UKC

I've been lifting the floor in the back room today to sort out a rotten timber and found that the sub floor has a layer of white powder over it, but not in the area where the damp/woodworm problem is. The house was built in 1902 and is of mixed brick and sandstone construction with the classic south Wales black coal ash lime mortar.

Anyone know what this white powder is and if I should find some to cover the bit where it's missing?

Thanks,

Gethin.

In reply to gethin_allen:

Could it be saltpeter?
That appears in cellars, so I've read in the past.

In reply to gethin_allen:

Perhaps one of the previous occupants was a coke dealer who had a surprise raid from the police and had to tip his stock under the floorboards?

In reply to gethin_allen:

Even if Olaf is wrong you could probably still get £20 or so for it on wind street on a saturday night...

In reply to Lusk:

Hang on, isn't saltpetre the active ingredient in explosives? Just sayin.

In reply to csambrook:

It can be, potassium nitrate us potentially dangerous. I doubt it is this though as it is hygroscopic which is the last thing you'd want under the floor.

In reply to gethin_allen:

Is it not just mould?
jk

In reply to jkarran:


This is one of the few things I can discount as fungi are my specialists subject.

In reply to gethin_allen:

Efflorescence would be my guess. usually comes from brick.

In reply to daWalt:

Good point, my attic is full of this where it blows off the chimney bricks. I suspect the subfloor would be too were it not flooded.
jk

In reply to gethin_allen:

Some people used talcum powder to stop wooden floors from squeaking.