odd damp patches

[rother]

help
recently moved into a 1920's house the small bedroom has 3 damp patches on the inside of a external wall, inline with an unused external chimney breast.
The lead around the chimney to slate is good the chimney has what looks like an old gas cowl in place.
The 3 damp patches stay roughly the same size, donot get larger when it rains, but do not dry out, i am lost to understand what is causing them.

Many thanks

Rother

 

[Nige F]

could bee soot stains .ideally chimney needs venting top+bottom ...ther`es answers in the wiki (ithink )

 

[JohnD]

It sounds like the chimney is open at the top which is OK, but is there a ventilation hole at the bottom to allow airflow? It need not be big, a single brick with a hit-and-miss cover will do. There will usually be two flues, one for the upstairs room and one for the downstairs.

BTW if you are cutting into the chimneybreast, fit a wallsafe while you're doing it - a convenient place!

edited: Bah!

 

[rother]

Thanks John
good idea re safe

Rother

 

[Nige F]

first place I`d look.......particularly if behind an old master fake