Having read a bit about damp and mould issues in poorly heated homes, I was wondering whether this was an issue for Britain in the past, where few houses have central heating systems. Presumably the British climate hasn't changed that much in terms of humidity in winter, so mould was supposed to be an issue for them? I have read stories of older people saying their windows were icy when they were a kid, but I haven't heard people complaining their houses were mouldy.

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    When you ask about "Britain in the past", you're specifically asking about the 20th Century (as per the tag)?
    – Steve Bird
    Commented Aug 23, 2022 at 14:01
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    Each room (including the bedrooms) would have a fireplace. Even if there wasn't a fire in them, ventilation wasn't a problem! Depending upon your wealth/size of house, there would be one or more fires downstairs all day in winter, possibly a range for cooking. Mould requires fairly high humidity and some warmth. I was in my teens when we first had central heating, I well remember coal fires.
    – user55099
    Commented Aug 23, 2022 at 14:02
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    Older British houses are well ventilated... or as we say, draughty. And people had open fires, often in every room. Coal was cheap, and if you didn't have coal you could burn wood.
    – Ne Mo
    Commented Aug 23, 2022 at 21:42
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    Judging from my youth, houses were too ruddy cold to grow mould! ;-)
    – TheHonRose
    Commented Aug 24, 2022 at 7:57
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    @MCW oh, servants were part of the problem. They increase condensation, because they will keep breathing...
    – Ne Mo
    Commented Aug 24, 2022 at 9:25

3 Answers 3


The answer has not much to do with history, but needs deep-diving into structural engineering and interstitial condensation. The shortest and over-simplified version might be this from the Wikipedia article about humidity:

Common construction methods often produce building enclosures with a poor thermal boundary, requiring an insulation and air barrier system designed to retain indoor environmental conditions while resisting external environmental conditions. The energy-efficient, heavily sealed architecture introduced in the 20th century also sealed off the movement of moisture, and this has resulted in a secondary problem of condensation forming in and around walls, which encourages the development of mold and mildew.

In other words: older building materials were worse at insulating the buildings, but better at preventing wetness building up within the walls.



There's currently a slum-housing scandal in the UK due to the inquest into death of two year old Awaab Ishak:

Awaab died in December 2020 as a result of a severe respiratory condition. In 2022, a coroner at Rochdale coroner's court ruled that this was caused by prolonged exposure to toxic black mould in his home which had "inadequate ventilation and was not equipped for normal day-to-day living activities which led to excess damp and condensation"

(A late addition, and not a historical event but I thought it would provide some context.)

Original answer:

Damp was a major problem for the UK housing stock in use during the twentieth century:

House in Thomas Street. Back to back, two up, one down (i.e. a three-storey house with one room on each storey). Cellar below. Living-room 14 ft. by 10 ft., and rooms above corresponding. Sink in living-room. Top floor has no door but gives on open stairs. Walls in living-room slightly damp, walls in top rooms coming to pieces and oozing damp on all sides.

George Orwell - The Road to Wigan Pier (first published 1937)

There was a huge expansion in house building during the nineteenth century driven by the need to house workers during the industrial revolution. Construction was often cheap, quick and to poor standards which resulted in damp, mould, insect infestation (cf. The Road to Wigan Pier) and poor sanitation. Many of these buildings continued to be used, unimproved, well into the twentieth century. The lack of regulation was first addressed by the Public Health Acts of 1875 and 1878, and 1878 Building Act.

From the 1890s on, large scale slum clearance has been undertaken in an attempt to replace poor housing with new development, however improvements in accommodation often came at a cost of damage to communities.

It would be a mistake to assume that damp and mould are historical problems that are no-longer found in UK housing:

Tenants of one of England’s largest housing groups say they have been left for years in ‘uninhabitable’ homes as experts warn social renters could be left with long-term health conditions as a result of damp and mouldy properties.

From INews 28 March 2022

And also:

As a nation, Britain has a big problem with damp, it can not only cause damage to your home but if left for a long period of time, it can also cause problems to your health as well. According to Shelter, there are 1 in 5 renters who are affected by damp and mould in Britain. So why are mould and damp problems so common in British homes?

Timberwise, 25 January 2022


Open fires send a lot of hot air, their own fumes, and moisture up the chimney, and draw in cold air to replace it. The both need and provide ventilation, and that helps to some extent with damp. Condensation was still a problem.

By the late 20th century fireplaces might well have been occupied/replaced by gas fires. Unlike many modern gas fires they weren't room sealed* (i.e. you could actually touch the flames if you were stupid enough). Some vented up the old chimney, some smaller ones had no flue at all, so created moisture in the room. Air from outside was necessary whether there was a flue or not, through vents of some form, such as air bricks in the walls. My grandparents' house (Victorian) was like this is in the 1990s, with solid walls and single glazing. The windows had a lot of condensation on them in winter, but not the walls. Some of the windows in that house were louvred, and others sash; the former in particular could never be made to seal.

These fires could be fitted until surprisingly recently; I know of a house that has one in addition to gas central heating, complete with vents and chimney, and that was built about 25 years ago.

As a further intermediate step. some gas fires had a "back boiler" to heat water or even run central heating; in those cases the gas fire sat on the old hearth, with the boiler in the bottom of the chimney. I lived in a (30s-built) house in '99-02 which had hot water and rudimentary central heating done this way. That was the dampest house I've ever lived in, but also the mostly densely occupied; it struggled with condensation on the upstairs outside walls, leading to mould on things touching them long term.

* Many modern gas fires draw air through a flue in the outside wall behind them, and have a concentric exhaust. They have glass between the flames and the room, sealed to the metal housing.

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