Shower Waste joints not accessible ?

[SproutsDad]

Your advice please.
I am making a downstairs shower room with a low profile quadrant tray, in what was previously a typical 1930's kitchen - the original concrete floor stepped down 120mm from the rest of the house.
But that floor has now been built up with joists and 22mm plywood to match the ground floor level.

The 40mm solvent welded shower waste runs in that void, joining the tray at the McAlpine ST90CPB-P-70 trap - but the last 2 joints are the trap's own compression connectors with their sealing washers - that part is my concern!
>> See photos

My Concern >> Once the tray is lowered, fastened and the trap sealed to the tray from above, that will be permanent with no way of ever knowing if any leaks should occur over time?

But this is non-pressure waste for an occasional used shower, and I am using the McAlpine trap which is a quality recommended item.
However, I'm still concerned for those hidden compression joints in particular.

> A couple of plumbers have told me to just seal it up with low-modulus or CT1 sealant on everything and it will be fine !.

> I do not want to build up a 3"/ 75mm raised platform for the shower tray to sit on. I know that could give access, but I feel it looks ugly and defeats the object of a low shower ingress.
And in that case I still wouldn't be aware of any leaking, raised or not. And unless it had an access panel on the side of the platform that could be opened for inspection periodically, I wouldn't know if it was leaking. I don't see much benefit going that route.

Q? > But am I worrying about this unnecessarily? Should I follow the advice to do a belt and braces sealant job and just close it up?

And if this pipework was all buried in concrete, which is quite usual, it would be solvent weld the whole way, so would we then worry about this?

Q?> Or should I do something about this and either:-
1> Somehow make the whole waste run including the trap in solvent weld? But that would perhaps mean using a different trap without these compression joints?
Or ...
2> Look at some kind of small floor access trap that can take the tiles and just leaves a neat couple of stainless bolts?

Your help and advice is welcomed.
Thanks very much

 

[Bonni]

Put water in it now to check for leaks, or am I missing something?

 

[Madrab]

+1, run a few kettles of water down the trap and then check everything for leaks. As long as there is no stress on any of the joints it shouldn't leak.

Don't use any sealant/adhesive on new clean fittings, it can actually create leaks if the seals squeeze and shift when being tightened, as the silicone acts as a lubricant until it dries.

 

[SproutsDad]

Put water in it now to check for leaks, or am I missing something?

Thanks for your reply, yes I was going to do a leak test, possibly try and block the waste further down to hold water in it overnight and then check again.
But more fundamentally, would you continue with this approach to close it all up with no future access? That was my concern.
Thanks

 

[SproutsDad]

+1, run a few kettles of water down the trap and then check everything for leaks. As long as there is no stress on any of the joints it shouldn't leak.

Don't use any sealant/adhesive on new clean fittings, it can actually create leaks if the seals squeeze and shift when being tightened, as the silicone acts as a lubricant until it dries.

Thanks Madrab - I heard similar warnings about using sealants on rubber seals, I get what you're saying. Problem for people like me is that there is so much "oh, it'll be alright mate" comment out there and these 'plumbers' had said to use sealant with rubber seals.

So again, would you be ok closing this up with compression joints inside and not go the route of having some form of access?
Normally it seems such waste installations are upstairs with a ceiling beneath for access in emergencies, or are a complete solvent welded waste run in concrete on a ground floor.

 

[Madrab]

If access can be arranged then that's ideal, personally I'd try to manufacture access into the design.

If it can't though then all you can do is test and trust in that once it's shown to be dry. Just remember not to have any joint under stress, as long as you do that then there's nothing else anyone can do to ensure a dry run.

 

[SproutsDad]

If access can be arranged then that's ideal, personally I'd try to manufacture access into the design.

Thanks, I agree. Any access will have to be a small floor trap that seals watertight and takes the floor tiling - in this case the floor covering is vinyl Karndean.

It would need to be next to the tray, allowing a hand to get in to the joints on the the trap. I have in mind about 150 to 200mm square?

You see such access panels in commercial buildings.
Does that sound ok and if so any ideas what exactly and where to get it from?

I feel that I could later regret not going this access panel route. The floor void could take a lot of water before showing signs of any leak years later.

 

[Sonic70]

I would put some form of access in, at least you can check the fitting every so often.

 

[lostinthelight]

Unless the trap is solvent weldable theres going to be a removable joint where it joins the SW.
Where I have a compression fitting under the floor , before I fixed the PB and skimmed I framed the joists under it so can take a square out if needed and new piece is easily screwed in .

