Hi, I am new to this forum, and maybe in the wrong one, I have been reading post in this forum, but would like an answer, please, to the above title.
My bathroom is only 2sq metres and the floor is asphalt over concrete, the asphalt does not go all the way under the old bath, just about 4inches, so I have two levels.
1, So, do I take the asphalt up, and if so what do I use on the concrete before putting down 400 x 330 ceramic floor tiles?
2, or do I leave the asphalt down, level off under the bath with old tiles or cement board, in which case what preperation and ahdesive do I use on top of ashphalt.
Thank you in advance for your replies.

hi sparky

Is your bathroom on the ground floor of your property?

Thanks
GRR

yes it is, it is a bungalow

Sparky

Level off the concrete section with Mapei Adesilex P4 (20mm max. each coat) or Granirapid (1omm each coat). Clean and degrease asphalt and fix tiles over both substrates with Granirapid

dock

When you say it is asphalt over concrete are you talking about proper asphalt (road base looking stuff) or is it just a black bitumenous coating over t to he concrete. Trying to get to the reason why it might be there. If bituminous coating it may be a DPM in which case it might be wrong to remove it without replacing it with something else.

In terms of tiling - concrete is more durable as a substrate and more dimensionally stable than asphalt so I would think it better for tiling

Ajax123, I think you are right, on closer inspection under the bath where there is no 'black stuff' I can see the damp course material coming out of the brick work and resting on the concrete for about 1 inch. So I think we can assume the 'black stuff' is the damp course floor, they just did not carry it on under the bath; don't know why though.
I assumed it was asphalt because it is brittle, I thought bitumen was soft/plyable.

how old is your house sparky?

does the black stuff look like this?

Its nearly 40 years old, no more anyhow.
Cannot really see much detail in the photo, sorry, I could say it was like it, but I might be wrong.
I broke a piece off from the edge under the bath with a floorboard chisel and it just snapped clean off, leving no residue on the concrete. It was about 10 to 15mm thick.
We originaly had vinyle tiles down, and they stuck very well ( for 30 years) and when I have been plastering the walls, last week, the plaster that landed on the floor (ha ha), stuck like glue, its been a pain to get off.

well my house is only 6 years old and apparently, Barratts claim that no damp proof membrane was put down in the house prior to it being sold. and the black stuff that's throughtout the ground floor of my house is as you describe - snapped clean off at edges, leaves no residue on the concrete underneath and is about 10-15mm thick. Oh and it's solid as a rock, shiny in places, can score lines in it but can't dig into it without putting my back out and it's relatively flat except for the odd nipple here and there

I have twice laid floor tiles over the black dpm stuff and I have never bothered to self level or overboard first. I've just simply primed and then put the adhesive straight on top.

Other members might have other views, opinions and ideas, and it's worth waiting for a few more people to give their input, as I'm not a professional tiler.

GRR

dock, thanks for that info,
I am getting all my tiles and Mapei wall adhesive from Tile Giant in my area. Will they be able to get the Mapei Adesilex P4 and Granirapid for me do you think?

GirlRacerRed, can you tell me what primer you used please. Thanks

Originally Posted by sparky

GirlRacerRed, can you tell me what primer you used please. Thanks

I used BAL primer for the kitchen and hallway floor jobs. if you visit your nearest Tile Giant store, they should be able to advise which is the most suitable primer for your job.