Should we bother with tanking in bathroom, advice please

28 Jun 2005
Reaction score
United Kingdom
Hi My friend is putting in a whole new bathroom and has insisted I help him as I used to do building services and was pretty handy. He got some moisture resistant plasterboard, the green stuff, and used that on one stud wall and then he had this really rough brick wall one end with bricks protruding for which he asked me to help him dot & dab the boards on to.

We chipped off the worst protrusions off and then brushed the wall down to get rid of any dust or loose material first. I told him to check if dot & dab was ok for bathrooms but someone had advised him that it was ok so we went with that idea.

He is having a bath with a wall shower, with pipes and mixer in the stud wall. What I would like to know is whether to tank the area around the bath, shower or both, bearing in mind he has used green board.

I did a bathroom a while back and with that it was just a shower and no bath and I tanked the shower area with what I think was called a Bal W1 kit, but should this be done also around the bath especially around the shower area?

If it were my own I think I would anyway just as belt and braces even if I had used green board but what is the correct way to do this job where tanking is concerned, around the shower area only or around the whole lot?

I should add the whole area around the bath is to be tiled.

Any advice or help appreciated.
Sponsored Links
Yep tank it. moisture resistant is only moisture resistant - think steam\condensation etc.

if any water gets into contact with it it will disintegrate. Bal WP1 is very good and easy to apply. we sell a palace kit and have good feedback about that. for the sake of 50-60 quid its not worth the risk.

dot and dab - lots do it and its usually fine if done well. failures usually come from skimping with the dabs and i have seen some horror shows - one dab every metre on one job that failed!
You don't mention what tile you are using but if they are big and heavy dot and dab can be an issue.
Yes tank the wet areas but TBH, you'd have done better to use a waterproof tile backer board & tiled straight onto that; personally I never use PB of any sort in a wet area. If you’re tiling D&D PB with tiles of any significant weight, you need additional mechanical fixings, especially if your laying those 900mm x 350mm tiles you posted on your other thread. As I posted there, check the tile weight; whilst un-plastered PB & WP1 will take 32 kg/sqm, the bond will only be as strong as whatever your fixing to; hence the need for mechanical fixings or the whole lot could end up on the floor.
Sponsored Links
Tank the lot with a membrane- Kerdi or homelux. Paint on Tanking is old hat and it slows the job down a lot.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local