 

[SproutsDad]

I would put some form of access in, at least you can check the fitting every so often.

Thanks. That's exactly my point. An upstairs bathroom leaky waste will at least show as a mark on the ceiling below, and is easy to open up, replace and redecorate.
But in this case, without some inspection access, it could be catastrophic under this void before anything showed, or smelled!

But is has to be a water sealed and easily opened floor trap. Any ideas anyone please?

 

[SproutsDad]

Unless the trap is solvent weldable theres going to be a removable joint where it joins the SW..

>> Maybe that has to be the best solution?
To somehow solvent weld or replace the 45deg compression elbow, or to swap for a trap that has solvent weld joints.
That could remove the doubt about what was going on under this floor., and the need for an access trap ??

Where I have a compression fitting under the floor , before I fixed the PB and skimmed I framed the joists under it so can take a square out if needed and new piece is easily screwed in .

Sorry is PB plasterboard? That sounds like you mean to gain access from the ceiling beneath?

My floor is in 22mm ply with concrete 120mm under it, not a ceiling, this is ground floor. Any access built in will have to be from the floor, meaning it has to seal watertight and lift upwards.

This type of thing works, seals, but sits proud of the floor and doesn't blend in, but the principle is right. A small square and flush alternative would work
https://www.jupiterblue.co.uk/access-panels-and-access-hatches-c1/waterproof-c16

Any ideas anyone please?

 

[oldbutnotdead]

Tricky one- with those 2 x 45 bends and the woodwork, an external trapdoor isn't going to work.
To put your mind at rest (hopefully) I had a similar puzzle about 6 years ago- shower in what was the coalhole. My solution was to position the waste nearest to the outside wall, shutter a hole in the concrete to accommodate the trap, smacked a hole in the outside wall big enough to get the trap out and in if needed. Fitted tray, waste etc., stuffed void with rockwool, covered the hole with a sheet of marine ply (it emerges under the floor in the outside loo so not aesthetically shoddy, if it had emerged into daylight I'd have cored a hole in a brick and pointed it into the gap.
6 years later, regularly used, zero leaks. All compression or pushfit fittings as well (accessible so why not).
With your setup, all i can think of is to tank the pipe route and trap area (line it with dpm or similar) to where you can see it, if you do get a leak at least you'll know about it. As others have said, make sure the compression joints are square and not twisted, use some red rubber grease on them if you want, relax & enjoy

 

[dilalio]

Have some faith.
I regularly have to install inaccessible wastes to shower trays. Sometimes your hand is forced.

 

[SproutsDad]

Tricky one- with those 2 x 45 bends and the woodwork, an external trapdoor isn't going to work......... .

Thanks, and I agree, I have had similar situations with lots of 'just in case' work, and like you say "six years later, no leaks . .", even 20 years later. But Sod's or Murphy's Law . . . . .!!

As much as I want to do this 'properly', there is a lot of work involved finding and sourcing the right access panel - such things are sometimes difficult for the DIYer to get, commercial only - plus all the floor mods to accommodate it. And, unless it was a large opening and probably also an eyesore, all I would be able to do is see what was leaking and not easily fix / replace it, unless the whole trap could be pulled back through it!

With your setup, all I can think of is to tank the pipe route and trap area (line it with dpm or similar) to where you can see it, if you do get a leak at least you'll know about it.

I wish it was a contained area that could be tanked, but it is a 2m x 2m raised area of joists, Celotex and interlocking flooring plywood. Any leak couldn't be contained and would spread under the whole area, even further. The section under the shower tray is the only currently accessible part, the rest is finished glued down final flooring. And I wouldn't know about the leak without some form of access to inspect it periodically.

>> Proposal - How about this? Back to where I started. We wouldn't be having this conversation if as I said earlier, this was a complete solvent weld waste run! I would close it up no worries.
Q1 ? > ls there an alternative waste trap (or this one) that could be used with similar but solvent weld bends? No compression joints?
Q2 ? > Or, can the compression joints be sealed up on the outside of them somehow as a belt and braces? Would you perhaps wipe sealant around the outside of the whole tightened up joint ?

>> Either of these would I think bring closure - literally - and I could close it all up and forget about it. Your view on this please?

Thanks

 

[lostinthelight]

How about a moisture sensor under the floor if its not too late to fit, could give you of advanced warning of time to move