Bedroom wall (exterior) brown powdery residue!

[ramccann]

Hi. I have a major problem on one interior wall.

I live in a 100 year old stone brick building and occupy the top (1st floor).

One exterior wall in the master bedroom, one side of which is next to a window the other a corner, is covered in patches of yellowy/brown powder from approximately 2 feet from the ground to the cornice.

The wall on the other side of the window is not displaying any such signs.

I had the felt on the roof replaced last year to try to eliminate the problem but it hasn't worked.

There is no sign of damage to the exterior of the property.

There is a problem with ventilation in the property with no vents in the sash windows so I thought it may be some sort of condensation issue, though I would have expected black residue not yellow.

I live 2 streets back from the sea and wondered whether it might be something to do with salt penetrating the brickwork.

Any thoughts, help or advice would be much appreciated.

Thanks

Rob

 

[PrenticeBoyofDerry]

Likely to be mineral salt efflorescence, the walls at some stage has become damp from external influences and the salts have penetrated through to your plasterwork.
Firstly you must cure this, it could well have been the leaking roof or pointing, dpc or external render that has failed.
Once cured the plaster will need to be replaced.

 

[ramccann]

Thank for he reply.

Is it right that salt efforvensence can be yellw/brown in colour, maybe to do with the colour of the stone?

Any advice how to treat this problem?

 

[PrenticeBoyofDerry]

Is it right that salt efforvensence can be yellw/brown in colour,

Yes, do you not believe me?

maybe to do with the colour of the stone?

Unlikely

Any advice how to treat this problem?

Already be given, solve the damp problem and replaster, maybe using dri-coat.

 

[ramccann]

It was just that the research I've done in salt effervencense after your reply says that the residue is white in colour.

I meant what chemicals or solution would you recommend to rid the stonework of salt. I've seen a product called salt neutraliser and wondered whether this would help before replastering.

Thanks

 

[^woody^]

Efflorescence is normally white due to the particular salts

Brown stains tend to be associated with chimneys, but can also appear on walls with certain mineral content eg ferrous (iron) compounds

You don't say whether the walls are plastered, as brown gypsum plasters can appear to have brown surface salts , but its just the grains of plaster powder

Whatever the salts, the cause is either a past case of water penetration which has been remedied but the salts are hygroscopic - ie absorbing more moisture from the air. Or its continuing water penetration.

Either way, after rectifying the cause, you should replaster with a salt resistant plaster or render, or seal any bare walls before redecorating.

I doubt it will be anything directly to do with salts from sea air

 

[ramccann]

Thank you both very much for the comprehensive answers.

I now feel much more confident and informed to deal with the issue when hiring a plasterer.

Best Regards

Rob