Wet-Room Tanking/full water proof

21 Jan 2017
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United Kingdom
Hi guys,

I am in the final process of completing my wetroom prep before tiling. All that is needed is the waterproofing and my mortar bed slope to the linear drain.

I have applied waterproof backer boards, now I am ready for tanking/waterproofing.

My question is should I fully Tank my backer boards wetroom or just the corners/edges and where the seams of each board meet?

I feel that the whole room is not necessary as the board itself is a cement front, foam backer waterproof. Only the corners (in/outs) edges and seams.

Your thoughts and opinions on this, please. Below is the room.


Thank you.

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My advice would be to tank the whole lot.
I used an Aquaseal Tanking Kit (other makes are available) on my ensuite shower.
The kit has tape for the joins and corners which you do first. Then 2 coats of the tanking solution. This is painted on and sets to a solid rubber type finish. You then tile on top.

I would board the blockwork as well, as that is quite porous...

@curry-kid Thanks ever so much mate. I have just ordered myself a kit for that. Will also go ahead and do the board block work also. Mate would it be possible if you could possibly check my other 2 forum thread relative to this wet room. There are just different types of questions though would be grateful if you could check them out and give me your opinion, please. I have put the links below.



Thanks mate.
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So yes, I would board the blockwork bench. Do the top and sides.
I wouldn't bother trying to recess the board under the wall boards.
If you tape the joint before tanking then it won't make any difference which is on top.

I can't help much with the mortar bed slope.
You definitely need a membrane under the tiles. Grout will always eventually let water through especially on the floor, so you need something underneath.
Looking at where your linear drain is, you have it very close to the block wall. Usually they are at least a few inches away from the end wall. You might struggle to get the board in and tile down to the floor.

I'm no expert, but whenever I have seen UK wetrooms being installed they use something like this to form the floor:

But if you are forming the slope yourself, then you will need a membrane between the mortar and the tiles. Something like this:

And you need to tape and tank the walls onto the floor membrane.


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