Plastering over tanking kit

[cecildasbo]

Hi all
I am in the process of finishing off our bathroom. At the moment I have got plasterboard dot and dabbed onto one of the walls. At one end we will have a shower cubicle that will take up half of the wall. This area has been tanked with the 'bal wp1 tanking kit' directly onto the plasterboard and will be tiled later. The tiling will stop where the end of the shower cubicle is and the rest of the wall is due to be skimmed, ready for painting. (My missus didn't want a fully tiled wall!)

I have a couple of questions. Our plasterer is coming in before the tiler. Will he be able to easily feather the skim so that there isn't a massive lip that the tiler will then have to deal with? Or is it better to get it tiled first then get the plasterer to skim up to the edge of the tiles? Also, to be on the safe side when I applied the tanking kit, I painted it a bit beyond where the shower cubicle/tiling will be. Will the plasterer struggle to be able to skim over this section? It's probably about 30 cm. In hindsight, should I have tanked only up to exactly where the shower ends?

I'm just now worried about the tanking being so waterproof that any skim will not key to the plasterboard.

Cheers

 

[Richard C]

Does your plasterer know your expecting him to plaster over a liquid tanking membrane? It might pay to warn him. If you know what your doing, you can plaster over practically anything with the correct prep, including tiles. I’m sure WP1 is no different but I’ve never tried it & it may need slurry coat priming in order for the plaster to bond properly. You could try giving BAL technical a ring (Tel: 01782 591120) to see what they say. You’d have been much better off using a waterproof tile backer board in wet areas, by the time you factor in the extra work & cost of tanking, there’s virtually no difference.

I always plaster non tiled areas first, wasting into the tiled area. If you’re tiling onto dot & dab plasterboard you should also provide additional mechanical fixings, especially with large format tiles or the whole lot could end up on the floor; what weight are your tiles?

I would also advise you read the Tiling Forum Sticky & Forum Archive posts before doing any more work or buying tiling materials, it could prevent you making disastrous & potentially expensive mistakes. It’s important to use only quality trade tilling materials of the correct type for your tiles & tile base; cheapo own brand & DIY stuff is mostly crap.

 

[cecildasbo]

Richard, thanks for the prompt reply. Very helpful. The plasterer has seen the job and the tanking was painted on at the time, but my wife spoke to him so not sure he was made aware of it. I will let him know.

I'll also call BAL, cheers for the number.

Don't think my tiles are particularly heavy, they are 30cmx30cm. We are getting a pro in to do the tiling so I would hope he gets he best stuff for the job!

Cheers

 

[Richard C]

Probably around 12-15 kg/sqm + 2-4 kg/sqm for addy, you would be advised to pop some fixings through into to the wall in the tiled area; tap the wall to find the adhesive dabs & drill/fix through those. Your tiler should be using a flexible powder cement addy for tiles that size not tub ready mix which will take an age to set & then sometimes it doesn’t. You must also acrylic prime plaster/plasterboard when using powder addy to avoid a reaction between gypsum & the cement in the addy.

As with all trades, you do need to be careful when selecting. You might be surprised to learn that many who call themselves “pro tilers” don’t really have much of a clue about tiling; always best to get recommendations & look at previous work, if he’s any good he won’t mind at all.