damp stained lounge carpet - concrete floor

homerhotspur

Over the last few months we have notice random dark stains on our lounge carpet, not near the radiators, in different parts of the room. We initially thought it must be down to some unnoticed dog weeing or just general grime from shoes etc and have used a carpet cleaner several times. This seems to help for a while but then the stains have reappeared. Having decided a new carpet is needed, I thought I should first undertake some investigation as best as possible.
This morning I have managed to pull back a section of carpet to reveal clear signs of damp staining on the underlay and underside of the carpet, but no sign of actual water/moisture on the floor underneath (which is covered in lino type vinyl tile squares.)

Any ideas what could be the cause and what we should do /what type of tradesman or expert to consult re this problem would be appreciated.
Many thanks

subjecttocontract

How old is the house ? Is it a suspended floor ? Is there a dpc ? Is the surrounding outside surface at least 2 bricks below the dpc ? Has there been any recent flooding or waterlogging of the garden around the house ? Is there a leak from above ?

ThisIsWeird

I guess it must be coming from above or below, and you've seemingly eliminated above. Unless it is one of your dawgs.

See if the damp patches align with the joins in the vinyl tiles - that's where moisture could seep up, between them.

Cause? I guess the most obvious will be a failed CH pipe - do the patches form any sort of sequential line?

Or, it could be a breached DPM. How old is the house? Are the concrete floors original?

Does your boiler have a pressure gauge? If so, has the pressure changed?

homerhotspur

House is 27 years old, Barratts new build house on estate. I assume DPC issues should have met the modern requirements? No flooding etc.No visible leaks . Patches very random no real lines , more like big soaked up puddle type patches with rough edges. Dog pretty much ruled out now.

ThisIsWeird

Are you sure it's a solid concrete floor, or could it be a suspended concrete type? The latter certainly shouldn't have DPM issues as it won't have one. As I understand.

Looking more like a leaking CH. Does your boiler have a whatsit?

stuart45

If it's block and beam there should be air bricks around the external at a low level. 

grumbler

ThisIsWeird said:

Are you sure it's a solid concrete floor, or could it be a suspended concrete type? The latter certainly shouldn't have DPM issues as it won't have one. As I understand.

Do you mean beam&block? If so, it it does have a DPM.

homerhotspur

Thanks everyone. Starting to get into unfamiliar terms for me now but I've just found the NHBC card from December 1996. This states the ground floor construction is Concrete rather than suspended concrete if that clarifies. No air bricks visible.

homerhotspur

whaThisIsWeird said:

Are you sure it's a solid concrete floor, or could it be a suspended concrete type? The latter certainly shouldn't have DPM issues as it won't have one. As I understand.

Looking more like a leaking CH. Does your boiler have a whatsit?

what is a whatsit?

FreeBear

homerhotspur said:

whaThisIsWeird said:

Are you sure it's a solid concrete floor, or could it be a suspended concrete type? The latter certainly shouldn't have DPM issues as it won't have one. As I understand.

Looking more like a leaking CH. Does your boiler have a whatsit?

what is a whatsit?

Pressure gauge - Modern sealed boilers will have one, and should read somewhere around 1 to 1.5 bar in normal use. If your boiler is losing pressure, that indicates a leak somewhere in the system. If your CH pipes are running through the concrete floor and are copper, there is a chance there are pin hole leaks. Cement eats away at copper very slowly, and 25 years is about the time when problems start to occur. If it is a leaking copper pipe, tracing and fixing the leak is going to be expensive and messy. A short term fix might be to dose the system with Fernox F4 which might seal a leak for a year or two.

homerhotspur

FreeBear said:

homerhotspur said:

whaThisIsWeird said:

Are you sure it's a solid concrete floor, or could it be a suspended concrete type? The latter certainly shouldn't have DPM issues as it won't have one. As I understand.

Looking more like a leaking CH. Does your boiler have a whatsit?

what is a whatsit?

Pressure gauge - Modern sealed boilers will have one, and should read somewhere around 1 to 1.5 bar in normal use. If your boiler is losing pressure, that indicates a leak somewhere in the system. If your CH pipes are running through the concrete floor and are copper, there is a chance there are pin hole leaks. Cement eats away at copper very slowly, and 25 years is about the time when problems start to occur. If it is a leaking copper pipe, tracing and fixing the leak is going to be expensive and messy. A short term fix might be to dose the system with Fernox F4 which might seal a leak for a year or two.

Thanks , this sounds quite possible if somewhat depressing. We had a similar situation with my parents' bungalow a few years back but that was floorboards, not concrete, and still a huge job.
So, we would need to turn the CH on and then read the gauge?  I don't actually know if the pipes are copper and are running through the floor but must be quite likely I assume. If it is a leak of this nature, it must be several  separate leaks though as there are probably 3 or 4 distinct damp areas dotted around the room not connected to each other.