spotty damp patches on chimney breast

[tryeraspanner]

Hello,

I have a bungalow where the lounge has been divided in half to make 2 bedrooms. The new partion wall joins the chimney breast (fireplace has been bricked up).

In one bedroom there are 5 or 6 small damp looking spots on the chimney breast up to about the size of small saucers. The spots are clustered at chest height and spread over about 2 square feet. They fade but return in damp weather (bedroom window is generally left open a crack all day).

The chimney breast in the other bedroom is fine.

Is this more likely to be salts etc coming through from the chimney insides rather than penetrating damp?

If salts, can i just paint a sealer over them then paint over the top of sealer?

Many thanks for all help.

 

[maltaron]

The flue needs venting. When bricking up a fireplace it is necessary to fit an airbrick or "hit & miss" ventilator to allow an air flow up the chimney. ( a less conspicuous answer is to vent at floor level thro' the skirting) The fact that this is only in 1 one room indicates that the flue swings across from the centre fireplace to one side of the breast. This is normal.