Dampness on lower wall and base

[CaptainJack406]

Hi all,

We have a small issue with the damp at the bottom of the wall in our
living room. After heavy rains (usually coupled with wind), we see a
damp patch, which dries out after a day or so. I am attaching a
picture of it.

At the moment, there is no flooring there due to unrelated work going
on in the house, so it's clearly visible. You can also see the plaster
behind the paint is (or appears to be) damp. About 1m away from the
photo, I can also see some damp on the plaster but the floor appears
dry.

Looking at the wall on the other side (it's a cavity one), there is a
lot of damaged mortar around the bricks, especially above the problem
area inside. What seems to be happening is the water getting in
through the brickwork, pooling at the bottom of the cavity and leaking
inside. I don't think it's the roof as there's no evidence of a leak
in the loft or upstairs.

It may potentially be a rising damp but I am not convinced since the
damp proof course seems intact inside and outside (I can see the
lining through the mortar) and it's about 100mm off the ground.

Any ideas?

 

[theprinceofdarkness]

what makes you think that your cavity is clear of debris?
Frank

 

[wessex101]

One of the most common causes would be debris in the cavity bridging the DPC. It will need further investigation and possibly cutting out a brick or two or use of a boroscope.

 

[stuart45]

It used to be quite common on site to cut off the DPM flush with the inner skin before laying the DPC which is said to have caused some problems with daamp in that area.

 

[CaptainJack406]

Thanks for the replies. No reason to think that cavity is free of debris. It's actually filled with insulation - small polystyrene looking balls. What's at the bottom, I've no idea.

It used to be quite common on site to cut off the DPM flush with the inner skin before laying the DPC which is said to have caused some problems with daamp in that area.

The DPM is flush with the outside wall... and actually also inside. You can see it in the picture.

 

[CaptainJack406]

Update: the issue was that there was about 10cm worth of snot above the DPC inside the cavity. It was all damp with a mixture of rising damp, as well as the leaky outside wall.

Currently, we are getting all snot removed and digging down a few inches below the DPC and installing drip trays along with vents. The inside wall is already very much looking much drier.