Leak or condensation?

[dormermike]

Trying, still, to resolve a leak beneath a shower. It was leaking badly and have resealed it all including bits that were poorly fitted, but still an area of timber beneath the shower tray continues to be soaking. It's almost like it's saturated with moisture coming *through* the 2x4 timber which supports the shower tray, and is screwed into the wall which is an external cavity wall.

Apart from the shower tray immediately above that timber there are no pipes that could be responsible. On the ceiling above the timber there is a odd patch on the ceiling. I'd presumed this is condensation but now I'm wondering if it could in fact be a leak.

Does the photo pattern show more like condensation or a leak? Condensation I would have expected to be darker, leak I would have expected more widespread. Drilled a hole and the plaster was dry.

Ceiling construction is plasterboard - 100mm celotex - void - original ceiling - 100mm rockwool - void and central heating pipes - 18mm chipboard. Above that is eaves as it's a bungalow and that's a downstairs shower.

Incidentally the timber is screwed into the wall which is a cavity wall and the timber itself bridges the DPC. We had a lot of rain last night and the shower wasn't used. The timber was wetter this morning than yesterday so if I rule out a ceiling void leak, it's time to open up the cavity I think.

Thanks

 

[terryplumb]

Have you taken a look in the loft to see if there is a leak above ?
Water under the shower tray is almost certain to be from enclosure / tray etc.

 

[dormermike]

Yep I've had a look under the 18mm chipboard above the shower and there is no sign of a leak.

These ceiling marks correspond exactly to the wet timber.

I agree it's a remarkable coincidence if it's NOT the shower but I've been trying to fix this for weeks and weeks, and even gone a week without using the shower, dried out beneath with a fan, and the water reappear.

I'm convinced at this stage it's not the shower enclosure as those leaks are now resolved but this remaining leak is either penetrating damp from the cavity or central heating leak.

I just don't want to go ripping it all out.

Seems odd this ceiling mark is exactly corresponding to the wet timber.

I've got a new borescope camera coming this weekend and intend to drill into the ceiling above the damp to take a look, and also through the external wall.

Adding photos beneath tray, shower not been used for 2 days, was dryer yesterday than today.. as you can see it's soaking in the far corner but the foreground timber is dry.

 

[terryplumb]

Is your central heating sealed / pressurised ,or fed from a small tank in the loft ?

 

[dormermike]

Fed from a small tank in the loft, gravity fed open vent. Its feed/supply is turned off. Now, interestingly, there is a radiator which is the loop rad which is never supposed to be turned off, and I have to bleed it every 2 weeks. Always have, in 13 years in this property, whenever the CH is on (but never for just DHW). I presumed the expansion pipe is investing air because the level in the header never drops (hence it's supply feed is off).

I bled it yesterday, and it needed bleeding again today, approx half litre of air. The header level hasn't dropped though.

 

[terryplumb]

If you have a leak on c/ heating pipework,the level in the F&E would drop, albeit may not be easy to tell it has dropped.

 

[dormermike]

Yeah, partly why I've got the feed turned off. The amount of water that has been appearing under the tray would suggest to me the FE tank would have emptied by now, it's only about 40mm deep anyway.

What do you make of the wet timber? To me it looks saturated. If it were a simple leak it would be more localised I think unless there is a header of water above it.

I've even had a thermal camera under there and the water is same temperature as surrounding materials. If it were CH maybe it would be warmer, was my thinking.

 

[terryplumb]

Your pics (of timbers) show clear signs of water pathways on the plaster ,below the horizontal timber, so water has ,at some time , been running downward on the plaster ,not through it. Are the water supply pipes to the shower valve buried in the wall that the water marks on plaster are visible ?

 

[dormermike]

Yeh I see those, but can't reach them to see if they are dry or wet.

The supply pipes are approx 1m away on the opposite wall, the bottom of which is bone dry. I have also removed and checked and replaced them in any case and they had no evidence of leaking.

This shower was installed approx 5 years ago and had been installed incorrectly as it was leaking since day one. I've fixed those issues, incl the trap installed at an angle and sealed up with half a tonne of sealant. I do recall before this shower was installed having a hard time getting the old shower to seal but I don't remember the exact issue but am wondering if this issue is a pre existing situation and hence looking at penetrating damp etc.

Got a endo cam coming, which may help. I've already used one above that shower and found no leaks but it broke, so have ordered a new one.

 

[dormermike]

What do folks think about the ceiling. It's an odd pattern for a leak, but not exactly what I'd expect for condensation either ? I can't see behind this ceiling as it is a lowered ceiling but the one above (original one) is bone dry. This ceiling was lowered to put 100mm celotex on the bathroom ceiling.

 

[terryplumb]

If you can take a picture in close frame ,rather than from a distance it would show us more clarity.
It appears to be lots of small spots ,in a random pattern, in small areas. That's more akin to condensation, a leak would leave more of an unbroken area as it spreads, if your with me.

 

[dormermike]

If you can take a picture in close frame ,rather than from a distance it would show us more clarity.
It appears to be lots of small spots ,in a random pattern, in small areas. That's more akin to condensation, a leak would leave more of an unbroken area as it spreads, if your with me.

Thanks, have attached a closer picture. I think it's condensation but it's remarkably similar in shape and size to the area I'm trying to solve which is directly beneath, underneath the shower tray. But that would require the moisture to be travelling down behind tiles. Is that possible? They are stuck to plaster - surely it would turn to mush and they'd fall off?

Have also attached a photo from the other side of the wall, a different room (utility) which is the back wall of the shower and it's not even next to the worst of the wet under the shower. Really odd.

The 40mm pipe is the bath outlet and the wider angle is the incoming water main. The wall nearer and nearest the external wall / main is dry.

Have discovered a velux leaking slightly which is directly inline of the rafters but 2 metres away from the wet ceiling, so not directly above. The water would have to be running down the roofing felt on the tile side and then pouring down the exact right place. There is no evidence of this. Just a few drops on the felt right below the velux.

Endo cam should be here tomorrow then I'm going to inspect in the cavity behind the worst of the damp. After that I'm thinking it's time to start ripping it all out.

 

[dormermike]

I drilled into the ceiling and its all dry so i guess its condensation.

Is it possible i've got an underground spring appearing under my shower cubicle lol.