Where to start with damp and mould

[Littleredwagon2308]

We've got mould growing on many of our walls of our owned property. How do I go about finding out what the cause is? It's quite widespread. Could it only be because of lack of heating and ventilation? We open all the windows once a day for minimum 10 minutes and usually for 30 minutes (often longer). We didn't switch the heating on until the temperature was below 20C. Should have we have switched it on earlier? At night it's set to come on if the temperature drops below 16C.
Who do we call for advice? Do we call a builder? A structural engineer? Who?

Also, the mould is also behind the kitchen cupboards. What do we next there? Remove the fitted kitchen? Paint walls with special paint? Install insulation board? Install a heater under the cupboards? Drill ventilation holes?

I just don't know where to start! 🙃

Well start with a couple of big dehumidifiers and then wait until someone more clued up than me shows up here!

Is the problem downstairs or upstairs or both?
How's the roof?
Do any of the window frames let in water round the edges?
Do you have any leaking downpipes or a broken gutter, so water runs down the outside wall?
How old is the house, and does it have a damp course? Is the damp course visible or is it covered by paving or soil?
Are there any air bricks and are they blocked?
Do you have cavity wall insulation?
Is the property rendered?
How long have you lived there, and did you get a full survey done when you moved in?

Forgot one - could you have leaking pipework anywhere, such central heating pipes under the floor?

OK,

Is it a house or a flat?

Do you do everything you can to limit lifestyle condensation - do you run a dehumdifier if you dry clothes indoors, do you have kitchen and bathroom extractor fans, what is the construction of the property (single skin?).

Have you check the external guttering and down pipes?

Is the mould only happening on external walls or is is affecting internal walls as well?

I think 10 - 30 mins for opening windows is not enough We have a single skin solid wall flat which can be prone to lifestyle condensation and we keep the bathoom top window pretty much pernamently open and the same with the top window in our main bedroom. All other windows are open for at least two hours in the morning regardless of the weather.

Buy https://www.amazon.co.uk/Damp-House-Causes-Treatment-Dampness/dp/1861269668 book. It's really comprehensive, but easy to understand and explains all the potential causes and relevant cures.

Absolutely brilliant book.

Yes! I'll be buying a dehumidifier.

First think you need to do is figure out what is causing the problem. Needs lots more information before this can be determined

Do you have internal and external photos you can post? How long have you lived there? Is it on every wall? Just external walls? Just some walls? Has there been any new insulation added? Any recent works like rendering or pointing? What condition is the roof in? Are the gutters running freely with no leaks? How are the windows and doors?

As already mentioned already, there are many reasons for damp and mould speads very quickly, so it is important to deal with both and not cover it up, as it will come back if not properly dealt with. Get a device to check the humidity in your home, to check walls, areas of the homes for humidity /cold spots. Are your windows opened at night or trickle vents open, as you can produce a great deal of moisture in a home just by being there, let alone washing, leaving wet items in sinks, condensation, leaks etc., and homes should be heated to avoid issues, never falling below 14c is recommended. Check out the below and remember that mould is also bad for health, as are some of the washes to clean them, so please do wear gloves, well ventilate and wear masks when applying the specialised washes to deal with the mould areas.

The problem is upstairs and downstairs, behind furniture which up up against the external north east and north west walls. Some has been found on other external walls (SW), but again only behind a piece of furniture.

The roof should be OK. We had some work down to it 10 years ago.

There is a leak down our chimney when it rains heavily and high winds (so a few times a year when the conditions are right). This is since when our stove has been fitted. Someone has been up there, but couldn't see where it originated. Should we go up in the loft?

Double glazing was put in 10 years ago. One window in the lounge lets some water in when it rains a lot, but that's not where the mould is. One large window and a French doors are still original single glazing.

Down pipes and gutters all OK.

House was build in 1979 I think.

I'll have to look up what a damp course looks like.

Only 2 air bricks on SE wall and those are free.

We don't have cavity wall insulation.

The property is rendered.

We've lived here 5 years.

No survey was done as it is an inherited property.

All fabulous Qs!

So you have at least two known points of water ingress. This could be contributing to the walls getting soaked and attracting mould.

If you have a friend with some building knowledge, ask them to take a look. Water can enter / come down a cavity between the internal and external walls and it is definitely worth going into the loft to check, especially if the area is common from the top down on the building. Happens more often that you would believe.

