Advice for DIY install of bathroom and waterproofing walls - can I tile a dot and dabbed wall?

[Buffman]

Damn that's a lot of pipes and wires . Good work.

What's your floor build up going to be? I assume you're not going to tile directly onto that chipboard.

Underfloor heating going in?

Sorry if I've missed all that in the rest of the thread.

18mm chipboard (p5/waterproof grade)
6mm decoupling membrane
Tiles on top

No not bothered on underfloor heating... The heating circuit runs under the floor so I suppose it's heated that way (also have a big towel rad near the toilet due to very tight spacing)


Fitted more floor today and change some old electrical junction boxes to newer style wago boxes "maintenance free" although I realise they are only rated to 24amp for the 2.5mm squared cable so either need to find alternatives or de rate the MCB (only for upstairs sockets so fairly minor)

Im trying to work out now how to fit a shower drain at the other side with no access from the underside, wondering wether to use a Flexible drain coupling also (to allow some minor deviation in height)

 

[Buffman]

That's what I used for the final connection between the shower trap and the drainage piping (which was all solvent weld). I had the shower base up a few inches above where it would finally rest on a few polystyrene blocks, and tested it was water tight with a few jugs of water before removing the blocks and laying the base where it would end up.

Aye only reason Im considering it is I'll have no access from below. Some concerns a Flexi pipe will fill up full of crap/have poor flow? Not sure if my concern is unwarranted

Only reason Im concerned about solvent welding it is the process would go like below:
-Solvent welded waste fitting
-fix chipboard flooring down (suspended floor)
-fix shower tray down

Then I need to hope/pray the shower waste is in exactly the correct position as there will be very little manoeuvrability within the solvent welded pipework?

For what it's worth im also tanking the walls and want to fit the shower tray after I've boarded/ tanked the walls

 

[Buffman]

Any reason you can’t cut an access hole in the ceiling below and patch it up once done? That’s what I did with mine.

Aye i could do that, just don't think the patch would ever look perfect (and I'm fairly competent with fillering etc.).

I think i might go for the flexi waste and if there's problems in future could just access from below and amend it.

 

[Buffman]

I have just done exactly this - I am replacing a shower tray whilst trying to minimise disruption (it was all done recently floor to ceiling tiling, but the numpty who fitted the tray did an awful job!). I cut out the tiles around the tray, remove it and had to use a flexi to retain fall (limited access). Made fitting easy as took some stress for location out. If it causes me bother, I will access from below and redo the whole run of the waste to make it more direct in solvent weld.

Can recommend the McAlpine waste. My Mira flight tray came with a pretty decent vortex waste, but the McAlpine is leagues ahead!

Ah cool, yep I got the same tray and it does feel nice! Yeah I thought the waste that comes with the tray felt a bit cheap /poor so I also stumped up £30 ish for mcalpine one

I've had the same flexi on the shower tray I installed the same way this time last year. No issues with flow with either that or the recent one. Only time it slows down is when the trap is clogged with hair.

In an emergency, I could cut into it from below. But I'd really rather not.

I'm fact, my wife decided to do the ultimate test this weekend, without a heads up. She had a bath, then got out of the bath into the shower - whilst letting the bath drain. Both go into the same waste pipe. Fortunately, it all drained fine and no issues with flow with both draining at the same time.

Ah sounds good! Glad to hear some positive news from them. I've got my wastes from each seperate (due to the height of the existing bath drain)

I should have said, mine is also on flexi as the old pipes and new waste location were well out. I had to cut in a small access hole from below anyway to cut the existing pipe back to get the flexi in.

Huzzah, for once ocuk not telling me I'm a bodger

Cover up all those exposed openings on pipework, if a bit of dirt or stone gets in there it could slow things down draining or filling and will be a headscratcher trying to figure out where it is

Aye fair point on the feed lines! The drains are covered.

Use a good brand like mcalpine, don't use it at full extension and support the flex so it can't sag. With no access under the floor how do you plan to test it for leaks?

Yep I bought a mcalpine waste and all mcalpine fittings. To be fair i used a compression fitting on the end of the waste line as thats all I could buy today. The flexi section isn't significant. Got some pics below.

