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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> White Powder - Mold? - In Basement https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1364473698 Message started by Ant on Mar 28^th, 2013, 12:28pm

Title: White Powder - Mold? - In Basement
Post by Ant on Mar 28^th, 2013, 12:28pm

This is the archway linking the two halves of my basement - I believe it is in a load bearing wall.

I have a dehumidifier in the basement which has cured all previous smells of damp, and there are two radiators providing heat down there.

The powder is dry to touch, and when you wipe this powder away it returns within a couple of weeks and gets thicker the longer you leave it!

The basement was damp proofed by the previous owner, but I think it was a pretty cheap job - just a layer of polythene sheet behind the plaster board.

What is the white powder?

How do you get rid of it?

Thanks in advance for any advice!

Title: Re: White Powder - Mold? - In Basement
Post by TIMBA-WOLF on Mar 28^th, 2013, 4:21pm

Is that plaster beneath the "Mould" as you call it....

is the area above totally dry now, or is moisture still getting in...

and that "mould" actually looks to me like effervesence (salts and minerals coming through!!)

Title: Re: White Powder - Mold? - In Basement
Post by Natedog on Mar 28^th, 2013, 4:25pm

TIMBA-WOLF wrote on Mar 28^th, 2013, 4:21pm:

that "mould" actually looks to me like effervesence (salts and minerals coming through!!)

2nded. looks exactly like what was on our bathroom wall when the roof was leaking

Title: Re: White Powder - Mold? - In Basement
Post by Ant on Mar 30^th, 2013, 11:16am

Thanks for the replies - it does seem dry now but must be cracking and getting through the plaster?...

Whats the remedy?

Knock it all back? See if I can find the source of the moisture? Then is there any waterproofing to add before re-plastering?

Thanks again....

Title: Re: White Powder - Mold? - In Basement
Post by Natedog on Apr 7^th, 2013, 8:09pm

you'll need to find where the water is coming from before you can work out how to stop it. i'd start with a thorough check directly above it for any leaking pipes. a cheapy damp meter (search ebay for 120645124866 ) tha i use for checking firewood before burning it helped me trace the damp in out bathroom. even though we were only getting a fluffy wall in one small area, i could trace the damp patch (you couldn't see it or feel it by hand) up the wall, then up the sloping ceiling. only down side its that it does leave 2 little holes in the surface

Title: Re: White Powder - Mold? - In Basement
Post by londonman on Apr 10^th, 2013, 1:26pm

TIMBA-WOLF wrote on Mar 28^th, 2013, 4:21pm:

.....
and that "mould" actually looks to me like effervesence (salts and minerals coming through!!)

Of even efflorescence ;D You're thinking about all that Alka-Seltzer!