Before you can tackle the damp on the inside, you need to make the property watertight from the outside. So I reckon you need to get someone up on that chimney again. Get the window in the lounge re-sealed again as well.

There should be a damp course in a property that age - it is usually low down on the walls, maybe one or two bricks above ground-level and there should be a difference in appearance of the grout in a horizontal line all the way round the house. It is usually in the row below the doorstep. If you can't see anything, then that is a problem and you will need to get a surveyor to come in and assess it. If the house was rendered after construction, then they may have covered up the damp course and that will be a big issue.

Definitely start with the chimney. I'd take an educated guess that there is an issue with the flashing or the pointing. Get a decent roofer up there.

Do you have trickle vents in your windows and are they open? If not make sure they are.

What construction is your property?

Obviously finding and tackling the cause is paramount.

But for cleaning off the mould in the meantime to improve the air quality, the best thing I've found is HG Mould Remover Spray (it says it's for bathrooms, but I've used it on walls etc too).

https://www.amazon.co.uk/Bathroom-Mould-Removal-Spray-500/dp/B00IN3BLQS/ref=sr_1_6?crid=3O0GREKQBMOIA&keywords=hg+mould+spray&qid=1700502935&sprefix=hg+mould+spray%2Caps%2C96&sr=8-6

Even if the window and chimney leak is rare and no where near the areas of mould? Obviously during those times it's contributing to the overall water content of the house. but so are baths. Do you mean the problem could be worse for the chimney but I don't know it?

My double glazing don't have trickle vents.

What do you mean by "construction" please?

Lack of ventilation / lack of heat is 99.99% of your problem.

Get trickle vents installed and turn on the heat for a few weeks.

It sounds like rising damp? I would get someone in to have a look at it. We had it in this house and caught it early so didn't cost as much as I thought it would of done.

What do you mean by "construction" please?

In short posters need to know more about your property to help you so answer questions like -

Are your property walls made of bricks, concrete or another material?

Is your roof tiles, slates, thatch or another material?

Do you have a flat roof?

Oh and if you furniture is right next to your outside walls move it all forward a few inches so air circulate behind it.

I had mould on part of one of my walls when I moved into my property. That part of the wall was behind a fixed cupboard. I removed the cupboard, cleaned the wall, decorated it and ensure any furniture I place has a few inches gap. The damp which was actually condensation has never come back.

@Littleredwagon2308 I mean it's not be the sole cause of the damp and mould but it's not going to be helping.

I've taken some of pictures of where I think my damp proof course is, that ridged line?
One picture of part of my external wall showing that the rendering seems to go down to the ground, which I don't think it should.
What do you think?
I don't think the damp proof course should have been rendered.
I don't think the rendering should have been applied all the way to the ground.
Perhaps over the decades the earth has been allowed to "grow" up the rendering and should have been periodically removed?

Can you have them retrofitted onto exciting windows?

The walls are made of these large blocks that look a bit like breeze block but are really heavy and a darker grey. They are really tough to screw into.

The house was rendered (see picture in above post).

It's a chalet bungalow - There is an upstairs but it's got slanted ceilings and cupboards in the eaves.

The slopping roof is tiled and the dorma bathroom was redone about 10 years ago with a slopping roof.

I am always hearing about people turning their heating on and off to save money. Well if you want to be continually redecoration that is the way to do it, as you will get mold on walls

I was responsible for some stored aircraft on an M.o.D unit. Reading all of the publications, I realised if the temperature varies by about 4 degrees the Dew point is reached. I put a thermometer and a hygrometer in the building and kept the temperature within these parameters. I had mold forming in my own house in corners, so I regulated the temperature controls to be on 24 hours day at 70 degrees F: result no more mold, no more expensive decorating.

The £300 you may save on bills cycling the heating will just disappear in decorating bills. This won't apply if you have a space-age house with a flat roof, special plant Life on the flat-roof and insulation 10 feet thick. I am talking about normal people who spend their life hanging on to the gas and electricity meters in terror, waiting for the next bill to arrive: not a space age environmentalist. Just do what I do and save the £4000 a year to pay the heating bills and be warm and forget all of of the complicated heating controls. If you go away for a few weeks set the thermostat to 56 deg F. Yes 56 deg F, I live in he British non EU Stone-age and am happy.