Shower leak - bit of a mare

[dormermike]

Had a shower leak. The usual thing with silicone needed redoing and the grouting wasn't the best. Redid all the silicone and regrouted the poor sections. Then discovered the trap hadn't been fitted properly, so redid that but had to replace the seals and top section but couldn't replace the lower part of the trap because it's been boxed in with 2x4 and only have 70mm clearance.

Problem is, it was absolutely soaking under there. I dried it out, and the chipboard base of the shower tray is black it was so soaked. Used shower against the wall and silicone etc after it all dried and all good. Continued to let underside dry out and used shower a couple of times. Check underneath after every shower... all good!

Except, went to have a shower earlier and checked underneath and it's soaking on the 2x4 frame farthest from the trap or any of the supply pipes.

I can't work out where it's coming from. There has been a mould patch on the ceiling which happens to be above the wet 2x4, but that would require water running down behind the tiles... could it? But... there is no sign of wetness above and no wet patch per se just condensation type black mold.

Exasperated! Considering a UV dye next....

Thanks for listening!

Mike

 

[dormermike]

Tldr - sealed most of the leaks but one remains, timing seems to take a while after last shower, and it goes from dry and soaking so hard to pin point where it's coming from. Almost looks like it's been misted or sprayed. Or condensation. Wierd.

 

[Madrab]

Sounds like it's a slow leak and it takes it s time to get to the point where it can get through.

Is it a plasterboard ceiling? May find it easier to open up the ceiling to find out where the problem is as it's only a bit of plasterboard and plaster to repair rather than pulling the tray out.

 

[dormermike]

Thanks. Yeah plasterboard ceiling above the shower but that's got 100mm celotex board above it, air gap, another plasterboard ceiling, then 100mm insulation and an air gap and finally chipboard for the attic. There are pipes below the chipboard but as far as I can see it's bone dry.

I've had a big fan running for four hours and most of it is being back to dry, except for the rearmost 2x4 which still looks wet. Access is a big problem. I've switched off the supply pipes to the shower which are piped thru from an adjacent utility room.

It was actually the bottom of the utility room wall being wet which alerted me to the leak initially. It's still wet.

It's possible I'm seeing condensation.

We had this bathroom refurbed in 2017 and I think it's been leaking since then as the trap etc not fitted properly, but the leak as worsened in last few months.

My plan now is leave it dry and see if it gets wet again without using the shower. If it does, it's likely a central heating pipe leak I think, as they run above just under the chipboard. It's possible the leak is running down and onto the celotex then draining off down the side behind the tiles and into the shower sub base.

If it stays dry it's possibly the shower feed pipes leaking inside that shower cubical so I'll turn on the cold then leave it and if still dry, then the hot.

I believe grout is not waterproof - could it be soaking through the grout then down behind the tiles? What is a good sealant for cement based grout?

Thanks if you got this far!

 

[Madrab]

Sorry @dormermike I was talking about opening up the ceiling below the shower tray to see under it or is the shower in the attic?

Most grout, once set is quite water resistant and is fine to be used in showers as they are not constantly wet or under water like in a pool but you can get a sealer that will make it more resistant and stop it staining. If the grout is cracked or missing then it can let in water and if the adhesive isn't properly applied and there's gaps then water can work it's way down and soak the floor.

 

[Wayners]

Water can run behind tiles along adhesive lines. Fixed some where water got through around shower mixer tap and runs behind tiles

 

[dormermike]

Thanks both

The detail I missed out was that this is a ground floor shower on a concrete floor. The base is raised on a frame made of 4x2. The shower is boxed into a brick recess so I've only got about 70mm beneath the 4x2 frame to inspect into.

Interesting about "behind the tiles" as that's where I'm currently thinking. Did consider cracked tray but I can't see any faults like that.

Thanks for your help, appreciate it!

 

[Wayners]

If you're stand corner to corner on the tray and shift your weight, any movement in the tray?

 

[Madrab]

You mentioned chipboard base of the tray, is this tray acrylic?

The mould patch on the ceiling, is that directly above the shower cubicle? If so chances are that just condensation.

A few pics of the installation and under the tray may help with close ups of the tiles etc

 

[dormermike]

If you're stand corner to corner on the tray and shift your weight, any movement in the tray?

None that I can see

 

[dormermike]

Came out this morning to find that the bottom of the trap is wet. In wondering if this is condensation.

Also I've taken off the shower controls to check the incoming pipes and to see if there is any evidence of a leak. I'm wondering if it's water making its way between the copper pipe and this threaded piece. Would it be worth sealing this tiny gap and behind with silicon or would plumbers mate be better? The pipe themselves look ok as they come through the wall about 5".

Edit I can now see how those brackets fix and there is indeed an olive and a lot of plumbers mate behind it lol.

 

[dormermike]

Some more photos showing beneath the shower, which has not been used for 2 days and the water is turned off.

 

[dormermike]

You mentioned chipboard base of the tray, is this tray acrylic?

The mould patch on the ceiling, is that directly above the shower cubicle? If so chances are that just condensation.

A few pics of the installation and under the tray may help with close ups of the tiles etc

Yes acrylic tray. Can't believe there is chipboard underneath it, asking for trouble!?

 

[dormermike]

Can acrylic trays become porous ?

I managed to get it pretty dry beneath the base and my telltale drip that appears on the electric cable was gone. So I ran the shower on low pressure directed into the centre of the tray and a few hours later the dribble is back.

I can't see a crack and I didn't spray it over the silicone or the tiles.

Dribble is appearing just behind the upstand in the photo.

 

[dormermike]

Still trying to work this one out. I've not used the shower in days, and it was dry, and now is wet, so clearly the water is coming from somewhere other than the tray. I think.

The thing is there is nothing at all behind that corner. Its a brick wall. There is a waste pipe on the other side of the wall, but its at a lower level than the timber work here which is damp. The cable shows a dribble again, despite being dry for a few days.

There are pipes above the ceiling void above the shower tray but even those are not directly above this (unreachable) corner. I was hoping this was condensation but that seems unlikely as i've had the underfloor heating and towel rads etc on.

I just can't figure out where this water is coming from. Right hand side of photo is the exterior wall. All the render, guttering, etc looks good. Freshly exterior painted, 5 months ago. The rear of this photo is a brick wall and the other side is a small utility room with incoming water main (no leaks) and a gas boiler, and the aforementioned soil pipe.

Anyone got ideas please?