Damp patches on chimney breast.

wazza99

As in the picture 1960's semi, chimney is unused, capped and has vents in each room. The same chimney feeds both bedrooms. The used bedroom has these patches, circular in shape then water seems to drip/run down, the unused bedroom does not suffer , neither does the room below the affected one. My gut feeling is its condensation but as to why circular and random patches no idea. What do you folks think ?

stuart45

Looks like moisture running down one of the flues. 
Have you got any external photos?

grumbler

wazza99 said:

My gut feeling is its condensation but as to why circular and random patches no idea. What do you folks think ?

I'm sorry for stating the obvious, but you did check the chimney in the loft, didn't you?

Alnat1

Hubby (ex-damp proofer) asks if the chimney was clean before it was capped.

He says if there was lots of soot, it can hold moisture and this might appear at the surface in the warmest room. Should eventually dry out if there's no other source of water getting in somewhere

wazza99

I don't believe the chimney is lined, but ill double check. I'll go in the loft and have a look, i think the chimney splits in the loft to feed the front and the rear of the house, if my memory serves. I couldn't say if it was or wasn't cleaned as my son has only owned the house 8 months. Thanks all for comments.  Ignore my crap design skills but this is the layout, vents in bedrooms, electric fires in lower rooms, damp shown by red circles, so just one room affected, ps this is the adjoin wall to the semi next door as well.

MikeJXE

It don't look like damp to me, it look like water has got in at the high point and ran down the wall.

Have you checked for leaks, pipework above or roof flashing round the chimney ?

wazza99

Been down today for investigation. Loft is dry as a bone, no evidence of any leaks or any gaps in flashing etc. Chimneys are capped and not lined. I opened up the vent in the bedroom to get access to the chimney inside. Clean no soot, good draught.
Oddly though all the patches are on the left side of the chimney and not even in the chimney cavity the left 18 inches are solid brick and only on that is damp patches, none as far as the cavity or the right side, im completely confused as to why, even if it is condensation why only the left side ? ive edited my crappy picture to show what i mean

stuart45

The brickwork on the left probably contains the flue from downstairs.

wazza99

stuart45 said:

The brickwork on the left probably contains the flue from downstairs.

No the chimney goes all way down to the ground room i can see the top if the fire (electric)| the house has no flues/liners.

MikeJXE

Perhaps is was something on the wall prior to painting and it has worked its way through, I do know a water stain can do that through emulsion 

wazza99

These are a few more pics i took, really strange appearance patterns on what as far as i can tell is solid brickwork, the chimney cavity does not extend into the "damp areas"