I tested it by pouring some water into it from a kettle and seemed fast flowing (got a good fall off the tray). I guess the only element that won't be able to test is the connection to the shower itself but the mcalpine waste seems fairly robust. I was also going to use sealant when fixing it down. Is Dow corning suitable? I won't be able to apply sealant to the underside but I guess it's just belt and braces.


Last section of flooring down today (not yet glued/screwed).

Ive decided I'm going to straighten up that corner stud section so the tiling job will be neater (going to get someone in for it)

 

[Buffman]

You can get traps which secure using screws, so much better.

The default Mira trap uses screws to clamp it in place which is what I used.

I was inclined to think the free trap provided with 2 screws won't be as good as using the threaded all the way round mcalpine trap, here's hoping! (I've got to tank all the walls etc before putting the tray in so it might be a couple of weeks..

 

[Buffman]

No issues or leaks with the Mira trap, you don’t need to clamp the screws down that hard either (not that you want to either as it’s plastic!).

Ah I just didn't use it as I thought the lack of waste catch also in it might cause issues (saying that Ive never lost a wedding ring etc in shower..) I heard mixed things about screwed ones also but you're probably correct and is fine for the application.

Now thinking about it I haven't even checked if the mcalpine trap fits . Should probably check that before laying it...

 

[Buffman]

Have you test fitted the bath + shower tray. That looks mighty close in the diagram, to the point where the thickness of adding tiles might make it too tight.

The diagram is not to that exact level of scale/detail (it's an extract of a drawing I marked up to annotate to my plumbers what I require)

The overall dimension is 2300, this gives 100mm "play" with a 800 tray and 1400 bath (2200). The dot and dab 10mm panels will take out approx 40mm out of this. I haven't tried dry fitting it yet although have it delivered.

 

[Buffman]

Shower trays and baths are fitted before tiling.

Aye i was going to fit my waterproof boards before both though as I think you and I previously discussed.

 

[Buffman]

Hopefully putting some boards on tomorrow. Put the niche in today (not aligned it as it will be "infront" of plasterboard.

Not entirely sure what the correct way is to fit the adjustable shelf on the schluter kerdi board shower niche either.

Realise I bought 10mm boards for walls but it claims "minimum" 12.5mm dot and dab. I'll just make sure its well secured.


Also I sharpened off the previous internal corner, as I hope this will make the tiling easier and neater. I also stuffed it with noise insulation as a bit of a belt and braces job.

 

[Buffman]

Are you putting that wiring into a conduit?

No, I don't believe it's necessary for the regulatory requirements. I also will know not to drill there. It'll be filled with sound insulation


Currently got the last piece of floor down, primed the walls and cut a couple boards.. Need to dot and dab them now..

 

[Buffman]

What do you mean the niche will be in front of the plasterboard? First photo looks flush. I'd have thought the thickness would be if you were relying on the plasterboard for support. Being attached to the frame would make that irrelevant.

Are you putting that wiring into a conduit?

I meant that the niche would need to be proud of the plasterboard so that the tiled surface was all level once he'd boarded it with a waterproof wall. But I really don't know if that's how it's done with these pre-fab niches, vs. keeping the niche flush with the plasterboard then putting marmox / other over the niche so that the tiled surface is flat.

Re: niche, there is currently was 2 x layers of 12.5mm plasterboard. I multi tooled one of them out and then put 10mm marmox behind it as a "packer". The schluter board is 12.5mm and marmox board I bought is 10mm. I thought there was only 6 and 10mm available but I was looking at the "tile backer boards" rather than the multi board on the site
. It sys 12.5mm is the minimum to dot and dab but I'm just doing it with the 10mm regardless.

I wasn't entirely sure which side was meant to be the tiled side but hope I've got it correct... (easier to key into the ridged side as photod)


Where the shower is going I have a 1400mm gap at its smallest and the tray is 1400mm
... That will be interesting.






Not sure if below gap between orange and blue too big or if i can just fill with tile adhesive plus the waterproofing strip above?

