Damp patches concrete floor

[Decca2]

The internal mains stop-cock is located in the hall ~6m from the damp patch.

After wrapping every water-pipe joint in the garage with paper towel and seeing no sign of dampness, I'm now 99.9% sure that the source of water is below the garage floor.

I made a close inspection of the edge of the concrete garage floor but did not find any sign of a membrane coming from under the concrete to meet with the wall dpc, which is about 1" above the concrete, therefore, I now believe that water is wicking up between the wall and edge of the concrete, then spreading out through the concrete from that point. The challenge now is to find the source of the underground water!

Operations are now suspended for a week until our guests leave but I then intend to chisel out an inspection hole in the dampest part of the floor.

I'll report back on what I find.

 

[JohnD]

drain water and rain water is more likely to drain away than to rise up, but a leaky water main is under pressure so more likely to come upwards, especially if it is laid abover oversite and below floor. The pressure will drive it to find an escape route.

the tests I mentioned, especially the glass of water and the kitchen tap, will tell you if there is a leak downstream of the external stopcock

 

[bogwort47]

At last, I have just overcome the curse of the Newbie - I've found your pics.

I agree, the most likely cause will be the pipes on the wall and/or possibly the boiler, which I'm guessing is on the same wall. It is difficult to see but unless stand offs have been used to keep the pipes away from the bare brick wall, or more particularly the mortar, then there is a risk of pin holes developing in the pipes - more so if you have a boiler in the same space along with a cold water feed pipe - you will get condensation which will increase the problem.

Please do not start digging up the floor until these pipes have been released from the wall and thoroughly examined.

I note that there is also a potential drainage problem in front of your garage - the green! I wonder where that water goes.

Thanks for the PC will have a look at the w/e.

Hope you have a good week with your visitors.

 

[bogwort47]

Hi

Thanks for trusting me with your Post Code.

I believe I've found your house - it is part of an 'L' shaped block with a green area enclosed to the rear on 2 sides - yes?

I have checked the lay of the land around your house as best I can see on Google and there are some possibilities but all much less likely than the pipes on your party wall - so I won't go into details at this point unless all else fails.

One question has come to me though - prompted by another contributor relating to loft condensation. Is washing dried in the garage? If so, at least 1 of the pipes on the party wall will be a cold one and given the presence of what I think may be a set of boiler pipes, unlaqgged, then conditions will be ideal for condensation as the cause.

Failing that, though less likely, is just natural condensation - unless there is a hidden source of water - least likely perhaps.

Most likely though, remain the pipes on the party wall. I think you have some stains on the wall perhaps from your pic.

Please, I suggest that the wall pipes and drying washing are eliminated
first.

My best to you, Adrian

 

[Decca2]

Saga continued.
Just back after few days away. The water meter readings on return was EXACTLY the same as when I left, i.e. zero consumption! BUT the garage floor is still damp, even after the 3 hottest days so far this year.
Last Tuesday it started to dry out but was damp again Wednesday.
Have since learned that the neighbour on the NW side (garage ~20ft away) occasionally gets damp patches in his garage and suggests that if and when mine dries out I coat the floor with a sealant.

CONCLUSION: there is a new underground source of water that, at the moment, is only affecting my garage floor, therefore it must be being channelled there from a source external to my town-house.

QUESTION: is it possible to trace underground water pipes using a metal detector?

 

[JohnD]

you haven't yet tested for a leak as I described? it really does work

how much water do you have to run to register on the meter?

 

[bogwort47]

Based on the premise that my water meter is similar, the slightest dribble/drip will register on the spinner. I suspect that the glass test may be more sensitive oner a period of time though the pressure in the system will only be the house head of water as opposed to mains pressure.
Given the degree of dampness seen, I would suggest that the water source is more significant than an odd drip.

To this end, I feel it would be prudent to eliminate acid leaching of the pipes on the wall and condensation from washing or the interaction of warmed air from the boiler pipes/boiler on the cold water feed pipe running along the party wall.

It will be difficult to help you further without this feedback.

 

[Decca2]

Sorry guys for delay in updates but I've been away on business and I'm rather tied up at the moment.

Can definitely confirm that there is NO internal leak or condensation in the garage or boiler room.

In July I plan some holiday and will turn off the water supply at the street stop-cock and drain-down the house cold-water system.

Would still like some advice about whether or not an underground leak can be detected with one of those electronic tracers used by the water companies?

