Mould Problems

22 Dec 2007
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United Kingdom

I wonder if anyone can help me with this one...

About 12 months ago, having had enough of black mould appearing on a cold internal wall which attracted condensation, I stripped the wallpaper (which was thin paper), painted the bare plaster it with anti-condensation paint, then papered over with thick vinyl wallpaper. I also had cavity wall insulation fitted throughout the house to retain heat generally.

Occasionally on very cold days the wall does feel damp to the touch through condensation settling, however the black mould does not grow anymore on the paper :) I also increased heating and ventilation around this time to help control it by introducing trickle vents and an additional electric heater.

Today though, my wife noticed that several parts of the white vinyl wallpaper have started to turn an off white/yellow colour about 12" above the skirting board. There is still no evidence of black mould, but I noticed within the yellow spots there appear to be small nodules which are pushing the paper up (looks a bit like acne). I sliced one of these open and tore the paper a little and this revealed a very fluffy, cotton-wool like white mould growing sporadically behind the paper.

Can anyone help me with this? Why after redecorating has the black mould gone but introduced white mould? And what's best to address this (I presume the wallpaper will require stripping again to cure it)?

Any help greatly appreciated!


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cold internal wall
Did you mean external? ;)

Afraid it seems to me you got a damp/ leak problem here. Anticondensation paint will only protect the paint film of the anti/con paint, so if you paint/paper ontop of this it will be awaste of time.
Did you bleach / apply anti mould solution to the area before paint?as it's growing under the paper I reckon you need to check for problems on dampcourse or, Is there a rain/wastepipe leaky guttering on wall outside the leak?
good luck
No the wall is internal - its a north facing cavity wall, fitted with cavity wall insulation, and is cold to the touch most days.

I treated the wall with bleach twice prior to decorating last year.

There's no leaky gutter. If it were a damp-proof course issue should the bottom section of the internal wall immediately above the gutter not be damp (this is about 12-18" above the skirting)?

I was thinking of taking a brick out of the external wall, moving the insulation to one side, and seeing if anything is amiss on the internal wall (e.g. a bridged wall tie).

I didn't see any evidence of the bare plaster being wet or damp when I decorated last year.


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Hi jamie.

I have similar problems although i dont have the white fluffy mould problem as yet. Im certainly no expert but i wonder if its something to do with the wallpaper you have used and the anti-condensation paint not reacting well together therefore it is being unable to breathe which causes the white mould.

Have you thought about dry-lining the wall?? Might reduce the risk of condensation, if there still is any?

Try a specialist paint called Silexine anti-mould paint. Expensive but very good.


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