Tanking Niches

[David Dudley]

Hi.

New forum member here, just discovered the forum only a few weeks ago. Have seen some great threads of other projects on the go and also learnt alot in the process.

I have quite a large project on the go at the min renovating a 5 bed hosue (planned over a few years).
The house was built in the 70's and is completely original from when it was built.

I have recently re-boarded one of the en-suite bathrooms, using moisture resistant plasterboard and plastered the ceiling, and the upper quarter of the walls (for painting). We are installing an offset corner bath, with mira atom shower bar above, and shower screen. The plan is to tile around the bath area up to the painted level.
I really want to make sure that the whole area is protected from leaks so I intend to tank the plasterboard that is to be tiled with Mapei WPS.

My main question is regarding some niches I have installed into the stud wall. The stud was doubled up 3x2, so 6 inches deep and seemed to be a good use of the dead space. I built these using ply and then lined using MR plasterboard. I also built into a slight downslope on the ledge so that water will run out.

My understanding is that I can tank these using Mapei WPS and Mapeband to fill edges. I will then tile using mosaics.

Will this be effective in sealing the board and stopping water passing through and into the wall? Any other things that I need to consider?

Photo attached.



Thanks.
David.

 

[davemul]

Should be fine, I did exactly the same as you in my bathroom thread in my sig.. however I used waterproof marmox boards and not plasterboard.

Use waterproof tape on all the joints, corners... everywhere!

Then give a good few coats of mapegum!

You should be fine with that

 

[Time's Ran Out]

As per Davemul - I'd have gone the way of tile backer boards over MR plasterboard.

 

[Stewart]

I use Marmox backer board for mine...

Created on iPhone.....

 

[David Dudley]

Thanks for the comments guys. The niches were a last minute idea and I already had the plasterboard.

Is this a problem or will the tanking solution seal it?

 

[David Dudley]

Just had another thought. Would it be a good idea to silicone all the joints before I tape and coat with mapegum?
There are quite a few gaps (2-3mm wide) that need sealing where the boards meet.

I could replace the board with tile backer or marmox if really necessary but that would be a hassle I don't really need and the tile weight isn't going to be an issue so I'm not sure if I would gain anything.

If the mapegum is effective at waterproofing plasterboard then I guess the board doesn't actually matter for such a small niche?

My only concern is water proofing it all as the bathroom is directly over a living room.

My plan is to:
Silicone round the boards,
mapegum wps
tape all joins
then re-coat with mapegum
tile using bagged adhesive
then silicone all corners

Is this the best way to go?

 

[Gazebo]

Hi David

I use marmox boards also but the way you have suggested should be fine, any yes silicone the board joints 1st as an extra precaution.


Good luck
Gary
[email protected]

 

[davemul]

As already said, yep silicone too. I did this also. Silicone the screw heads and around where they penetrate the boards too

 

[David Dudley]

Thanks alot guys. Does the tanking solution stick to the silicone ok?
Should I be using acrylci silicone or normal silicone?

Thanks again.

 

[davemul]

I used Marmox acrylic just to be safe
An Acrylic Waterproof Sealant, ideal for use with Marmox products.

 

[PHG Dave]

Thanks alot guys. Does the tanking solution stick to the silicone ok?
Should I be using acrylci silicone or normal silicone?

Thanks again.

Nothing much sticks to silicone (Acyrlic and silicone are two different materials)

Personally do not see the point in silicone in the joints, if water gets through the membrane then it can go through the boards as they are only water resistant not waterproof.
Your original plan of Mapeband (or Dural's DURABASE Flex sealing tape) and Mapegum is perfect for the job

 

[David Dudley]

Thanks PHG.

Would the ditra matting be a better solution altogether? I understand this is applied with the same flexible adhesive used to stick the tiles?

Also (as posted in another thread) I have an 18mm marine ply floor. I laid this thinking it was the right thing to do. Unfortunately didn't seal it first.
I was thinking of using the ditra uncoupling membrane with this? Would that solve any issues with the ply? I am only waterproofing the floor to make it leak proof/splash proof as its a bath with shower above and not a dedicated wetroom?

Thanks again.