What could this stain be?

[psyjrobe30]

Hi,

I moved into a new house in September and shortly after I noticed a strange stain on the dining room wall about 7ft up (see attached). We were painting that room anyway so went over it but it has now come back gradually and is quite prominent. Any idea what this might be and what work may be required? Could this be a damp issue?

Untitled

• psyjrobe30
• 10 May 2015
• 1

 

[kingandy2nd]

Damp.

You need to give more detail to understand the cause though - whats on the other side of the wall, are they exteriors walls, etc?

 

[psyjrobe30]

It's about 7ft up and the wall on the left of the image is an exterior wall. The wall on the right is interior (newish extension on the other side).

 

[JohnD]

where's the downpipe and the bathroom?

 

[^woody^]

In that location and with that shape, it looks condensation related.

 

[ree]

Given the position and shape I'd also go for condensation but for the fact that the "stains" have been painted over and re-appeared in the last few months - thats more like "damp behavior".

The right hand wall used to be an outside wall before the extension:
are the walls cavity or solid?
any insulation in any cavity wall?
is that solid plaster or dot and dab?

Can you post pics of the exterior, and where the main house roofing meets the extension roofing.

 

[footprints]

Well the one on the left is a Sumo wrestler, and the one on the right looks like The hungry caterpillar to me!

Did you use a stain blocker? If you did not old stains tend to come through after a while.