Waterproof membrane and Tiles

Good afternoon forumites,
<O:p</O:p
I have a question about waterproof membranes and tiling that I can't seem to find an answer on in existing posts. I am about to finish off our bathroom and have purchased a drum of Bondall Aquatite to waterproof the floor and walls of the shower area prior to tiling.
<O:p
Having read another post somewhere here I am following the suggestion that the membrane on the floor should go between the mortar and the tiles, rather than below the mortar to avoid the mortar taking in water should the tile adhesive fail. The walls are of a generic wet area panelling similar to Villaboard.
<O:p
I have queried Bondall in regards to an appropriate tile adhesive to which they have advised I should use a water based or cementitious adhesive.
<O:p
My concern is that I had reason to remove a portion of the membrane from the walls and found that it peeled off quite easily. I am now worried that if I lay the tiles over the membrane won’t that mean that the tiles are really only held to the wall lining by the membrane, which does not seem to have adequate adhesive strength?
<O:p
Or would it just be a matter of keying in the wall linings prior to painting on the membrane. And what about the floor?
<O:p
Thanks to anyone who has knowledge on this.

I never tried to pull any membrane off but I would have thought is should stick pretty well. Did you prime your cement sheet prior to the membrane so that any dust was stuck down?

Thanks for the reply OBBob. You're right on the money there - as usual I rushed headlong into the job and painted it straight on without really thinking it through too well.

I rang Bondall and they said that the membrane doesn't provide any chemical adhsion as such, but that a porous surface should provide a sufficient base for it to hang onto, and that there shouldn't be any problem to tile over this.

They didn't mention anything about priming - heres for my first stupid question but what sort of primer should i use for this?

Hi Yumbo

The priming idea was just what occured to me when you mentioned the lack of adhesion. I'm sure my mebrane, which was a diffierent brand said it had to be primed. Further, I have noticed (having done a few bathrooms now) that cement sheet products always seem to have a layer of dust on them. For that reason I always prime before tiling etc. just to make sure that dust is stuck down too.

I use a Davco product ... thinks it's call Ultraprime? It just looks like watered down PVA glue, which probably what it is ... at an inflated price!! You just brush it on and it doesn't take long to dry.

I guess it's a bit late for the membrane but it is worth is for the other tiling so that you don't have any issue with the adhesive sticking.