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

[Buffman]

Hi all, I want to put a shower where the previous units where and a small bathtub adjacent.

Upon removing the wall I realise it's relatively smoothly plastered. I believe it's dot and dab onto plasterboard.

Is it possible to tile straight onto this wall without taking it all off / back to brick? Is it worthwhile applying waterproof tanking straight onto this back plastered wall?

Would I be better knocking the plastered wall back to brick. Then applying a tanking compound?

I will be having the pipework seperately installed by a plumber as part of a larger package of works (installing radiators/replacing all microbore pipework). The radiator will be moved from its current position to adjacent the door.

I will also be seperately getting a tiler in and walls that aren't tiled plastered by a plasterer.

Basically main "DIY" element is replacing flooring and sorting drainage for bath and shower and also fitting units.


Would appreciate any articles people can link!



Can see the flooring is a little knackered! I need to fit a shower above this...

 

[Buffman]

You can tile onto plaster or plasterboard, there are weight limits and it is relatively low for a plastered wall. You tank the wall substrate (plaster or plasterboard) then you tile.

Reinforce that floor area below the shower to ensure it doesn't move.

Regarding Tiling
Yeah I've read "20kg/m2" if the area is already skimmed similar to mine above. Do most tiling

Regarding tanking compound / securing wall
If its already skimmed is there value in me also drilling and fixing the existing boards to ensure they are as "secure" as possibe - these would be fillered before tanking

I'm thinking something like this might be suitable?
https://www.screwfix.com/p/mapei-shower-waterproofing-kit/78484

video below seems alright with all corners filled
https://www.youtube.com/watch?v=TLr1_esRyFw

regarding flooring:
yes I'm going to complete replace the subfloor - I'm thinking either waterproof plywood of green chipboard then hardie backer on top (is the later a cheap bodge?)

in the areas where the joists have been heavily notched I'm also tempted to tie something to them? Know the best type of wood to do this?

 

[Buffman]

Replace the plasterboard with a leak proof solution?

Don't just tank walls, moisture proof plasterboard, silicone the gaps etc... it will leak in time.

apologies didnt see your response earlier, if you see my following post I was thinking of using something like this:
https://www.youtube.com/watch?v=TLr1_esRyFw

It appears on the face of it like a much better solution than a previous bathroom install I had by a plumber ( plastered straight onto brick then tiled). In addition to the above I could also notch the shower tray into the walls? (depending on size of tray/if required).

Chipboard overplayed with hardibacker is pretty standard and works well if tiling the floor. To strengthen the joists just use some c16 timber.

Thanks. Are you in the trades out of interest? So do you think my approach with above video/tanking/taping will be fairly sound?

Do most tiling outfits identify the weight per square metre? just need to check 20kg/m2 is suitable..

 

[Buffman]

You can tile directly onto plasterboard, the tile companies etc say no, and yet its what all housebuilders do.
I am mid install of a new bathroom and getting the old tiles off the plasterboard was a nightmare. In some large areas I just nuked it back to the studs and have reboarded, the state of the old boards was just not worth the effort of trying to fix them up.
The only places that were easy to salvage were the ones where clearly the tiler didnt just skim a massive chunk of wall with adhesive and tile that patch, but had to tile round things, and as such was clearly doing it tile by tile (from the adhesive pattern)

As long as you stud wall is nice and solid and the what looks like plaster skim is solid, I wouldn't have any issues personally.

Tiles seem to come off plaster easier than plasterboard I find. I suspect the adhesive works into the paper covering of the board which means its practically impossible to get off with out at least some surface damage.

Mine is dot and dab onto a brick wall i.e. plasterboard on a brick wall. other than that yeah a couple sources I've read identify its OK. Only thing is I'm not sure how to ensure the fix to the wall is "nice and solid" - I suppose I could rawlplug and fix it to the wall every (say) 600mm just to make doubly sure?

https://www.toppstiles.co.uk/knowledge-base/tiling-onto-plasterboard

https://www.diydoctor.org.uk/projects/waterproofing-wetrooms-and-bathrooms.htm

 

[Buffman]

2 more questions if anyone feels like answering
Wall of tiles
Any ideas what the grey is on this wall? I wasn't sure if it was a blockwork type but it seems to be flush with the plaster?
I could knock it off but wasn't entirely sure if it's blockwork or not



Soil pipe connection

Ive realised the connection for the soil pipe is very high from the bath (existing Annotated red from below) , is there any issue with coring a new hole lower down? - other than it being quite ugly which I appreciate... The soil pipe is already a bit botched/hideous.

Problem with the current position is that I won't be able to fit both a shower and a seperate bath which I want (without raising the shower to a significant height which puts me off)

 

[Buffman]

I've now looked under the current bath and my god its a total mess of pipework, but also realise the pipes that feed the en suite on the back wall adjacent are at floor level rather than below the floor - this somewhat limits having a seperate shower and seperate bath

With that in mind I'm considering adopting something similar to the below (built in storage adjacent the existing shower) with a shower on the bath also (on the studwork wall with storage). Generally I dont like having a "shower bath" but guess I might as well to allow me to keep the en suite in the room next to it (without a major overhaul of that).



