Wet underfloor, wet wall, no leak detected. What next?

Teatime99

Homeserve guy says no leak detected, has checked water meter and also neighbours water meters on either side. So what is causing the musty wet earth/rubble under my floor and the wet wall and crumbling skirting above it? Would rising damp come on so suddenly? Had a tiny leak at the stopcock repaired last December, apart from that it's always been bone dry under there. There are no fireplaces on this (party) wall.

Since this isn't a water pipe issue as I first thought, obviously my Homeserve policy won't cover any further investigations. So who do I go to now? Is there anything this could be other than rising damp? I don't want to pay a lot of money for rising damp treatments if there's a chance this could be something else. But obviously, I do need to stop whatever it is before it causes more damage to my property. 

Thanks.

Ozzig

Based solely on watching Leakdetective videos, my first question would be when all the taps etc. are off, is the water meter still running?

Teatime99

This caused a bit of confusion at first, because the original water meter wasn't working (waiting for a new one from Thames Water). But the Homeserve guy attached his own water meter and no... it doesn't move when the taps are off. 

FreeBear

Some questions for you...

Age of the house ?

Lead or plastic water pipe ?

Location of downpipes & drains ?

Has the water/soil been tested for chlorine ?

Some photos of the affected area (outside & showing the extended area).

Teatime99

It's a late 1800s mid terrace, lead pipes, there is a downpipe right beside the front door that directs rainwater into a gully running away from the house. This has obviously been happening for some time... well before the downpours we have been having recently. The water and soil have not been tested for chlorine. The Thames Water man is coming back tomorrow to put in a new water meter. Is that something he would be able to test for me?

Images show wall above problem area and what can be seen under the floor when a floorboard is lifted. I had originally assumed a the stopcock would be the source of the problem.

FreeBear

I'm seeing copper pipe with quite a bit of verdigris on it - This could be the source of your damp. Lead can also corrode if in contact with cement.. The Thames Water engineer should have a chlorine test kit in his van. Don't know if he can use it to test the damp soil, so best to ask (after offering tea & biscuits). He should also be able to do a pressure test of the pipework which may reveal the presence of a leak. In the long term, it would be a good idea to have all the lead pipe replaced, but this may not be practical.

What ever you do, don't call one of these damp treatment companies - They will try to sell you chemical DPC injections and slap waterproof render/plaster on the walls to a height of 1-1.2m. Whilst this work will mask the problem for a few years, it won't cure it, and you will have wasted several thousands of pounds in the process.

Teatime99

Thank you, FreeBear. Your second paragraph is exactly what I am worried about.

The Homeserve person who came on Tuesday was adamant that there was no leak; he tested with his own water meter. He couldn't suggest what my next step should be and seemed as baffled as I am. I will ask the Thames Water engineer when he comes to fit the new meter, but suspect that if he fits the new meter and agrees that there is no leak that will be the end of his responsibilities and he will be off!

ThisIsWeird

You say it's always been dry under there. Could you be more specific? How often has this been checked in the past? And at all times of the year?
A bit confused by the pipes connected to the stopcock. Which way does the MDPE go? If to the supply, then why is there still some internal lead pipe? If ext, then why is MDPE used for the internal bit, and not normal 15 or 22mm pipe?
On a connected issue, are all your floor vents breathing well?

twopenny

Is this an internal or external wall?

It looks very like what happened to me. Dripping overflow, rendering at end of guttering disolved and it seeped into the brickwork.
Popped out around skirting and lower plaster in patches just like yours. Earthy smell too.
All hidden until damage had been done.
I repaired it myself. Not fun but easy enough.

The drip cost £8 to repair. I've learned not to leave these things now.

FreeBear

Teatime99 said: The Homeserve person who came on Tuesday was adamant that there was no leak; he tested with his own water meter. He couldn't suggest what my next step should be and seemed as baffled as I am. I will ask the Thames Water engineer when he comes to fit the new meter, but suspect that if he fits the new meter and agrees that there is no leak that will be the end of his responsibilities and he will be off!

Thames Water's responsibility stops at the meter. Beyond that, pipework & internal stopcocks are your responsibility. However, some of the utility engineers are helpful and will test pipework if asked nicely. Ideally, a pressure test needs to be conducted which can take time to set up & conduct.

Teatime99

The Thames water guy confirmed no leaks and pressure test was OK. He was only coming to fit a new water meter, but was very chatty and helpful so agreed to have a look at the pipes for me. No faults found. The vents are all open and clear, and the pipe isn't sweating or anything like that.

When I say it's always been dry under the floor before, I mean whenever I've lifted the floorboard to turn the stopcock on and off for any reason, so maybe hmmm... once a year or so.

It's now looking like the water is coming in from somewhere else, so I'd better go and investigate that now. 

Thanks for your help, everyone.