Damp caused by leaking pipes?

[jmaxwell]

There are two locations in my house where damp is occurring near to copper pipes. I have an intuition as to the cause in each case, but I'd appreciate a second opinion from you more experienced chaps before I call in a plumber.

1: Salty efflorescence emerging from the plaster (wallpapered over it, but the paper is being pushed off by salt crystals), and green deposits on the pipes. My guess is that there's a small pin-sized hole somewhere on the back side of the pipe itself, and new run is needed.

2. Damp patch on an exterior wall. My intuition is that it's rising damp, causing the pipe nearest the source to go greenish, rather than a leak from this pipe?

Any thoughts would be much appreciated in tackling these small but persistent problems.

 

[garyo]

Have you ruled out moisture from your house condensing on the pipe and making the walls damp and/or pipes corrode?

 

[drpepe]

As above - I would look at condensation, especially as it is an external wall.

 

[jmaxwell]

In the case of the first, the wall here is interior and the damp patch/efflorescence is very localised. From looking at the damage to the wallpaper, it seems moisture is running down away from the pipe. How common are pinhole leaks in copper pipes in straight runs?

Edit: The first is a bathroom which gets humid when in use, but the second is a bedroom under sink cupboard, so there is not any moisture in the air.

 

[Newboy]

In the case of the first, the wall here is interior and the damp patch/efflorescence is very localised. From looking at the damage to the wallpaper, it seems moisture is running down away from the pipe. How common are pinhole leaks in copper pipes in straight runs?

Pinhole leaks are not uncommon but you would be likely to see running water and (with good hearing) may be able to hear water hissing from the pipe. What are the pipes connected too - central heating, hot/cold water supplies?

so there is not any moisture in the air.

There is always moisture in the air!

 

[jmaxwell]

Pinhole leaks are not uncommon but you would be likely to see running water and (with good hearing) may be able to hear water hissing from the pipe. What are the pipes connected too - central heating, hot/cold water supplies?

The pipes are connected to the cold and hot water supplies, fed by the header tank and hot water cylinder.

There is always moisture in the air!

I meant that as it is a bedroom, there is no activity in the room that would cause an unusually high level of moisture in the air, as you would typically find in a bathroom or kitchen.

Edit: The pipe in the second photo actually has a spur, about a fifth of the way up, that goes through the rather thick wall behind and into the kitchen. On the other side, it sticks out of the wall but has been cut short and terminated – it no longer supplies anything. So the spur that goes through the wall could have some kind of leak, that's not visible or audible?

 

[Newboy]

The pipework you have described will probably be low pressure and it's unlikely that you would hear water escaping. Is there any play in the pipework that would allow them to be pulled slightly away from the wall?
If possible you could get a piece of tissue behind the pipe, below but close too the affected area.

The blue salts visible in your first photograph suggest that the copper pipe is corroding - possible in contact with cement/plaster.

The bedroom pipework - condensation forms of cold water pipework readily, especially at this time of the year with cold water in the pipe and high relative humidity in the air. Try running the cold tap for a few minutes, leave it for 10 minutes and try wiping the pipe with tissue to see if there is condensation of the pipework.

The section of pipework close to the floor looks as if it might be getting damp from the surrounding wall as the entire area looks to have some sort of damp problem.