 

[Buffman]

Last night's efforts...need to get more timber in behind it for fixing to walls

I see that marmox says to use the multi bond between boards but I'm not sure if tile adhesive would be any better / more "waterproof" in the areas e.g. The shower I will be putting (expensive!) waterproof tape over all the joints anyways

 

[Buffman]

Tile adhesive is not waterproof. I already said silicone or multibond between boards and then waterproof tape. (Mesh tape is only for non wet areas)

Why did you put the niche so close to the wall as well, a tiny slither of tile up there is going to look bad.

Aye ill go over them with multi bond and waterproof tape.

The niche is in my preferred position, I considered centering it with the tray but would rather have it tucked in. I saw a couple examples on pinterest against the wall and looked OK after someone else pointed it out.

 

[Buffman]

The niche is in a nice position I think the comment is about whether you've allowed yourself any at all for the tile. You could end up with a tiny slither of tile versus an inch or two (i.e. not much more, but enough to make it not stand out).

Its got about 50mm, to the wall, so should be OK. You would literally only see it from the shower so not in a prominent area. Overall I'm OK with it after seeing some examples. The tray is 1400 / full width and the shower screen 900 so I didn't want to centre it and potentially get more water into the bathroom floor.

Im getting a tiler in so I'll see what they say re: niche.
I was going to try get nicer porcelain tiles rather than ceramic tiles I've previously had done.





Examples


Overall I appreciate the tiling on this pretty horrible

 

[Buffman]

Which of these best for dot and dab or completely combing adhesive into boards to fix to walls? I'm goinv to run out of the 2 bags of adhesive

Could I use ready mixed? Saves the dust and my lungs?

I'll be mechanically fixing to walls also
https://www.screwfix.com/p/mapei-rapid-set-wall-floor-adhesive-grey-20kg/29634

https://www.screwfix.com/p/mapei-ke...id-set-flexible-tile-adhesive-grey-20kg/7390v


The fact this is only linked to lightweight tiles puts me off
https://www.screwfix.com/p/mapei-buildfix-wall-tile-adhesive-off-white-15kg/5832c

 

[Buffman]

This one.

Used it lots, it starts to set fast the pot time after mixing is only 20-30minutes so keep that in mind.

Ready mix is for small tiles only, certainly not for dabbing backer boards!

Cheers! Ordered.

Put on a couple spankers today as a test and the rest of the timber section ties, definetly not a job for 8.30pm

 

[Buffman]

What's the preferred method to fix down shower bases?

My supplier (mira Flight tray) suggests sand/cement OR silicone sealant

For the sand /cement could i just use ready mix?

I also heard someone suggesting tile adhesive but believe it's frowned upon...


Also, presumably I would not need to prime chipboard floor before bedding in a shower tray with sand/cement? Fortunately the floor is fairly level.

 

[Buffman]

I have that tray, I used silicone and it isn’t going anywhere put it that way.

It does seem odd to be fair to put mortar down, I'm not entirely sure of the purpose if it's a stone tray? It's not going to move anywhere and effectively going to be "locked" in all sides. I have exactly 1400mm opening between panels for a 1400 tray

 

[Buffman]

To take up any unevenness in the floor. Don't overtaking this, if you use mortar absolutely prime the floor otherwise it won't stick.

When you say overtaking what do you mean? Presume typo OK!

Whats the group thoughts on ready mix mortar or using tile adhesive?

I recall reading a blend with more cement in is prefer IIRC

 

[Buffman]

most plumbers i know will use powdered tile adhesive now, go back 10 years and it was silicone but i think they realized silicone doesn't work when the floors aren't level/flat.

went to tile a job last year and the tray moved when i stood on it, it lifted up really easily and found it had been packed up to level with ready mixed to about 12mm on one side, after 2 weeks it was still so soft it had just sunk when i stood on it. the young plumber got a bollocking from his boss so hopefully wont do that again.

Ready mixed mortar or tile adhesive?

Also tonight's progress. Combing on the adhesive was a bit messy. Shoild have taken up a dust sheet! (got other rooms downstairs being plastered.


Need to buy more tile adhesive locally tomorrow. Wondering if C1F is OK instead of C2f. E.g using this for the wall by the sink

https://www.toolstation.com/mapei-fast-set-wall-floor-tile-adhesive/p99206