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)

 

[Hawk Tuah]

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)

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.

 

[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

 

[b0rn2sk8]

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.

 

[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.

 

[Guitarcarfanatic]

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.

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!

 

[Hawk Tuah]

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.

 

[b0rn2sk8]

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.

 

[Showboat]

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

 

[200sols]

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?

 

[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)

 

[Hawk Tuah]

Mine's almost the same, however I removed the angled compression section and solvent welded the flexi to the shower trap. The only compression left is the one the other side of the flexi to the waste pipe - in-case I need to ever remove it.

The seal between the waste and the shower tray is the one that I was most concerned with. I did what you're doing on my first shower, and had a small leak from that connection (fortunately spotted it before ever using the shower). Pretty sure mine was the McAlpine as well. It's quite difficult to tighten it sufficiently from above. That's why on the most recent one I connected the trap to the tray first when I had access to the top and bottom of the tray, then to the waste pipe while the tray was suspended a bit higher than it's final position. High enough so I could get my hand in and connect it, and a torch to check it was water tight.

 

[200sols]

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

 

[b0rn2sk8]

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

 

[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..

 

[b0rn2sk8]

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!).

 

[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...

 

[Hawk Tuah]

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.

 

[Participant]

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.

He can recess the bath into the breeze blocks to some degree if required.

 

[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.