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...

 

[200sols]

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.

 

[SquirrelMadness]

Replace the plasterboard with a leak proof solution?

See that stuff on the walls in the background... You want that stuck to the brick/block wall, all taped and sealed.

I have a friend who did what you're wanting to do (tank walls then tile) and she has leak problems now after 1 year.

I wouldn't ever install a bathroom without some type of system to leak proof it under the tiles, there are various companies that make them. Pick a brand and stick with it.

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

 

[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?

 

[200sols]

I have a friend who did what you're wanting to do (tank walls then tile) and she has leak problems now after 1 year.

She didn't do a very good job then tbh.

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?

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

 

[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..

 

[Mercenary Keyboard Warrior]

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.

 

[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

 

[200sols]

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..

Not a trade but I've done a lot of DIY work. FWIW in my bathrooms I ripped it all.back to studs/bare wall and boarded them with proper waterproof tile boards which have many advantages over plasterboard.but tanking systems like you linked are used in probably 95% of bathrooms out there.

For tile weights ceramic and small format porcelain you will be fine, large format porcelain and natural stone you will need to look at different substrates to plaster. Bare plasterboard is better than plaster BTW.

, the tile companies etc say no, and yet its what all housebuilders do.

Really? Never heard tile companies saying that!

 

[b0rn2sk8]

If the wall is smooth and flat then just tank it with a suitable membrane. Tanking is a secondary defence against moisture and isn’t there to be relied upon. Your primary finish should be doing all of the work keeping the water where it should be.

I replaced the boards with Marmox in my shower room because the plasterboard was wrecked but I would have just tanked it had they have been fine.

The old tiles in the bathroom on the other hand came off fine and I just tanked that one.

stripping out perfectly good boards is not the most effective use of money, particularly just for a shower cubicle. The alternatives to plasterboard are good but they also cost significantly more.

 

[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)

 

[Mercenary Keyboard Warrior]

Re the grey, looks like its just been patched with cement type mortar, probably to replace some previous tile removal damage.
I wouldnt worry unless its unsound. If its sound just tile over.

 

[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?

 

[JRJ]

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.

Personally I'd be getting them under the floors and fixing 2x1 batten to the yellow wall plus tile backer to give me a void to conceal the shower pipes, you could also mount a concealed bath tap on the same wall which would allow you a shorter bath but still be full size if that makes sense as the taps wont be mounted on it

 

[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..

 

[200sols]

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.

 

[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".

 

[IvanDobskey]

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.

 

[flea.rider]

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 ..