Mould prevention

[Matt42]

Hi,

On the interior of a couple of our walls, mould keeps forming. The walls are the more exposed ones i.e. No trees or buildings near. The mold keeps appearing down by the wall near the skirting in the autumn and winter and I have to keep spraying mould remover on the walls evry few weeks every time I smell some damp in the air. I think its just condensation causing the mold, the walls are just old breezeblock types layered with plaster and wallpaper so have no cavity insulation etc. I think damp appears because the walls never heat up (always cold to touch) nd hence are a different temperature to the inside air temperature.

I need a more permanent solution other than possibly a dehumidifer permanently on, can anyone suggest anything? Its impossible to keep the window open for long periods as there's no fan light window. I am beginning to think our new mattress smells slightly musty in one corner now also and it's only 8 months old.

Thanks

Matt

 

[Burnerman]

As with all issues such as this, ventilation is the key.....the room moisture content has to be reduced.
It sounds like the problem wall faces north and always remains cold?
Ensure that the bathroom and kitchen are vented to the outside, don't dry washing in that room and keep any furniture away from that wall if you can.
A dehumidifier may well pay dividends - if the interior temperature is cosy, even a domestic machine can remove 5 litres of moisture a day.
John

 

[foxhole]

There are mold spoores in the air constantly, you need to prevent them settling and prevent the damp conditions they like.
Permanent ventilation is only option, heating will increase the amount of moisture the air can hold so only aids the removal of moisture.
Ideally every occupied room needs a vent and bathroom and kitchen need mechanical vents [extractor fans].Drying clothes indoors should be avoided as this is a cause of damp.

 

[Matt42]

The wall is south facing but it might as well face north, it gets buffeted by the wind and rain compared to the north side and yes its always cold, freezing in winter and cool in summer. The upstairs is the standard 3 bedroom, bathroom, landing type so no washing etc. The bedroom is always the coldest in the house, not sure if that contributes. Furniture away from the wall is more a dream than a reality unfortunately with big family small house!

A dehumidifer might help but you can't have it on 24/7 throughout winter, the noise and electric bill would be hideous.

 

[Burnerman]

Assuming the building exterior is in good condition then air exchange is the solution....a dehumidifier consumes around 200W on average and they are a little noisy to sleep through!
You could consider lining the wall with insulation slabs and then covering them, but you'll lose some space.
John

 

[JohnD]

does anybody drape wet washing around your home?

 

[Matt42]

Yes, clothes airer during the winter as we dont have a tumble dryer but thats downstairs and the other end of the house.

Can I redecorate but using mould resistant paint and wallpaper? Is there such things? I noticed ages ago when I moved in the house that the back of the bedside drawer cabinets also near that wall were coverd in mould on the back, the cheap hardboard type so I had to replace the back of the drawers whereas the back of the bed which is a smooth wooden frame, the mould had not touched. What's the science behind that?

 

[JohnD]

//www.diynot.com/wiki/building:condensation_in_houses

 

[Matt42]

So reading the web link. The condensation appears in my house on the colder walls. So they get colder in the autumn/winter and hence a layer of condensation occurs on the inside where the cold brick meets warm inside air? Same theory as to why condensation occurs on our windows? So I can experiment by sticking a polytheme surface onto and then mould can attach? Goes back to my earlier point about whether paint/wallpaper can replicate that?

 

[JohnD]

if you are able to get cavity wall insulation (it is surprisingly inexpensive, and your gas or electricity supplier may offer a subsidised or even free installation) the inside walls will be warmer, so less prone to condensation.

Improved ventilation will reduce the moisture burden in the air.

Examine your gutters, downpipes and roof for any leaks or overspill.

 

[Matt42]

As before, my walls are solid concrete breeze blocks type. You can't put cavity wall insulation in them. Even channeling in a light switch is a major 'chiselling' and plastering exercise! No Leaks or overspills, the outside of the house is in good condition.

Looking up mould resistant paint. How about I redecorate back to plaster, mould resistant lining paper and then mould resistant paint? Not sure that would prevent inside condensation occurring though, although if mould spores won't cling to it then I'm not bothered about a bit of inside condensation.

 

[foxhole]

Waste of time, mold will grow elsewhere , ventilation and not drying clothes indoor is only solution.

 

[Burnerman]

Matt, are you certain you don't have cavity walls?
Single leaf breeze block construction is definitely non standard, and most properties like this would have a pebbledash finish on the outside.
John

 

[Matt42]

I have a pebbledash finish on the outside.... My house was built in 1912. Why would single leaf have pebbledash exterior?

 

[Burnerman]

Obviously, properties with single leaf construction needed all the help they could get to remain watertight, and one simple way was to pebbledash the exterior and then paint it.
Obviously any failure in the rendering would allow water to penetrate and give rise to problems within.....it didn't help with the insulation factor of the wall as no one cared.
People in those times didn't worry about it - they just lit bigger fires!
From your description, it does sound like the problems just stem from the wall being very cold.
I do sway towards the use of a dehumidifier.
John