Tiling over paint?

[paul.c]

Hi,

Gonna start tiling bathroom on Saturday if possible. Its a new house and everywhere is off white in colour maybe light magnolia I think

.Im not sure if the walls are painted with emulsion or a mist coat. When I rub my hand on the wall it seems a bit powdery. Is it alright to till over the bath on this surface.

I have read lots of forums and different advice is given everywhere. How do I know its a mist coat? If it s emulsion do I need to remove it? The walls are not pastered but they are filled with Gyproc joint filler. Do I need to score it? If I remove the paint I feel that I will remove the plasterboards paper edge.

I have a bucket of evostick tanking system that I intend on using.

Whats the best way of approaching this?

I think it emulsion or mist-coat so my plan was no primer- first use tanking system- then fix tile straight on.

Others seem to think the best technique is to score with a wire brush, sand, prime, tank, tile? But all the comments ive read are not really new builds. Any tips on how to find out if its a mist coat. I really pride myself on good work so I want to do a good job.

cheers lads, Paul

[jay]

best to remove the paint

[paul.c]

cheers,

If im honest I was hoping you wouldnt say that!

whats the best way to remove this when theres no skim underneath?

[jay]

sand paper with caution or you could re board the area to be tiled

[whitebeam]

A mist coat is a thin coat of emulsion to seal new plaster, dry linning should be sealed with a sealer to even out the suction for any emulsion which is hardly used because most decorators are on a naff price and give a thick one coat of paint..

As above try to remove.

[paul.c]

OK, Il take the advice Il sand down to the paper.

Do I then need to apply primer on or can I just lash on the tanking system and tile away.

Also when I sand too far (bound to happen on one or two spots)and hit plasterboard, will the adhesive grip this or will the tanking system turn the dusty surface into a sound base for the adhesive?

cheers, even though your advise hurts

[Colour Republic]

It sounds like you have a mist coat. If it's rubbing off on your hands it's what is sometimes called a 'Builders Flat' which is a matt emulsion, not to be confused with a vinyl matt emulsion.

A matt emulsion is quite porous and can easily be washed off, what ever you can't wash off has taken hold of the plasterboard and is well bonded. If you wash off the chalky substance you can then prime the area with the apporiate sealer recommended with your adhesive.

[paul.c]

It sounds like you have a mist coat. If it's rubbing off on your hands it's what is sometimes called a 'Builders Flat' which is a matt emulsion, not to be confused with a vinyl matt emulsion.

A matt emulsion is quite porous and can easily be washed off, what ever you can't wash off has taken hold of the plasterboard and is well bonded. If you wash off the chalky substance you can then prime the area with the apporiate sealer recommended with your adhesive.

Thats what I was hoping. So would warm water and a sponge tell me better what im dealing with here. I literally lightly glide my fingertips along the wall and im left with white chalky powder on them. Do I need a primer with a waterprofing tanking system? Bog standard evostick stuff. Whats the best way? Prime-tank-adhesive-tile or tank-prime--adhesive-tile. surely I dont need both?

[silver]

Hi Paul,
painted walls.....after many different ways of trying..I have spent time with scour pad on the walls scrubbing it off with water....dry scraping and wire brushing...its really dependant on emulsion thats been used...walls being sealed before painting etc...
Straight on to board without skim is different
however....if you have any areas that are skimmed

what really works for me so far is......

Wet the walls with a sponge....working on a 1m area...........wet it....let it soak in...wet it again....even if it starts to appear on the sponge....wet the next 1m area.........take one of those long handled (about 300mm) extremely sharp bladed decorators scrapers......make a start....lightly scrape the wall.
I have found that once the water / soak is through....if it is going to come off...its very quick and easy to start to take off in skin like strips with the scraper....try not to "dig in" and keep the edge as sharp / acute to the surface as possible.

Part way through wet the next section again and so on......if you get to a bit thats a bit tough...wet it a bit more.

I used to dread taking off emulsion and I know that quotes in after mine would say it wasnt necessary !!!!....cuz they didnt want to do it...didnt care.....and they would take the job....now it has so far for many jobs been quick and easy this way...though the wall will get wet enough to need to dry out...so account for this.

If this fails then I would be roughing the surface, priming etc

Hope this helps
Degs