cement based adhesive

Hi I'm looking for some opinions on using cement based adhesive on gypsum plastered (skimmed) drywall? I'm doing my first paid tiling job (for a family member) she got all the material the supplier knew where the tile was to be fitted (plastered drywall) he supplied a cement based powdered adhesive It says on the bag "not to be used on gypsum based plaster" I asked him about this and he said its fine to use it he has sold tons of the stuff and never had a problem. My sister in law (the client) is happy enough to use it she says he should know what he is talking about, as it is his job. To make things worse there is a shower that is to be tiled and the substrate in the shower area is skimmed plasterboard (he says it is perfect for this as it is a flexible adhesive). I want to use ready mixed adhesive but am a bit unsure because the walls are studded walls not solid block walls and they will move a little. The supplier thinks I'm a donkey and my client thinks I'm over reacting. But it says on the bag it's not suitable. And I have researched it on the web and found something about some reaction between cement and gypsum. Should I just do the job with what he supplied and keep my opinions to myself?

Reply to
william
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I guess thats how easy it is to sell something to some folk.

if only that translated into reality. It should, but doesnt. Especially when it comes to building.

good lord, worst option for that. (Apart from dried porridge.) Plaster and cement react chemically if they get wet, and the result is they come apart. You dont use cement on plaster.

but not for the reason you think.

is your client skilled or experienced in the business? Client naivety is normal.

indeed... what does that tell you?

Your call - seems daft to me though to do a job for a family member that all falls off in 6 months.

NT

Reply to
N. Thornton

Hmm. It's normally much more expensive than the correct stuff - so perhaps that accounts for him being so keen to sell it?

Reply to
Dave Plowman (News)

Can you get the phone no. of the manufacturer from the bag or look it up?

Or this might give an answer:

more leads:

cheers, Pete.

Reply to
Pete C

In message , william writes

I'm not an expert at tiling but I've found that if you first seal the surface with PVA then use the pre-mixed Unibond combined grout/adhesive from B&Q (and no doubt many other places) then the tiles will stick to

*anything*.

I've tiled on raw plaster, old tiles and wood without a single tile coming loose. Good trick is to make sure you leave a gap at corners and fill that with mastic so if your walls shift slightly it doesn't squeeze the tiles off.

The odd thing is that when I buy tiles the tile shop always tries to sell me powder adhesives. They say that the pre-mixed stuff isn't any good as it "slumps". Never had any problems with it myself though.

Reply to
Sapient Fridge

Nothing is going to work well if the plaster/plasterboard gets wet. There are plenty of adhesives that will work on gypsum plaster, but if you get water in behind the grout, the tiles will ping off and the plaster will degrade.

I'd probably use something Like Ardu-Flex 6001 or BAL White Star, although it would still be better to replace the plaster background with something better.

If you don't replace the plasterboard with something waterproof, ensure you do the tiling job thoroughly. Use an adhesive suitable for swimming pools such as those mentioned above. Ensure complete coverage. This is not a time for dab and dot, you need 100% fill between tile and plaster. Remove an occasional tile during fitting to ensure that all ridges were compressed flat.

Pay very careful attention to grouting. Use a flexible grout such as ArduFlex FL/FS to reduce the chances of cracking. Keep the grout lines narrow. Seal the grout using Lithofin StainStop (KF or MN, probably KF for the types likely to be used in a shower). This will also stop the grout going mouldy and will encourage water to bead and run off, rather than penetrate the grout. You may wish to apply to the tiles as well as the grout lines, depending on the level of glaze. Use silicone sealant for internal corners of walls.

Christian.

Reply to
Christian McArdle

I've been using white cement adhesive for kitchen and bathroom, and they just fall off again. In fact when I cemented onto pva'd wood they didnt stick at all, just lifted off when dry. Dont nkow what kind of adhesive to choose, but obviously need something that works.

NT

Reply to
N. Thornton

Ardicol D20 claims to stick to stable timber boards such as plywood. Although intended for floor tiles, rather than wall, I'd be tempted to try ArduFlex 7001 Timber System with Ardion 51 primer, although it doesn't claim compatibility with walls...

Christian.

Reply to
Christian McArdle

I've used the white ready mixed stuff almost everywhere. Including a shower cubical made of plasterboard. And the outside loo. Never had a tile fall off yet.

Reply to
Dave Plowman (News)

did you tile kitchen and bathroom with adhesive from the same bag/batch of adhesive? if the bag is open and left around it seems to go off. when it sets it just turns to dust(like sand). on the bal website it says not to pva the surface of the plywood you are going to tile just seal/prime the edges and back.

Reply to
william

"Dave Plowman & christian McArdle replied...

thank you both, am going to investigate supplies.

NT

Reply to
N. Thornton

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