 

[bogwort47]

Thanks for the update.

I know nothing about the test method you mention - perhaps JohnD can help. I still use a hazel stick and eye.

Anyway, if nothing is showing on your water meter spinner with all outlets turned off over say over 5 mins it is very very unlikely that your water system would produce the extensive wetness in your pic.

You have stated that there is absolutely no condensation on the cold water pipes or pin hole leaks in the pipe work on the party wall. You have not mentioned washing, so I must assume that you have included that in the general statement of 'no condensation' - this is very unusual though.

So the most likely source is now ground water from:

1) the water main in the road - road appears higher than you

2) road drains leaking - from Google there has been at some time quite serious flooding because of blocked road drains on your side of the road beyond the trees/bushes. This water will have entered the ground and will take months and months to dry out.

3) watering by your neighbours perhaps across the road where the ground is higher.

4) the soak away outside your garage we already know is not clearing the run off from your drive - is this the cause or just part of it? It really does need fixing.

From my own recent experience, just because the weather has been dry for a while doesn't mean that water which may have collected under your house has gone - in my case it has taken months not to dry out.

My best advice is to contact your water board and say you have a problem which you do not understand and ask them if they can checkout the water supply main and road drains. The sooner this is done the better because the longer the problem exists, the more costly the costs to the water board to make good any damage to your house equally your insurers will not be best pleased if you fail to take prompt action. If you have problems getting the Water Board to act get your insurers involved to help - notwithstanding you may need them if your drive soak away needs major work. I think you said that you had only recently moved in - was there anything in your survey report about any of this?

Good luck and please keep me posted - if the road drains are still as shown on Google, you should prepare yourself for the possibility that the problem has already been reported and no action has been taken by them. Try asking your neighbours about any problems with the road drains first.

 

[Decca2]

Interesting observations and food for thought.
Here are some more facts:
1. After a prolonged dry-spell the garage floor has almost completely dried out!
2. The road gutter is about 19m from the garage, down a worn macadamed drive.
3. Using a laser-level, I've measured the road-gutter at 160mm lower than the garage floor (I presume the road drain is about 1m lower still).
4. The houses opposite are, if anything, lower than the road.
5. The floods we had 2-years ago were about 150m further down the road, towards the main drain.
6. When the guy next door washes his car outside his garage the water stands for 3 to 4 hrs because there's a slight depression there (lower than my garage floor) but he doesn't have damp patches on his garage floor!

CONCLUSION: there's no obvious source of surface water getting to my garage and it can't be a leaking pipe, otherwise the floor wouldn't be drying. Still baffled.

 

[bogwort47]

Thanks for your response to my thoughts.

Certainly some food for thought there.

I'll think on what you have said - I'm beginning to wonder if I am looking at the same thing on Google that you are. Do I have the right property? The hanging basket still looks the same.

From what I have seen on Google there is clear evidence that the road drains are not coping with the water and it is flowing over into the ground.
Take a look and see if you see the same thing.

As for your neighbour and his standing water it has to be going somewhere - where?

From Google, you have green growth on your tarmac drive to the left front of your garage - is it the same at present?

If you had floods down the road then the drains could have backed up to your location and caused a problem also. All too often, as areas are progressively built on the original drains cannot cope with the run off. I have the problem here and we regularly have a manhole lifting and the local authority has had to improve water run away to prevent a property near us being flooded.

I will be in Brum. early July, I might be able to call by and take a look - what do you think?

From what you have said , I think we can safely eliminate the water supply and main. This leaves ground water from the road drains, your roof downpipe and soakaway and the run off from your neighbour's drive as I see it.

What do you think?

Best regards.

 

[Decca2]

I've lived here 11 years without any floods or overflowing drains, so I to am wondering whether we're looking at the same images? All I can find on Google Earth is a fuzzy overhead picture of the block, where it's difficult to make out my townhouse. Could you let me know the Google pages you're viewing?

I don't have any plans showing the surface drainage around the block but water on the driveway runs into the road drains, except for a patch about 1/2" deep x 6' x 3' where my neighbour's car stands, which eventually evaporates. Even in heavy rain there is no standing water on the driveway to the front, or the lawn at the rear of the property.

Incidentally, my building insurance company were amongst the first contacted about the damp patches. They said a claim could only be made if it was 'rising damp' and they couldn't even recommend a surveyor who specialised in this type of problem. The water company say that anything beyond the stop-cock is my responsibility.