Water patch on concrete floor

[SteUK]

Hi,

I am leveling part of our kitchen floor, taken up 2 layers of laminate and removed lose laminate tiles. Having slapped on some pva/water mix and left it to dry over night I have found a small pool, 30cm*30cm, of water has formed this morning. I dried it off and re-applied (thought one of the cats might have made a dirty protest despite it having no real 'cat' smell') only to find the same thing an hour later!

The concrete is covered, most of the floor, with some black compound(?).

Is this rising water potentially serious? Can someone offer some advice on the best action to take? I have the tools to chisel up the floor if need be.

Cheers!

Ste

 

[breezer]

start digging

 

[SteUK]

What am I looking to find?

As info, the pool produced (both times) was right next to, but was not up against, an outside wall. After applying the 2nd lot of pva/water it appeared to be drying, then on return it had produced the water pool. After cleaning up the pool no water appears to be forming again now...

 

[SteUK]

Some more info. 2 feet left of the puddle is an outside wall. On inspection lowest visible layer of mortar is wet and has come away/been washed away about 1cm into the brickwork. The kitchen waste pipe had been removed internally and had fallen away from the wall(!) revealing the brick and cavity insulation to the elements. I do not recall it raining but there has been dew on the ground the last few mornings (since the pipes removal). Could this have caused what I am seeing internally? Has it done any serious damage? (past some re-pointing).

Cheers!

Ste

 

[SteUK]

It appears the puddle _may_ be accumulating from where the wall meets the floor. I jammed a piece of kitchen towel into the gap and left it for a few hours and the kitchen towel is now damp with no puddle on the floor. The wall was plastered(re-skim only) yesterday.

So, in light of this new info, anyone got the slightest clue what might be the issue?

Cheers!

Ste

 

[Deluks]

A modern concrete floor will have a damp proof membrane (DPM) tied into the damp proof course (DPC), this keep moisture out of the floor. So you are either lacking either or both of these. Otherwise you could have a leaky pipe somewhere or no/rubbish guttering.

 

[JohnD]

do you know where the water main runs?

 

[SteUK]

The house is 1960s, not sure whether it has a DPM under the floor, the DPC in the wall is higher that the floor and there is no evidence of anything in between other than plaster, breeze block, brick and mortar.

The main drain is about 3 feet away but, I think, does not run past the problem area.. Saying that, the corner of the room (about 2 foot by 1 foot square - between the drain and problem area) sounds almost hollow when bashed (compared to the rest of the floor).

The water main looks like it takes a straight route out, bisecting the problematic wall about 2m away from the problematic area.

There is a gutter pipe that drops down from the roof near the problem area (1 foot along the wall outside) and this is no longer sealed into the concrete path as evidence suggests it once was. The 1-piece path runs externally along the problematic wall almost meeting it (about 1cm gap). The path has always had a crack in it and is raised slightly. This has all been the same since we moved in on April 1st.

I have a plumber coming out to hook up our new cooker on Thursday, is he the right trade to tell me what the problem is? Or do I need a builder?

Thanks

Ste

Edit: I am quite sure words are not enough and will endeavor to get pictures up tomorrow.

 

[JohnD]

a plumber is a very suitable person

it is possible fpr water mains to leak under the floor. you can sometimes hear a faint continuous hiss until someone turns off the upstream stopcock

I had this happen to me once

There is a test* you can do with a glass of water at the kitchen tap

as the water is under pressure it will try to escape wherever it can. The floor or walls may be very wet.

a leak under a floor or slab will tend to wash away the ground or loose fill leaving a cavity

*test described here //www.diynot.com/forums/viewtopic.php?p=338555#338555

I've had that too.