White Mould / Fungus On Chimney

[rosyherb]

there is a white mound / fungus on the chimney breast in the kitchen and adjoining storage area, there is nothing on the chimney breast in the rooms above, just in the downstairs. the chimney is not used and has been blocked off. Any ideas?

thanks in appreciation

R

[The Builder]

How far up the wall is it Rosy. Halfway up, or at ceiling level?

If halfway up, then the white stuff could be efflorescence from rising damp. (White crystals left over when rising damp evaporates.

Ceiling level would more likely be steam condensing on a cold surface, producing what could be "cellar fungus".

[rosyherb]

the bottom half of the chimney breast to shoulder level is tiled, and the mould is above that and it is roughly in the same place in the storage area but does also go lower. i had the house totally checked when i bought it 10 years ago and the chimney is 'mid' house not an outside wall, all the ceilings, floors and plaster was replaced as part of the renovation the house is 1890s terrace

[The Builder]

So many things to think about, Rosy.

A house ay that time would have had a fairly basic damp-proof course installed ... probably either a coat of pitch or a course of slate applied to the brick bed.
These are known to fail over time. Any rising damp would be held back from entering the room by the tiling. It's not unknown, in these circumstances, for it to rise and show above the tiled area.

No tiles, I guess, in the storage area, but, if it's a cupboard, then lack of ventilation could result in condensation/mould deposits on surface. Kitchens generate a lot of water vapour. Do you have good extraction? Do you have gas cooking?

The first, and simplest thing is to make sure the chimney flue is well ventilated top and bottom. Check this first. It may well be the cause here.

If it is a DPC-related problem, then I would suggest some remedial works involving some re-plastering, but look at the flue ventilation first.

[rosyherb]

thank you very much for the advice, no tiles in cupboard and there is a ventilation panel in the wall as the boiler used to be in the chimney, house is empty at the moment. I will get someone to look at the flue the bottom is blocked off due to asbestos lining in the flue.