Black mould, damp walls and condensation

[Kattinger]

I need a solution. One that really works. I have black mould caused by condensation in my kitchen mainly. This is a large, as in has study, sitting room and dining room and two bedroom 1950's bungalow (upgraded with DG , CH and such although kitchen does not have a heat source in it) in the SW of England.

No mains gas. Coal and electric only.

In winter the back wall ( N and NE facing) is constantly damp. Sometimes when I am washing/cooking in there you can positively see the water trickle down the back wall. Its black with mould and its growing and spreading out. Now our health is being affected - chest infections, sneezing, itchy eyes. In summer it gets better but the wall never completely dries out. Its a cold room.Temp in theretoday is 9degrees C. Yesterday it was 5 or 6 degrees ( and colder at night)

I know they say you should minimise your use of water and such activities, but come on, its a kitchen and I am almost down to doing little other than breathing.

I have tried
a) opening windows- just makes things colder.

b) removing a pantry - just means mould is now on back wall and in corner where pantry was rather than having a soaking pantry.

c) not cooking, washing or using dishwasher above twice a week ( means I cannot clean up properly, especially this time of year when I need to dryclothes in tumble dryer -condensing type, down the drain to outdoors.

d) a dehumidifier. Has worked to an extent. Problem is eased but hasnt cured it.

So, what really works?

I am looking at

a) putting a heater in there - would this work or will it just be another cost like the dehumidifier?

b) building a conservatory/ car port on the outside wall which is damp
(my neighbour did this, but I do not know how effective it was).

c) one of those systems I keep hearing about on the radio (advert) which says it cures mould from 500. Dont know what this is- but likely not cheap. Some sort of ventilation system in the roof?

Any help would be welcome ( short of moving house, we cannot).

Not a heater, try an extractor fan and air bricks?

you neat heating and ventiation.

opinions on ventilation differ but I think airing the whole house a couple of times a day works well.
open all windows as wide as they go mornings and evenings for 10 min. this means the warm damp air from inside is replaced with colder, drier air from outside without cooling down the walls. the drier air also heats up quickly so there is no need to sit in the cold.

It sounds as though moisture is condensing on that wall because it is cold. Is it a cavity wall? It sounds to me like it needs insulating so that the wall stops being cold and possibly improved ventilation as well so that the moisture has somewhere to go.

a) have air bricks.

b) heating in house would be lost with opening windows. Already open windows a little permanently and its cold and damp and we just end up shivering. We do not have a instant heat source here. No mains gas. Coal fires and electric heating are not the same ( even when running a CH system).

The outside is cold and damp. Its wet this morning. Yesterday was frosty and wet all day. This is Cornwall. It rains a lot and is always damp. ( I have heard this issue of condensation and mould often referred to as "The Cornish Problem").

Loks like it might have to be the 1000k jobby then does it? Ventilation through the ceilings/ roof - will it work?

I'm not surprised you're cheesed off, that sounds hideous to me.
I agree that the room needs to be ventilated and heated, 9 degrees is far too low, and 5 or 6? That's not comfortable surely?
What sort of walls do you have? If it's a 1950s house, I'd expect it to have cavity walls, in which case, it should be warmer than that.
If it has solid walls, have you thought about insulation? You can insulate the interior or the exterior. I think the room is too cold and insulating the walls would go a long way to resolving the issue.

If you don't have an extractor fan in the kitchen that is the first thing I would put in

I honestly don't think ventilation alone will be enough.

I also think you need to insulate that wall as it sounds like the wall is cold and so all the moisture is condensing on it. And then install an extractor fan, again on that wall, so that any moist air it does attract is then dispersed outside.

I live in a really old damp house and that's what worked for us with our Wall Of Doom!

opening the window for ventilation work as long as it's colder outside than in, even when it rains.

simple physics: warm air can hold a lot of moisture, cold air can't keep hold of is, which is why you get condensation on cold surfaces.
so by heating the rooms in winter is important.

piglet john can explain this so much better

you also have to consider that a gas fire generates quite a bit water vapor.

I have ventilation via extractor fans and windows.

We do not have gas at all.

However, we found closing the extractor fan and vent on this wall seems to have made things better. The wiondow/ vent which once served the pantry was causing lots of condensation. Its a window with a glass back and at the front is a wire panel and it opened just a bit at the top to allow air in, if anyone understands that. It was a ventilator for the old pantry. that was in this wall In fact DH put a thick polystyrene foam block in the window/ vent and that has made things far better. So we decided that it warmth we needed.

New insulation in ceiling seems to have made things worse though. We didnt get wall insultation because we were worried about the efect of condensation in this room.