Only thing I also need to check with the existing en suite is wether its leaking (and where) as currently after taking the wallpaper off the ceiling it appears theres been a leak at some point - I just dont know when. Any easy way to check other than run the shower a for say 30 mins or an hour and see if the ceiling feels wet? Currently I dont use that shower as the thermostatic mixer is broken (which I can seperately easily replace/fix)


Alternatively I can take the plasterboard off from the ceiling beneath the en suite shower and possibly get my plumber to refeed the pipework from under the joists. a bit arse backwards but may be worthwhile..

 

[Buffman]

Is it usual to have this much pipework under bath but above floorboards?

Im tempted to "stud off" the yellow wall by 50mm or so, conceal the pipework tothe ensuite and this will allow me to fit a show on the "right" in below pic and also a small bath for if i have kids

Any thoughts?

 

[Buffman]

That's a bit chaotic, don't see any reason why any of those cant be under the floor.
Thinking out loud the ensuite plumbing is probably like that rather than taking the bath out at the time the ensuite was done.

Aye that will be why it's the way it is (numpties had this house before me ).

One other thing I was thinking was if the plumber could redo the pipework from underneath the ensuite (the room beneath im later going to get reskimmed anyways). Only issue there is they'd have to open up the plasterboard (or I could do this) then also the flooring under the ensuite. Not sure if that's actually possible or if it's going to be too cramped to joint the pipework from between the raised tray and any cut openings in the flooring. Also possibly not a great idea for the flooring? Means in future that en suite wouldn't need a raised tray though..

 

[Buffman]

You could fit a raised shower over those pipes anyway, have you checked below if it is possible to route a waste pipe for the shower if it was flush to the floor? Studding off a bit of wall has advantages anyway, like being able to fit a concealed shower valve if you wanted to.

Yeah I considering a raised shower tray but I don't really like them to be honest if they can be avoided.

What do you mean by concealed shower Valve?

Aye there would be room to fit the shower drain adjacent the joists/ under the floor. It would also mean it's further away from the existing which is possibly structurally "better".

 

[Buffman]

We had a water feature in the living room every time someone had a shower. Turns out previous owner hadn't bothered tanking the ensuite shower walls before tiling I fixed it by raking the old cracked grouting out and putting fresh grout in. But I'm going to have to keep a close eye on it now.

Ah what a pain!

why have you got lead pipes ?get rid of them .. by now the leads breaking down .. or at least get a water test .. once lead is in your body it's very hard to get out ..

They're not lead, it's a mixture of copper and plastic (and nothing tied down/clipped anywhere
) surprised I don't have more problems with water hammer!

They can be made to look good, the raised bit doesnt just need to be white, it can be tiled in to match the walls or floor.

Basically all the pipework is hidden in the walls, the only exposed bit is the lever and shower head.

https://www.bristan.com/concealed-showers
https://www.bristan.com/bar-showers

Ah cool yep I know what you mean! Aye those look nice but don't think I need them / will probably just go for standard thermostatic mixer (from a decent brand! - grohe or bristan probably)

 

[Buffman]

As above. Can’t go wrong with Marmox in my experience

sounds good, I might go for the long sheets e.g. the below
https://www.tilefixdirect.com/product/Marmox-Multiboard-Tile-Backer-Insulation-Boards#MX625-125
plus shower niches:
https://www.tilefixdirect.com/product/Marmox-Niches#MXNICHE-4040

Is there anywhere I can buy 100mm sets of timber to stud out one wall? Is C16 grade timber the most suitable for studding out inside a bathroom? Is 600 centred timbers sufficient? (I could just buy the 600 wide boardsx2500 height)


E.g. this for studding out wall

https://www.travisperkins.co.uk/cls...-100mm-finished-size-38mm-x-89mm/p/9000098434

 

[Buffman]

To give this thread a bit of an update, I've finally taken the plaster off, as I'm renovating the rest of the house (most recently having the back end structural wall taken out) this has been on the back burner.

I think I'll go for that jackoboard referenced earlier. Is 12.5mm OK for dot and dab? (should I go thinner?) I've read you need minimum 20mm boards for 600mm wide stud walls, but i have a very small section of stud wall 400mm wide. Will that be OK?

Can jackoboard also be used instead of hardie backer on the floor or is hardiebacker better?


The dot and dab adhesive was strong! Plumber is coming Tuesday and sorting out the pipework under the old bath and chasing pipework in for the shower.

 

[Buffman]

I would use 6mm hardibacker.

Cool how come you prefer hardie backer to marmox or jackoboards?

Does the hardie backer need to be glued and screwed to the chipboard floor? I think my last house my plumber just screwed it. (possibly a bodge!) only thing is I'll need to use short screws as my floor is full of pipes and cables.

