External damp (?) patch

[Elroch]

I have a mystery to solve. I live in a first floor flat in a 3 story building built in 1994. On the outside wall is a elliptical dark patch, almost 1m across, on the brickwork, with my overflow pipe roughly in the centre left to right and near the top. The patch overlaps my flat and the one below. The patch appears dry to the touch but looks like it is damp. No water has been seen coming from the overflow pipe (which projects about 15cm) but there may have been some. No water has come from it recently (collector has been attached).

I (and a site services engineer) thought some water had come through the overflow pipe, perhaps in strong winds, and dampened the brickwork beneath it. The only possible cause appeared to be the header tank which has an overflow pipe entering the water vertically (anyone know why) - the water level was surprisingly near the level where the pipe turns horizontal, so I adjusted the ballcock to lower the level of water a little. Not a drop of water has come out of the overflow since.

And that would be the end of it, except the patch has not reduced much, so I am concerned that there is more here than was suspected. Have you any comments, advice or theories?

 

[Newboy]

It's possible that the overflow has been running but that as it exits the overflow it is running back along the underside of the pipe and onto the brickwork - you won't see any water falling from the pipe if this is the case.

The overflow inlet in the cistern sounds correct - there should be an elbow taking the pipe from horizontal to vertical inside the cistern.

If you have adjusted the ballvalve to stop the fill at the correct level then this should eliminate the problem

As for the damp patch drying out - it could take some time depends on how saturated the bricks are and the weather.

 

[Elroch]

Thanks for the reply, which seems spot on.

The brickwork is drying slowly (but visibly) in this cold weather. I have noticed that the overflow pipe is tilted slightly upwards, indicating a small build fault, in my opinion: if this was downward or horizontal, the water would simply fall on the ground. Although this is obviously best practice, I am not sure it forms part of a regulation or standard.

The green mark on bottom of the protuding overflow pipe confirms the water was running back along the underside of the pipe to the brickwork. As not a drop of water has come from the overflow since I adjusted the ballcock, that appears to be the end of it.

 

[Nige F]

it will be until it overflows again glue an elbow on the outside ...wish I had £ for every one i`ve seen like that