Damp Concrete Floor - Leak?

[confusedRMN]

Hi,

We recently pulled up the vinyl floor in our fairly recently bought house and found this very damp mouldy concrete below. We may have noticed this sooner had the radiator pipes (buried on the concrete) not been covered up with pipe covers hiding the blue stuff creeping up the pipes from the ground (not leaking down from the radiator). The floor definitely feels a lot more damp around the middle and towards radiator than further out.

Our assumption and that of our plumber is that this is a leaking central heating pipe buried in the concrete and we have been quoted to re-pipe all the downstairs rads from upstairs (our choice rather than dig up and fix leak). We regularly have to bleed air from the upstairs towel rail so a leak somewhere is a safe bet.

I just wanted to get opinions though on a couple of things... I can see the pipes are covered with a thin black plastic and furry stuff so should have been protected from the concrete? Is a central heating pipe leak the most likely explanation? This part of the house is around 200 years old, however the whole house was doubled in size in 1985 and presumably concrete pad and central heating dates to then.

Once the pipes in the concrete are drained and not in service will the concrete dry out itself (we are using a dehumidifier) and is there anything that will need to be done to it, or the whole thing digging up and relaying?

I really appreciate any input, this house is becoming a nightmare!

Thanks,

Stefan.

 

[JohnD]

there is certainly long term damp. However the green marks suggest to me that the water is too far above floor level to be coming from the floor. I think it is coming from the radiator valve connections. Have them taken off, cleaned and remade with PTFE tape or some other modern method, including the tails if there is any sign of weeping. If I turn out to be right this will be much easier and cheaper. Examine around the valves with a torch and mirror to test my idea.

I would actually fit new valves, but sometimes when the pipes are concreted in, there is not enough play unless the new valves are very close in size to the old.

 

[confusedRMN]

Hi, thanks for your reply. I have had another look but can confirm there is definitely no leak coming down from the radiator valves. The pipework at the top of the pipes is totally clean all around by a good 3cm left and 5cm right. The concentration of blue stuff on the pipes is very much at the concrete level. Is it worth me chiselling away around the pipes to have a better look?

Regards,

Stefan.

 

[JohnD]

You can if you want, but a pipe buried on concrete might be leaking anywhere along its length.

I find it curious that the watermark seems to be centred where the pipes come up. I wonder if it is copper attached to plaspipe. I suppose you might be really lucky and find a loose joint as soon as you start chipping.

 

[confusedRMN]

Having a more thorough look I can see that actually the different concrete (probably seen better in these pictures) is most likely the channel the heating pipes are in that go round past the front door and into living room (unfortunately not possible to look at concrete floor in living room as laminate flooring is down that I can't lift). This would suggest that the heating pipes have been installed after the concrete so either a previous repair since 1985, or in 1985 when the house was renovated and extended the heating was cut into existing concrete floor which could date back to god knows when... meaning possibly no dpm and maybe not a leak?

The dampest patch, by feel is in the middle of the floor but I'm now assuming the pipes run along the outside where the different concrete is?

I would hate to spend money getting the heating re-piped if I didn't have to!

Regards,

Stefan.

 

[Nige F]

existing concrete floor which could date back to god knows when... meaning possibly no dpm and maybe not a leak?

The dampest patch, by feel is in the middle of the floor but I'm now assuming the pipes run along the outside where the different concrete is?

I would hate to spend money getting the heating re-piped if I didn't have to!

You are right in your assumption - that different concrete will come out easily with a hammer and chisel and expose the pipes . You are more likely to have a dpm than not . So keep calm and carry on post us a pic. of the exposed pipes - do different parts along their length and look for water.