white powdery residue

[allans67]

Can anyone tell me what the white powdery residue is that is on the ceiling of the inside of my loft. It falls off easily and brushes off but returns. Is it a fungus and how can I get rid of it. Is it dangerous to breath in? Any help on this matter would be gratefully received.

 

[Deluks]

What is the ceiling made of? Plasterboard? timber sarking?

Proper converted loft?

 

[allans67]

Thanks for your reply. The roof is not made up just original joists with slate covering

 

[JohnD]

scrape some into a saucer, pour boiling water on it, see if it dissolves but recrystallised as it dries out.

do you live near the sea?

do you get white deposits on the brickwork as well?

 

[allans67]

The white powder is very fine like chalk dust.There is none I can see on the brickwork .The powder dissolves quickly in the boiling water seems to be no crystal formation. We are some two miles or so from the sea at Kintyre did you think it could be salt?

 

[JohnD]

if it dissolves it is probably mineral salts.

spray carries a long way in storms. Don't your windows get hazy? Taste it.

Let the saucer dry out and see if it recrystallises.

 

[allans67]

there does seem to be a fine streaky crystal structure on the dried out sample perhaps slight salt taste, our windows on occasion have had sandy or powdery deposits on them. I just worried about breathing this stuff in up in the loft and whether some treatment was needed. It seems it might be salt deposit so should be ok? Anyway thank Deluks and to you JohnD for your interest and all your help..