Is this damp/condensation or something else entirely???

[elainer03]

Hi Everyone,

I have no idea what this stain is.... I have read the Damp FAQS and didnt really make it any clearer.... It doesn't feel wet to the touch, its on an internal wall opposite our front door. We live in a basement flat, but we don't have any earth above our floor level if you know what I mean. I have been told by my partner that there are not any foundations as such (scary!). Its a building from late 1800's.

It just seems very odd to appear in the middle of the wall!

Any ideas appreciated...

Thanks, Elaine

 

[MdB]

Leaky pipe buried in the wall maybe?

Whats on the other side of the wall(s) from the stain?

 

[Mark]

Does it come and go or is it always there?

Is that a solid wall or plasterboard?

 

[elainer03]

I don't think its a pipe, at least i hope not. The water mains are in the room you can see on the right on the opp wall.

Behind the stain - basically nothing, our kitchen it to the right, but the sink etc is on the other end of the room...

It just seemed so odd to appear in the middle of the wall. I had thought if it was a leaky pipe or a leak from upstairs flat it would show in other areas on that wall.....

And it does seem to fade with good weather, which is completely bizarre as there is no way water from outside could get to that patch... It is a solid wall....also very thick, i did think that it may have once been the outside wall, but i have been told i'm wrong...

 

[joe1978]

I've not been around here in a bit, been really busy but...

My two pennies worth, I would'n't rule out upstairs, a small trickle leak could run down fill or between stone/brick and plasterboard and not show up until obstructed. Which could be some distance from actual leak. Some time back I posted here about a damp problem, turns out there was literally a slight drip every day from the toilet above and that was accumulating and causing the damp patch.

We noticed it by chance and fixed it then all visible damp dissapeared...so far!

joe

 

[Nemesis]

Wild guess - salts in the plaster which attract damp and then dry?

http://www.buildingconservation.com/articles/risingdamp/risingdamp.htm

Is the wall painted or papered? Has there ever been any sort of chemical damp course, or cement based render below the patch?

 

[Penners]

Did you paint the wall, or did you inherit that finish? If the former, did you notice any staining there before you painted over it?

Stains in plasterwork can be notoriously difficult to cover. You paint over them, and a few months later - there they are again! Stain Block paint can be quite effective. Put a couple of coats over the stain and then repaint the wall.

A word of caution, though. Just be very sure that - as has been suggested above - there isn't an ongoing leak anywhere that's causing the problem.

 

[Raylea]

We noticed we got two patches in one room at the beginning of last winter especially when we cook. They are high up, but we lit a real fire and it dried out and had no problem since. You wouldn't have foundations in a house that is old and its been there a long time so its not something to be scared of

Not sure if I have helped you, but rest assured you are not on your own with the odd damp patch!!
Raylea

 

[Lime]

The question that comes to my mind is, is it damp or is it some sort of oil stain grinning through the paint?
Much may depend on the original and subsequent use of the rooms.
I'd test it for damp using my high frequency damp meter (no prongs).

 

[Nemesis]

If it was something other than damp, I suspect it would be constant - as it seems to fade in dry weather I can't see it can be oil.

 

[GK]

I get patches just like that on interior walls, well above ground level, where the plaster varies in type and material, repairs with different mixes, that kind of thing. Sometimes you see them, sometimes you don't. Did you post the picture on the day you discovered it? It warmed up quite a bit that day, more moisture in the air . . .

 

[arthurw3]

My guess is hygroscopic salts in the wall, either the salts resistant plaster that should have been applied when the dpc was done has failed, or it was never put on in the first place. Hack it off and replaster that small area with BPB Drykote. The tricky thing will be doing it so that the plaster patch doesn't show thro' the wallpaper. You may be best to sand it completely level after the plaster has set and dried.

 

[PC]

As Nemisis and Arthurw3 have indicated I would tend to agree that from the discription it sounds very much like a salt issue, probably exaggerated by increased humidity levels in area (adjacent kitchen)!

If it was a plumbing leak (no matter how big or small) I would expect damp patch to continue to increase in size.

Would suggest that if this continues to cause concerns as recommended by 'arthurw3' - Hack off plaster and reinstate with salt resistent plaster, however dont just hack of area of staining, go well beyond stain, otherwise problem could well re-appear elswhere.

PC

 

[Penners]

It's probably worth adding that - I presume - the above two posts are applicable assuming that the wall is gypsum plastered. If it's lime, then I suspect the lime experts on this forum would have other views.

 

[Lime]

It's probably worth adding that - I presume - the above two posts are applicable assuming that the wall is gypsum plastered. If it's lime, then I suspect the lime experts on this forum would have other views.

Precisely.

 

[Raylea]

We have left ours, it may well return at the beginning of next winter, once the real fires go on it disappears. Can't say for two patches I want to start hacking of plaster etc. If it was getting worse then I would be considering appropriote action.

Raylea

 

[PC]

I suspect that if the wall were lime plastered the damp patch may not be quite so prominent.

PC

 

[Johneds]

This could be many things. As prev mentioned salt contamination would be high on the list. I have also seen patches like this caused by holes in the brick/block/stone stuffed with newspaper (presumably to save on dubbing out) and timber grounds.

The only way you will know for sure is to hack off and have a look.

 

[Penners]

And if it does turn out to be nothing more than a bunch of newspaper, I guess you'll be pretty hacked off.

:lol: :lol: :lol:

It's the way I tell 'em.