Damp Problem - 1970's built end terrace property

[GS69]

Hello all,
I've recently started to have an issue in my house. I'm fairly clued up when it comes to these things but this one has thrown me a bit.

Basically have dampness rising at low level around 3 rooms in the ground floor of the property, this is on internal face of the external walls. These walls are a mixture of dot and dab and solid plaster (cavity wall construction).

The floor is a concrete slab with bitumen and marley floor tiles.

I have had a specialist company sent by the Insurer who have carried out a "leak detection" which they used all types of equipment but the outcome was inconclusive. They couldn't find any leaks on the mains pipes, central heating pipes or above ground waste pipes. The water is metered and there is no movement on the meter. They carried out a salt test which found traces of chloride but no nitrates.

They next sent a drainage company who checked all the drains including up to where the soil pipe meets the above ground connection in the kitchen.

They are now telling me this is a damp issue and not covered.

I'm completely stumped as to where this is coming from? I wouldn't have expected the Marley tiles and bitumen would have been the DPM for a property of this age? Am I right in thinking that?

The only other thing I could think is it is condensation - but it's not really the time of year for that??

Any advice welcome.

Thank you

 

[Burnerman]

I would have thought that this would have already been considered, but is the DPC visible on the outside wall, i.e the ground outside isnt too high, and there's no water splashing from leaking gutters and the like above the DPC level?
Ideally the cavity should prevent this but they can be easily blocked by cement debris.
It could also be worth spraying the outside wall with Waterseal or similar.
John

 

[GS69]

I would have thought that this would have already been considered, but is the DPC visible on the outside wall, i.e the ground outside isnt too high, and there's no water splashing from leaking gutters and the like above the DPC level?
Ideally the cavity should prevent this but they can be easily blocked by cement debris.
It could also be worth spraying the outside wall with Waterseal or similar.
John

Cheers John, yes no signs outside of any DPC breaches, also no signs of dampness on external leaf of brickwork. I can only think it might be condensation? Or maybe DPM failure? Confused!!

 

[tony1851]

Bitumen dpm on concrete quite common in properties of that time.
If it's in three rooms, unlikely that the dpm or dpc has failed.
Could still just be condensation. Have you changed anything of late, such as method of heating, ventliation (or lack of it), new appliances etc?

 

[GS69]

Bitumen dpm on concrete quite common in properties of that time.
If it's in three rooms, unlikely that the dpm or dpc has failed.
Could still just be condensation. Have you changed anything of late, such as method of heating, ventliation (or lack of it), new appliances etc?

Not changed anything at all. Seems strange - there are high moisture readings throughout - high enough to suggest a leak but none have been found? The salt test didn't find any nitrates either so wouldn't that suggest it isn't groundwater?