We got a dehumidifier and that has helped but will not seem to cure it.
I like the phrase " wall of doom" adventcalanderforcats. It describes it well.

It is a cold room I accept that. Far colder than anywhere else in the house. Yes, I might say we do seem now to be colder in this room than outside sometimes. But I didnt want to justify heating it when I am not in there- although being cold it sucks the heat right through from the other rooms if we open a door.

All advice and ideas really being welcomed here.

Have you got a water meter?

Is the floor concrete?

Is the room original build or an extension? Is there a room above or a roof? Flat?

How big is the extractor fan and when do you use it?

Is this a 13" cavity wall?

Look outside for sources of damp such as spilling gutters, leaking downpipes, cracked render, bad pointing.

Have you got a water meter?

No, we do not have a water meter. The bungalow was built in 1958
(cavity wall) . Its rural if that helps.

Is the floor concrete?

Floor is suspended wood with a four foot void beneath. We had some mice get in through the air vents in the wall below floor level, and DH had floor boards up to get at them. The base is concrete on pillars and suspended floors and it is quite dry down there according to hubby. The cavity is also dry - we had a camera down when we werelooking at having insulation in it. Only damp is on the inside of this wall.

Is the room original build or an extension? Is there a room above or a roof? Flat?

Its original under a normal roof. The roof is insulated to a high level. This we did get done last spring. The loft insulation is now above the rafters level.

How big is the extractor fan and when do you use it?

I am not sure I understand this question. Its an expelair in the wall. Switched by an electric switch. It can be opened manyually and left open but we found that makes it worse.

Is this a 13" cavity wall?

Standard build cavity wall? If 13ins is standard, then yes.

Look outside for sources of damp such as spilling gutters, leaking downpipes, cracked render, bad pointing.

I have asked DH to look at these. The pointing is all good. Render is all good. Guttering is cleaned out. He repaired a downpipe and now nothing seems to leak but we plan on changing it all next year together with facia sofit and gutterings.

We had new DG windows last year too and a new back door ( the other one used to drip with condensation and was rotten. The new one is plastic and does not get condensation. Only the wall.

I am guessing it is just us causing the trouble then?

I spent yesterday afternoon drying the wall off with towels. Its far better this morning but the tempreture this morning has risen too and its dryer. The room is now around 10 degrees internally this morning. It does seem to get worse if its cold out or if its raining.

Every surveyer who has been in always tells us the bungalow is well built to high specifications and in good repair if that is any help. It was originally it seems archiatect desigined and built by one of the best builders in the area it seems. But that was a long time ago.

That seems like way too much water! Are there any similar properties either side of you that have a similar problem? Perhaps a problem with construction or type of materials used?

Either that or is there ANY other source of water? An old immersion heater, loft tank or any old pipes still holding water that could have cracked in the cold weather?

Has the property been empty/freezing for a long period of time?

From what you say, there does not seem to be water coming up through the floor. Presumably the subfloor void is well ventilated with unblocked airbricks on all sides. There appears to be more water vapour in the room than can escape through ventilation. Either the ventilation is very bad, or there is excessive water being released into the room. You don't hang wet washing or towels inside?

There might also be plumbing leak from a pipe buried in a wall, or around the sink.

Tape a piece of clear plastic tightly to the damp wall. Observe if water forms on the wall side if the plastic (wet wall) or on the room side of the plastic (condensation). Do this in several places.

This is a room with cavity walls (albeit uninsulated) and an insulated roof. It would benefit from being kept warmer. Even a 600W oil-filled radiator would help. I would aim at 15C for a start, and if thermostatically controlled, will not be very costly because it will turn itself off as the room reaches temperature. If you have an electric dehumidifier, that will also heat the room. If the room is the coldest part if the house, then warm moist air diffusing and circulating around the house will cause condensation there.

Do you get condensation on the windows? If so, run the extractor fan until it is gone, and often enough to prevent it recurring.

Insulation and ventilation used together do not cause condensation and damp, they reduce it.

I have done the sticky tape test. It is condensation.

The windows do get condensation on them. I have bought a Karcher window vac for this. The new windows do not get as much condensation as the old ones did.

I have also gone out and purchased a convector heater for the room to tryand raise the tempreture.

It sounds to me as though that wall, particularly being on the north, is just too cold.

We live in a 1960's bungalow, and it too is prone to mould and damp. Ours is worst in the former garage (now a bedroom), and around the windows, where we think the nature of the construction (and massive solid concrete lintels - cold bridging) are causing the problem. The ceiling in the en suite also used to be black, until DP installed a heated towel rail (heat source) and an extractor fan (ventilation). He's since treated it and replastered it and it hasn't come back in a year.

