but I've always sanded and primed all liquid screeds before I put tiles down? Any advice would be greatly appreciated.

 

[Ajax123]

Nightmare.... the screed, as with every other screed should be sanded to remove and surface contamination. There may not appear to be a laitance in the same way as you see with anhydride but there will be aling with other construction contamination. Sanding is a simple requiremen of the contract flooring association guidelines and the tiling association guide. I've had loads of people say it does not need sanding but if you look at the CSTM certificate it clearly says requires surface abrasion prior to bonding floor coverings. I had one guy tell me the CSTM doesnt apply the UK.... hang on says I... why not... because we use different during agents here.... stick it in writing along with the warranty for the floor coverings says I... no response...

 

[Timmy Mcguire]

Thanks for your reply Ajax. Ive been going back and forth with the screeder who installed the floor and he is adamant that no surface sanding is required it just needs to be cleaned to remove any building dirt and dust. I am cautious to tile onto the screed without further guarantees (i.e. he'll take all responsibility). Has anyone tiled onto cemfloor without sanding it first? Has anyone had/heard of any problems with this screed?

 

[Ajax123]

Is he going to guarantee the tiles if you don't sand it...

 

[Timmy Mcguire]

No not yet but that's what I'm asking him to do before I lay the tiles on the un-sanded screed. He says BAL and Mapei have carried out trials with their adhesives and they have approved using their adhesives on cemfloor without sanding it?

 

[Tile Shop]

Then if he doesn't guarantee it, get it in writing from both BAL and Mapei that they've tested it and which of their adhesives they recommend along will an installation procedure.

If they can't produce that for you, i'd be looking for a tried and tested alternative screed.

 

[Timmy Mcguire]

Ive asked for a copy of the test results from BAL and Mapei along with an installation procedure and hes to get back to me with those. The floor is in perfect condition with no cracks and is perfectly smooth the surface is rock solid with no dust and it is even difficult to scratch with a nail. I'm just wary of tiling to it without sanding as Ive always been told that this is a must with all liquid screeds!!!

 

[Dumbo]

Just phone bal technical . Take him out of the loop .

 

[Italy]

Thanks for your reply Ajax. Ive been going back and forth with the screeder who installed the floor and he is adamant that no surface sanding is required it just needs to be cleaned to remove any building dirt and dust. I am cautious to tile onto the screed without further guarantees (i.e. he'll take all responsibility). Has anyone tiled onto cemfloor without sanding it first? Has anyone had/heard of any problems with this screed?

Here in Italy, all liquid screeds,
they are based on cement, not anhydride.
care must be taken if there are stains
of light color in the screed.
those stains should be scratched.
are water residues.
I scrape only those points, very evident when
you put the primer.
in any case, always the primer before laying.

 

[Timmy Mcguire]

I phoned the BAL technical guys and they've said that yes they have tested cemfloor screed. They recommend cleaning the surface of the screed to remove all dust and building residue and then applying one of their cement based adhesives directly to the surface. He said there is no need for sanding if the surface of the screed is in good condition.

 

[Dumbo]

I phoned the BAL technical guys and they've said that yes they have tested cemfloor screed. They recommend cleaning the surface of the screed to remove all dust and building residue and then applying one of their cement based adhesives directly to the surface. He said there is no need for sanding if the surface of the screed is in good condition.

Best option . Go straight the top and hear it straight from the horses mouth .

 

[Timmy Mcguire]

Ya exactly JCR. They said because its a cement based screed there is no need to sand it as the adhesives are also cement based; I guess its the same as for Sand:Cement screeds; just make sure the surface is in good nick and well cleaned.

 

[Ajax123]

I phoned the BAL technical guys and they've said that yes they have tested cemfloor screed. They recommend cleaning the surface of the screed to remove all dust and building residue and then applying one of their cement based adhesives directly to the surface. He said there is no need for sanding if the surface of the screed is in good condition.

And how do they recommend cleaning the surface? The usually accepted term is "lightly abrade"

 

[Ajax123]

I return to my previous comment. It is not BAL that will pick up the tab if it goes wrong...

 

[Dumbo]

And how do they recommend cleaning the surface? The usually accepted term is "lightly abrade"

If you're deliberately ambiguous if give you plenty of options to say what the tiler did wrong if it fails .