Black Mould

[greencard1]

As soon as the colder weather comes, I get condensation followed by black mould in parts of my house (cavity wall house, with retro fitted insulation, and solid floors).

I try to keep the condensation to a minimum. I have got a window vac, and have painted zinsser anti mould paint in mould-prone areas. I have even stuck polystyrene tiles to one wall to warm the surface up. As soon as the warmer weather comes again in summer, the mould can be reduced by sprays..

At the moment I have mould on the bathroom ceiling that seems to be UNDER the zinsser paint; and mould in the tile grout. The usual cillit bang etc bleach sprays do not get rid of it.

Any tips greatly appreciated.

Thanks
John

[cookiesdaughtersdad]

Without seeing some pictures and allowing that the gutters etc are fine, its all about excess moisture and air movement.
Bathrooms are always a trouble and should have a suitable extractor that can change the air at least 10 times per hour, that where i would start with the bathroom.
As A bricklayer I always though that retro fitted cavity wall insulation was kind of a mistake but just think on the idea of how each room is being used, what air flow there is and the humidity. Dehumidifiers are quite cheap nowadays and well worth trying but you must calculate the rooms volume before purchase as you must with extractors.
Cookiesdaughter works for the local housing association and knows that it is often how the occupant uses the property that is the problem.

Cheers, Alan

[greencard1]

Thanks Alan.

How do I deal with the mould that seems to be under the paint...possibly even in the plaster?

Do I have to strip it all back somehow?

[cookiesdaughtersdad]

Thanks Alan.

How do I deal with the mould that seems to be under the paint...possibly even in the plaster?

Do I have to strip it all back somehow?

Any thing you feel is holding moisture in or needs replacing consider removing but get some air flowing over it asap such as with an office fan. Try contacting a local decorator/bathroom fitter/builder for advice and possibly an estimate for doing the work.

Cheers, Alan

[greencard1]

Thanks again.
The mould in the grout makes the bathroom look terrible.
In the summer I thought I would try to remove some of the darkened bits and put some new stuff in.
I bought a diamond tipped blade for the multi tool, and.......it never even scratched it!

[Mike J]

Thanks Alan.

How do I deal with the mould that seems to be under the paint...possibly even in the plaster?

Do I have to strip it all back somehow?

Moist air condenses on cold surfaces and if the mould isnt widespread the problem could be the same as a freind experienced? He had the ripped up rag insulation installed in one wall and monitored the wall temps before and after and he said it made the wall colder, also that it had sunk down the cavity in less than a year.
A few drill holes would soon determine if the same has happened to yours?

Seems if its damp under the paint the damp is coming through the wall and the insulation has sealed off the movement of air. Ive cut holes in cavity walls and just by putting you have inside you can feel the inner walls are wet, not damp, wet.

Me, Id remove a brick and remove all the insulation from the problem area.

.

[DaveGreenwood]

Sodium Hypochlorite (strong bleach its about 14%) watered down or neat for bad areas will get rid of tile grout mould, used in a spray bottle.

https://www.amazon.co.uk/JOVS-Sodium-Hy ... 5c0b49b9c5

[greencard1]

Thanks Mike and Dave.

I got a bloke in from the cavity wall insulation institution, under the 25 year guarantee, which was about to run out.
He drilled a hole in the mortar in the problem area and put a camera in. The insulation was still in place, had not sunk, and there was no damp. Good suggestion though Mike.

I am going to get some of that bleach and kill the b@stard stuff.

Thanks again both.

[fergie68]

My house never suffered from damp until I got cavity wall insulation. I only got it because a elderly neighbour was getting it free ( I had to pay) she's long gone now I'm looking at getting it sucked back out.
As a roofer I see regularly the damage over insulated attics cause. They need ventilation and lots of it.

[ChrisWales]

Add or create air bricks for ventilation, you can get a fan that forces air through your property (not an extractor fan), makes sure the kitchen and bathroom are well ventilated, trickle vents on windows, dont dry clothes on radiators etc.Dehumidifier would help.
All assuming its not damp rising/penetrating in.

[greencard1]

Thanks folks.

Yes it is just condensation; not rising damp or anything like that.

I did increase ventilation in my roof space a while ago because during cold weather, water droplets were dripping from the felt down on to the lighting wiring.

Thanks again.
John

[Danoutdoors]

De humidifier could help, reduces the amount of moisture present in the rooms, just costs a few quid to run is all.

[ChrisWales]

https://www.permagard.co.uk/ventilation ... entilation

[Steve Le maitre]

Sticking the tumble dryer out in the shed was the best decision, all that moisture would have been wreaking havoc

[greencard1]

Thanks folks.

I had never heard of PPV before. Interesting stuff.

[andrew_nagel]

All the rooms in my house except the living room have passive air vents. I never close them - just adjust them between winter and summer. The bathrooms and kitchen have humidity controlled extractors + passive vents. All the windows can open on a crack while still locking and covered by insurance. Drying washing indoors, big potted plants, fish tanks all create lots of condensation. Sounds basic but opening the windows on a crack for a couple of hours a day does wonders.

[Mike J]

Thanks folks.

I had never heard of PPV before. Interesting stuff.

Also available are two way solar powered fans that open and close according to temperature.
Very useful for a room like a basement or one with no windows.


I had mould problems and killed it by brushing on lemon juice following the advice of a neighbour.
(But I was living where lemons were so plentiful nobody bothered to harvest them so all it cost me was my time).


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