So increasing warmth and ventilation are I think key.

If moisture is condensing so readily on the wall, and with your kitchen being 5-9 degrees C at the moment, that wall must be freezing. You need to warm up the wall itself, with insulation; being north-facing, it's never going to get a ray of sun on it to help warm it from the outside, so all the warming needs to come from you. Go for either cavity infill or external insulation (you can clad or render over the top) - internal insulation can be problematic and make condensation problems worse.

Our coldest rooms - the bedrooms at the opposite end of the bungalow from the wood-burner - are the most prone to mould. So warm the room up if you can. I agree with a previous poster who said have an oil-filled radiator on low, on a thermostat, all the time, keeping the room ticking over above 15 degrees (18 would be better). You could try it for a week, just to see if it makes a difference and monitor how much energy it uses? Also, we had a wood-burner fitted in our bungalow three years ago (ours would get down to maybe 10 degrees inside, with the heating on) and it has made a massive difference, removing the cold/damp feel of the house (as long as it's lit!). Is there anywhere suitable you could install a wood-burner (assuming you can budget for or get free logs)? Somewhere in the heart of the house would be good. Get the warmth levels up! Easier, and cheaper, would be getting a plumber out to fit a radiator in the kitchen off the existing central heating circuit, and possibly locate it (or one of several) on the cold wall.

Your ventilation seems pretty good - I think warmth is key here. Any room that's regularly as cold as your kitchen is going to feel damp and mouldy (some kids had left hoodies in the changing rooms at DS's football club recently, and I noticed they'd gone mouldy!).

One other thought just to cover all bases, although it does sound like a cold wall and condensation problem, is to check that your damp-proof course hasn't been breached. This is the line you can see in the brickwork around about floor level, on the outside of the property. Nothing should go above this that could introduce moisture into the structure - soil (flower beds), stacked wood, etc.

Bit of an essay there! Good luck with getting it sorted.

The problem is that that wall is the coldest in the house. People living in a it house produce damp simply by breathing. If the house is all warm enough, then the air can hold a lot of moisture, and then a bit of airing/extractor fan and the moisture is removed.

If the house is very cold, then the air in the house can only hold a tiny amount of moisture, and then it condenses out onto the coldest spot, where-ever that is, and in your case it is the kitchen.

So, assuming you have extractor fans in kitchen and bathroom that actually work, and that bathroom door is kept shut after showers. Assuming that you don't add lots of extra water through drying lots of washing etc, then basically you need daily ventilation, which you have, and warmth.

So I would agree with pp about oil radiator.

We had constant mould and damp in our living room for same reason (coldest room in the house) and the carpet rotted away under the window.

We have internally insulated the outside wall, which is old and not cavity wall. We have also installed a wood burner in that room. The wood burner is fab, really worth it in terms of warmth and taking away damp feel etc. But we only put it on at the weekend, and during the week the room is now damp and mould free due to the insulation.

We have similar problem, and we are in .cornwall - especially cursed in this damp county as we live in the valley between 2 rivers...

Couple things that helped us:
Oil rad on low all the time and dehumidifier in kitchen, also our coldest room, when boiling big pots and kettles
House thermostat set so stays constantly warmish rather than dipping to freezing and warming up in Eve's etc (DH hates this, but it works for us as back of house has zero heat source)
Nothing dried indoors
Our damp course had been breached with previous owner hammering nails into it, this has been redone and made a small difference
We had a missing piece of render behind the down pipe just below gutter. Heavy rain at a particular wind direction and water streamed in. Took several years (and builders) to identify but fixing has made a huge difference.
We wipe walls, windows daily with cloths (tedious- is the Karcher vac worth it? I think it is on my wish list) and I use the LG mould cleaner on days I can ventilate the house.
We were advised to keep bathroom door shut as problem was made worse by steam travelling to coldest point of house, and I never have doors and windows open on damp misty days, not even to ventilate.
And I excavate cupboards to clean at least twice a year - a very cornish problem that kitchen cupboard condensation
It's all a pain I know -- but we have had 2 cracking summers with many beach days!

We have this too - the north wall of our very old house. Only in our bedroom though and not the other rooms so obv condensation. The woods start about 20 feet away so as well as being north facing it is made 'darker' by the trees. The walls are about 2 ft thick, brick and flint.

All structurally sound. We solved it by actually putting the heating on in there, I usually have the TRV on the frost setting but now have it on 4, which is a bit warm for me but not for the tiny spots of black mould that were appearing.

I always crack open a window for a few hours a day whatever the temperature too but warming up the room seems to have done the trick.