Re-tiling shower area in new home

[Spapro]

Morning guys,

I am after some advice if you could spare the time.

Moved into our new home 8 weeks ago and started using the shower cubicle fitted in the corner of the en-suite bathroom (which was largely unused by previous owners). After 6 weeks of use some of the tiles (just under the shower) started to bulge and ease themselves off the walls ! Tried getting in touch with previous owners who are not returning calls so decided just need to crack on and make the shower area good and usable.

I removed a few tiles which more or less fell off and have since removed the shower cubicle above the solid shower tray and knocked off all tiles from the entire 2 walled corner area which is enclosed by the shower cubicle. I am now able to see the 9.5mm ply-wood boarding which is clearly damp/mouldy in places and needs replacing.

I have also managed to source identical tiles from Homebase. I have purchased the BAL WP1 Waterproofing Kit, a bag of BAL Rapidset Flexible White adhesive and some BAL White Micromax Grout. So I am at the preparing the area stage.

I need to remove the 9.5mm ply-wood which is damp and mouldy. My questions are then around what boards to use and preparing the base for the tiling:

1. this is a stud wall - can I use 9.5mm plasterboard in place of the current 9.5mm rotten plywood? my tiles are 10mm thick porcelain tiles, and I am tiling from floor to ceiling. I will be using the primer/sealer from the Bal waterproofing kit. If I go up to 12.5mm plasterboard then I will have step where my repaired/re-tiled area meets up along one of the walls to the original tiling outside the shower cubicle. Sticking with 9.5mm plasterboard would avoid any step where the new tiling meets the old.

2. Happy to put in some extra wood into the stud wall frame to support 9.5mm plasterboard so if 9.5mm plasterboard will be ok with plenty of framing behind - what sort of framing spacing do I aim for - eg, a baton every 30mm, 45mm, 60mm behind the 9.5mm plasterboard ?

3. If 9.5mm plasterboard will be totally unsuitable and I do need to got to 12.5mm plasterboard what sort of spacing in the frame behind should I be aiming for ?

4. What type/length of screws would you recommend for fixing the plasterboard ahead of the waterproofing/tiling.

5. Do I need to do anything after primiing/waterproofing ahead of tiling or does the tile adhesive just go straight down onto the waterproof layer applied the plasterboard.

Thanks for any advice guys, I am trying to do the job right to avoid any future problems.

 

[AliGage]

9.5mm plasterboard is not suitable. 10mm porcelain suggests to me that these are potentially large format, they're certainly going to weigh a bit.
I would use 10mm marmox instead. You should be able to marry up to the other tiles with it and it can also hold 62Kg psm.

 

[White Room]

What you'll have to do first is when the ply comes off check the studwork is not damp due the excess of moisture because that moisture will soak into the plasterboard and render it useless.

 

[Spapro]

9.5mm plasterboard is not suitable. 10mm porcelain suggests to me that these are potentially large format, they're certainly going to weigh a bit.
I would use 10mm marmox instead. You should be able to marry up to the other tiles with it and it can also hold 62Kg psm.

Thanks Ali, I will take a look at Marmox board - they are large format tiles, 300mm x 600mm x 10mm thick.

Can I still use the Ball Waterproofing kit on the Marmox board in the same way - eg. coat of primer and then 2 coats of sealer ?

 

[AliGage]

Marmox is waterproof. You'll just need to tape and seal any joints.

 

[Spapro]

Marmox is waterproof. You'll just need to tape and seal any joints.

Thanks so much Ali, have taken a look and got that impression, so I just use the tape from the Bal Waterproofing kit on the joints - prime and seal the taped areas accordingly ? Do I need to prime the areas to be taped or the fact that the Marmox board is waterproof means no primer required ? just use the Bal tape and sealer straight onto the marmox board ?

Realised I used Marmox boards for installation between some undertile heating mat and a concrete slab floor in a conservatory at our last house. Hadn't considered marmox it for stud wall/wall tiling.

Looks like there are special Marmox washers available for fixing the boards - I guess its stainless steel screws with these marmox washers for fixing to the batons ? What length screws would you recommend ?

 

[AliGage]

I get my Marmox from tilefixdirect. They'll sell everything you need as far as joining tape, washers etc. If you can id take the WP1 kit back and save yourself some pennies.

Screws will more so be determined by the thickness of stud. I always opt for a screw that will make it 3/4's in. So for 3" timber id opt for 2.75" screw to also allow for the 10mm board.

Other suppliers are available. Check out some of the forum sponsors.

 

[AliGage]

P.s you don't need to prime Marmox

 

[White Room]

The screws for going into timber should be a course thread....

 

[Spapro]

The screws for going into timber should be a course thread....

Thanks Whitebeam, a quick search for course thread screws seems to just turn up drywall screws - are drywall screws ok ? read somewhere that drywall screws are not designed to be load bearing as such ?

 

[Qwerty]

Try a screw such as turbo gold ........a lot of retailers sell them

 

[AliGage]

As above, screwfix sell them. Brilliant screw, lol, as far as screws go!

 

[Time's Ran Out]

To me this is what this forum is all about - good questions, good advice and an OP wanting to do the job properly.
Welv done everyone .

 

[Spapro]

Hello guys, thanks for all your advice so far.

Put in the extra studwork and have attached most of the marmox boards to the area. My thoughts are now turning to tiling and wondering what you guys think of using something like a sealux strip along the edge of the shower tray prior to tiling - or am I just better with a neat, generous layer of smoothed Silicon.

I am quite neat with the Silicon but wondering if the sealux strips will give a more professional finish - stuck in place prior to applying the 10mm thick tiles.

Would appreciate your thoughts...

 

[Spapro]

Also, would you guys use a continuous bed of adhesive behind the tiles for a shower area ? I am using BAL adhesive - powdered, mix with water.

I have always used a serrated trowell for applying cement to the rear of the tiles - but have read should use a continuous bed of adhesive for shower areas but think that could be messy to apply in practice. Want to get this right though !