Why do houses in the uk mould so easily?

[december2020]

My understanding is the main causes for mould is condensation, humidity and rising damp.

I live on the UK but I'm originally from Scandinavia and mould doesn't seem to be a problem like it is in the UK, yet there is humidity from steamy showers and cooking in the kitchen as well as prime condensation conditions like warm inside and cold/minus temperatures outside - but the windows never have condensation and it's rarely a problem.

Why is this? Maybe a dumb question on my part! Im really curious (also in case there is anything I could be doing to future proof getting any mould).

My house is quite old and I think it ‘works’ differently to a modern house. We have original tiles in the hallway and moisture comes up through them, there’s no damp proofing there. We need to make sure there’s ventilation for the moisture to get out. When we first moved in the fireplace downstairs had been completely bricked up with no ventilation and there was a real condensation mould problem, much better now we’ve opened it up again. So it could be to do with construction method?

I find it also helps if I open windows upstairs at some point in the day. Trickle vents or the option to lock windows when cracked open a tiny bit can help prevent mould, plus air bricks and vents.

The UK has the oldest housing stock in Europe - this presents two problems, firstly a lot of houses weren't built with damp proof measures we expect today. Secondly, a lot of added in damp proof courses serve to block the breathability of houses, exacerbating the problem. Lastly, although this will vary, the UK is largely a pretty humid country.

In terms of future proofing, the best thing you can do is be careful what property you buy!

There are lots of old houses that have no cavity between the bricks, and no damp proof course, so that doesn’t help. I’m not sure how old the houses are in Scandinavia ?

Scandinavian housing stock is generally newer than British and designed for modern living. People in Victorian houses weren’t showering and washing and drying clothes as much. Plus older housing needs maintenance which some landlords don’t do. People living in older housing stock have to open windows and improve airflow, etc. or use dehumidifiers. But they often don’t understand this.

Google ‘old houses need to breathe’ and you’ll find explanations and tips. It helped me to understand how to treat the problem and allowing this ‘breatheability’ works better than attempting to retrospectively damp proof.

I'm in a new build and have problems around the windows. We ventilate etc, but have dark mould in the corners of one bedroom window.

I don't know whether we don't have enough heating on or what. Frustrating.

A fellow Scandinavian here who used to live in the UK. I think the main issues are the lack of ventilation, poorly contructed houses, flimsy windows, lack of efficient heating. Also, the UK has a higher level of humidity than the European continent so the outside air just makes it worse.

Lack of ventilation is the reason, if there isn't an obvious blockage or leak. Rising damp is when there is blockage channelling moisture into the walls if it cannot go elsewhere. Even ancient houses can be damp free or well managed if properly ventilated.

Not Scandinavian but German. I think it's down to a few things. Generally much poorer building standards (often because the houses are simply very old). And not heating and airing out properly. We moved into a house a year ago that was riddled with mould. Cleaned it, started a strict regime of regular airing out. No more mould.

Even before COL crisis fuel has long been more expensive in the UK. My understanding from scandi and soviet friends is that you switch your heating on when it gets cold in October and it remains on until it gets mild in April. We don't do that in the UK because that would cost a lot of money. We wait until it is cold before we put the heating on, we switch it off if we will be out of our houses all day. It is considered wasteful to have the heating on but to open windows for fresh air.

Our houses are small compared to Europe. I've lived in lots of homes where I had no space for a tumble dryer so had to dry washing inside as it rains for weeks on end. Very few laundrettes around.

It could be because in cold climates there is less moisture held in the air so Sweden is colder but drier.

I think this is part of the answer.

Certainly where I live in Scotland it is warmer and wetter - all our nice Edwardian sandstone buildings are going green with algae - never happened in the past.

I haven't lived in a house that has mould, but they've all been heated, ventilated and cleaned appropriately.

Modern double glazing and draught proofing retrofitted to older houses causes issues too - old houses (with fireplaces) were designed to have a few draughts, as this enabled the fire to burn and for the smoke to be drawn up the chimney. This also allowed the moisture to escape. Now we block everything up so there are no draughts at all, and that means mould.

For new builds, the issue can be what they're built on - near me, the land is often swampy, so was always farmland or planted with willows and the like to dry the land naturally. Now though, the land has houses built on it and the trees are felled, so many of the new estates near me have all sorts of problems which only come to light a few years after they're built when the land reverts to swamp.

Don't some of the Scandinavian counties have district heating rather than boilers in each house like we do here?

There is a much wider variety to heating sources in Scandinavia compared to the UK. Definitely don't see any gas boilers. The most common heating for a house where I live is probably geothermal heating now. If you are in an apartment it's district heating. Heating is also always (I think) included in your rent or service charge so there is no incentive to keep your place cold to save money.

I found damp in the corner of one of my rooms. Turned out the window was rotten where it meets the brick, water was getting into the cavity, and the insulation in the cavity was holding the water.

I have those little disposable dehumidifiers on every windowsill, it’s surprising how much they catch.

I can't work out what the difference is when two similar houses, lived in in exactly the same way, why one gets mould and the other doesn't.

The house I currently rent has mould issues, and I use it the same was everywhere else I've lived as an adult (10 or so properties in 25 years). I cook with the kitchen door closed and the window wide open (so it's freezing in winter), after showers the windows are wide and the bathroom door closed until all the steam has gone, and laundry is dried in one small room with a dehumidifier on.

It's late 60s however, which does seem to be an unfortunate decade for buildings that have mould issues. I think the construction of this house is very poor, but as a renter, there are no options in my town to move. All my other homes have been Victorian up to 1920s, never had a problem before.

Ime the amount of sunlight that hits a house makes a difference so shading trees could make it damper.

Lack of adequate ventilation especially in post 1970s buildings. Open some windows and dont block chimneys and air vents.

Because people don't open windows enough and dry clothes indoors.

I doubt they open all their windows and hang clothes on the line in Swedish winter!