damp floor and skirting for no apparent reason

[lbj20]

This evening I found the corner of the downstairs loo carpet was damp. It's a corner between external brick wall, and an internal wall to the hallway. The carpet and skirting are damp along around 8 inches of the ext wall, 1-2 inches wide visibly wet, and then a narrow strip of damp runs along the internal wall for a couple of feet. The skirting as well as the carpet is damp or even wet to the touch along those sections.

I assumed the toilet was leaking but it's all perfectly dry, and the carpet under/behind the loo is also perfectly dry. There's no sign of water from above - no pipes, no damp paint on the walls. (THe room above is the bathroom). The one thing I could think of was the toilet overflow pipe which goes out through the wall just level with the end of the external wall damp bit - so maybe if that was leaking in the wall, and the leak all went one way (not spreading out evenly to either side) it could be that? Although the cistern isn't filling to anywhere near the overflow so the overflow shouldn't even be in use? (the exterior pipe is a little cracked, though, and has been for some years). It's not been raining; there's no sign of water in the hallway side of the interior wall.

So - what sort of handyperson do I need? I guess i need someone to take up the carpet and look in the first instance, and if it's the overflow, to redo the pipe/bricks???

I can't imagine it's been very wet for long but it could have been a slow leak for some time i guess that's only now visible.

thanks in advance for any tips!

[Lootman]

By any chance, is the level of the interior floor below the level of the grade of the exterior ground at that location?

If so, another possibility is that water is seeping up through tiny cracks in the floor. Obviously this would usually only happen during periods of sustained rainfall and you said it hasn't been raining. But could the water table rise above the level of your floor? Are you near a river (that's part of my problem)?

I mention this only because that turned out to be the cause of a leak that I had on the floor where it meets an outside wall, even though no sign of water ingress could be detected through the wall or from above. The water literally seeped upwards, contrary to what water normally does.

I hired a foundations/groundworks contractor. Their job requires a profound understanding of all the ways water flows can cause problems, in my experience. Of course, if this is instead a plumbing issue then ignore me.

[richlist]

Some areas to eliminate first:
* Is there a buried water pipe in the floor, perhaps a supply or return pipe for a radiator ?
* Or a mains water supply pipe ?
* Could it be condensation ? Cold weather & poor air circulation often causes damp in corners.
* Has a pet had an accident ?
* Are you certain its not an accidental spill ?
Etc, etc.

[Gaggsy]

A few thoughts:

Is it definitely water? Does it smell? Just asking in case it's a pet or someone missing the bowl

Is there an incoming water pipe in the vicinity? Try turning the inside stopcock off and seeing if the outside water meter keeps spinning - could indicate a leak on the outside supply pipe. This could saturate the ground.

Any pipes buried in the wall or floor? What is the route of the supply pipe to the cistern?

[robbelg]

I'd start by taking up the carpet and drying very thoroughly, going as far as using a fan heater or hair dryer, then laying down some kitchen roll or toilet paper.
This will quickly let you know if its coming through the wall or the floor, or if it was some odd one off event!

[lbj20]

Thanks for all the great suggestions! No pets, no pipes to rads etc, no spills, but enough wetness to be visible on the carpet and doesn't feel like it could be condensation... but the soil pipe does run out in the concrete drive outside and we think a crack there could be causing seepage upwards. We took the carpet up and it's definitely coming from below. We've got a dehumidifier running now.

So next step is a CCTV drain inspection I think - apparently that's a useful step towards a proper diagnosis and potential repair. Fingers crossed!

Thanks again

[Lootman]

Thanks for all the great suggestions! No pets, no pipes to rads etc, no spills, but enough wetness to be visible on the carpet and doesn't feel like it could be condensation... but the soil pipe does run out in the concrete drive outside and we think a crack there could be causing seepage upwards. We took the carpet up and it's definitely coming from below. We've got a dehumidifier running now.

So next step is a CCTV drain inspection I think - apparently that's a useful step towards a proper diagnosis and potential repair. Fingers crossed!

Thanks again

It took me two years to figure out a problem that was a lot like yours, simply because I could not conceive that water can run uphill and leak from the underneath. Good luck.

[lbj20]

CCTV shows no obvious issues, although perhaps back in the office with a bigger computer screen they might spot something, so waiting on the full report. The drains surveyor at least confirmed that It Comes From Below, which I suppose is good. So, possibly drains, or maybe a failed damp course?

[shadowside]

I had a very similar problem a few years ago. I thought it was a failed damproof course but it turned out to be a leak on the joint between toilet pan and soil pipe. Water then tracked along the floor joist and up the wall. Was prepared for a major repair but turned out I could just fit a modern joint connector into the old soil pipe and probem solved. Has been fine ever since.

[lbj20]

Well, CCTV of drains was all clear. I tried a surveyor next, and he's confirmed it's not the damp course or anything awful like rising damp - he thinks it's a damaged joint between loo and stub soil pipe, which is conveniently hidden in a tiled box in the corner of the house. Plumber coming next week to open it up (and hopefully fix...).

The surveyor was *thrilled* to have such a mystery