 

[Buffman]

• Do people tend to run water proof boards down to floor then have the shower tray installed up to these with tiles on top?
• Do people tend to put backer boards underneath the shower tray e.g. Hardie backer?
• Is fixing the shower tray down with tile adhesive best bet? Could use the same adhesive I dot and dab boards with?
• Whats the best adhesive to dab the jackoboards to wall with?

Are there any good websites for tips on this?

Also - had my pipework sorted by my plumber yesterday so (almost) ready to put floor down. Bought some 18mm waterproof chipboard for the base.

Thinking of going for this tray (possibly in 1400 by 800 size)

https://www.screwfix.com/p/mira-flight-safe-rectangular-shower-tray-white-1400-x-760-x-40mm/5622x

 

[Buffman]

It depends, when I did my en-suite, the area where the shower tray went was only 121cm between the studs so a 120cm shower tray was slightly recessed into the wall boards (marmox) on both sides. It’s a very right room!

I made sure to use a waterproofing membrane between the back of the marmox board and the sides of the shower tray to ensure and leaks are contained in the tray. The gap between the tray and the marmox was then sealed before a final finish (shower panels) and final seal was put on top.

In total there are 3 layers of leak protection between the walls of the shower and the tray of the shower.

If the gap for the tray was wider the marmox boards would have been fitted to the floor on both sides and the seal between the tray and the shower would have been put on the front/inside rather than the back/outside (hope that makes sense!).

I didn’t put any marmox on the floor. There want any need to raise the floor level and it was already solid and smooth. It being solid and flat is very important though.

I stuck our shower tray (plastic) down with good amount silicone, it isn’t going anywhere and good luck to whoever needs to remove it. I’d follow the instructions from the manufacturer for the tray and the surface it’s being stuck to.

I would have thought the manufacturer for jackoboards would recommend a specific product, otherwise standard dot dab adhesive will do the job.

Edit: I’ve got that tray in 120 x 70(maybe 75!?). It’s very low profile which is exactly what we wanted.

As with any low profile tray just make sure your drainage is good and flows properly. If there is any backing up from a blockage, even a small partial one if you have a high flow shower, you’ll over flow the tray in seconds as it only holds a few of litres of water.

Ah cool, yup I have a just over 1400 gap (pics below). I think i might put waterproof boards over the already 2 layers of plasterboard to bring it tight to 1400 so the shower is well enclosed.

Ah cool, for the tray I paid extra to get the "antislip" version.

Im also thinking about putting shower niches in this side. It's only 70mm deep stud wall but plus the 2 layers total 25mm of plasterboard that's 95mm ish.

Its the main family bathroom upstairs but very tight!

Ive just bought this bath and also a 10mm screen (nearly £1k just on bath and shower + screen!)
https://www.drench.co.uk/p/armourca...rcast-bloque-1400mm-x-700mm-single-ended-bath

Thinking about shower recesses/niches in red here, back of stud wall in other pics below.

 

[Buffman]

I'm guessing it doesn't matter if i use these niches with jackoboard if they are my preferred size ? Or would I be better going scluter brand all round?


https://www.protilertools.co.uk/pro...d-sn-shower-niches-305mm-x-711mm-x-89mm/47229

 

[Buffman]

@200sols thanks! I'm going to order from protilertools most likely so the links are great for me.


I like your Grohe " built in" toilet - very neat! Need to look for a sink and toilet unit to accomodate around 1700 wide at mine.

No I won't do the tiling myself, the intention is to do all the waterproofing substrate, floor etc and then find a good tiler. Bad idea?


My main thing was the previous bathroom I had fitted the overall tile finish wasn't great and I wanted to make sure it had a good finish, also I've already had the plumbing and electric works done by others (and the ceiling will be plastered) as part of an overall house renovation that's ongoing.

 

[Buffman]

Another question, do you think I should tank all over the plastered walls? I was going to just tank the shower and bath walls initially

I realise i might need need to plastered around the radiator pipes adjacent toilet before they can be tiled (so there is a flat surface to tile to?)

- if I don't do the wall adjacent the bath I suppose that is a " weak point? Only concern is if I dot and dab 12.5mm boards that will be deeper than the unplastered portion for tiling thus will need to do the whole wall

 

[Buffman]

You only need to tank the wet areas and if using those tile boards you only need to tape them. Easy.

Are you sure you want a 1400mm long bath? Seems pointless.

Ah cool, the tile adhesive is totally shagged above the sink which I'm currently taking out so might got up to that. Could i fit 6mm boards to the brick wallso that they align to the plastered wall? (the plaster is straight onto brick)

Also! Just found a massive plasterboard hole above the mirror was an air brick pre extension

The 1400 bath is just for if we have kids or the dog. I don't like baths and wouldn't have one if just for me, just thinking ahead.

 

[Buffman]

Shower base should be on a mortar base. You don’t want adhesive as it can cause the base the delaminate due to it sticking to the base. If you use adhesive then put a plastic layer between the adhesive and the tray.

Is that really an issue if its a stone resin shower tray?