Waterproof Shower

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Ilovesun

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• Nov 8, 2015

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hi

my first post so please be gentle Anyone know best way to stop tray without up stands leaking?

I am a diyer just about to redo shower room that I put in 15 years ago. I used plasterboard and a tray with up stands and built in valve. Tray never leaked but tiles and or valve has, making lots of mould at back of plasterboard!I intend to use marmox on stud walls this time cos cheaper than wedi.
Shower tray size I want is not available with up stands so I was wondering if you could advise best way to ensure shower tray will not leak?

If I bed board on shower tray in Silicon and then use waterproof tape over joint, as belts and braces would that work? Only concern I had was that I believe the waterproof part of marmox is the extruded plastic middle and not the cement outer skin. The waterproof tape will be on outer skin so if water did penetrate would it roll down marmox middle and right behind the tape?

Picture attached to try and help explain my question.

 

tommyzooom

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Arms

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• Nov 8, 2015

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• #2 of 13

I would use a tanking kit, tank the walls, and use the sealing tape included as you descibed...
Or you could buy a flexible upstand, there are several makes... here's one...
http://aquastrap.com/

 

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Old Mod

• Nov 8, 2015

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• #3 of 13

As with any waterproof backer board, every time u puncture it with a dowel u break its waterproof integrity!
So u must seal and tape joints with manufacturers recommended system and seal over any mechanical fixings.
With use of tape around tray, if u place tape over tray and then tile down on top of it and cut back to tile when finished, this'll give u best chance of success.
These are tried and tested methods.
If u follow the basic rules u'll be fine!

 

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padtheplumber

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redditch

• Nov 9, 2015

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• #4 of 13

I would also make sure the tray is cemented down, it doesn't matter how well you fit / seal walls if there is movement in the tray its all for nothing.
The most common cause of leaks I come across in shower cubicles is tray movement.

 

AliGage

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• Nov 9, 2015

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• #5 of 13

Hi and welcome to the forum.

Personally I think trays with upstands encourage leaks. The bottom 20mm of tile to the tray is rarely stuck to anything. Even if tile adhesive is used here. It won't bond to the upstand well enough with any longevity.

What sort of tray have you purchased? Stone resin, plastic, lightweight/Foam based....?

Is it low profile or standard 4"? On legs or floor mounted? What is the floor constructed of?

 

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Ilovesun

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• Nov 9, 2015

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• #6 of 13

Thanks for the advice.
I haven't bought tray yet but was considering Mira flight or jt fusion both low profile About 40mm Stone resin capped with acrylic.. Current tray is on wbp ply platform on 4x2 on top of chipboard.
I am ripping that out screwing down chipboard and overlaying entire floor with 18mm marine ply. Then I was going to sand and cement tray onto ply. Redo walls to make sure all plumb and level cos I have bought the tiles 600x300x9mm porcelain.

I realise I have to use correct adhesive I was going to use mapei kerafix? Or similar.
Not sure what size trowel to use but I was going to use long marmox boards or maybe orbrey with the proper washers? Things have changed since I did the original one!! The cost of boards and self adhesive waterproof tape is a bit of a shock to the system

 

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Ilovesun

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• Nov 9, 2015

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Sorry I forgot one more question. What is best way to cut and drill porcelain (9mm)? I will be putting a bar valve in, so 2 largish holes and also a few straight cuts. I have a diy electric cutter which has been good doing smaller ceramic and travertine tiles but I think porcelain may be a different ball game?

 

AliGage

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• Nov 9, 2015

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• #8 of 13

Have I read this right? Your replacing chipboard and then over boarding with 18mm ply?

 

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Ilovesun

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• Nov 10, 2015

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AliGage said:

Have I read this right? Your replacing chipboard and then over boarding with 18mm ply?

Click to expand...

No I was going to put ply on existing chipboard after screwing it down.

 

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SJPurdy

• Nov 10, 2015

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• #10 of 13

Personally i'd just seal the Marmox to the tray with a flexible sealant/adhesive as shown in your drawing (as 2-3 mm Silicon rubber). I have never been able to understand how a tape cut down to less than the thickness of a tile can be expected to remain fixed to the tray if there is any movement - most (all?) those I have used can be peeled of the substrate with little effort (harder to get off fingers though), whereas an appropriate adhesive sealant will stick well to both tray and marmox edge allowing for some movement being taken up by stretching of the sealant. It would be an adhesive sealant rather than just Silicon rubber sealant as the adhesion of some makes of this (to trays) is also suspect. I would however use a good quality Silicon rubber sealant to seal the tiles to the tray.

 

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Ilovesun

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• Nov 10, 2015

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• #11 of 13

Thx once again, there is obviously more than one way to approach this waterproofing! I wish I had just installed it like the last one , plain old plasterboard no tanking and tubbed adhesive albeit with upstands And smallish ceramic tiles
But now I've read about it I feel I should do it properly!

What is difference between adhesive sealant and Silicon rubber sealant? Is dow Corning the Silicon rubber one, can you let me know an example of the other type?

 

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SJPurdy

• Nov 10, 2015

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• #12 of 13

If you were using Wedi board then they have there own sealant to joint all the boards which is very strong and negates the need to tape over joints.
I do not know if Marmox have something similar.
I have used "the works" to pre seal shower trays to tanked or backer boarded walls, and found it to be good.
For the Silicon rubber Mapei do a good range of colours to coordinate with their coloured grouts and I have found these bond very well. For white or clear I recommend the Dow Corning 785. Beware of cheaper Silicon rubber sealants as although some may be ok, I have come across some poor ones (don't stick, or don't set very well).
When I have tested various Silicon sealants and other sealant adhesives onto a glazed tile and let them set I found the adhesive sealants (I can't remember all the brands I used but the works was one) bonded to the tile beter than the Silicon rubber sealants hence why I have choosen to use these for pre-sealing.
Do make sure that the floor is rigid under the tray and that the tray is solidly bedded onto it, and that the marmox wall boards are correctly fitted (stud spacings, noggins, etc etc); otherwise any method of sealing that joint is going to be tested/exceeded.

 

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Ilovesun

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• Nov 10, 2015

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• #13 of 13

Many thanks, I will take a look at the works, in past I have used dow Corning for everything.