Home : Condensation And Mould : Index

Condensation and mould growth lead to miserable living conditions. Mould is an indication that moisture levels are above those acceptable, and its growth can affect your health and stain décor and furniture.

Condensation occurs when water vapour present is more than can be carried at the current temperature, and reforms to droplets on the coldest surface. Warm air can hold more moisture, which is why condensation is (mistakenly) associated with cold weather. Pockets of limited air movement, for example behind large furniture, can also encourage mould to grow, black spot mould, (or Aspergillus niger to give it its Latin name, as many surveyors will), being the most common, although white, pink and other colours can be seen as a result of condensation.

Mould growth in an alcove, discovered when a bookcase was moved.

Mould growth at low levels is often mistaken for rising damp, but the treatments are different. Mould is a surface problem, whereas rising damp comes up within the wall from the ground. The two can be present in a property which has had little or no maintenance carried out, but are not otherwise associated. Mould tends to like ‘clean’ water i.e that deposited by condensation, rather than that drawn up through the wall from the soil, as this is contaminated by ground salts.

If condensation is present sufficiently to cause the surface of the wall to absorb enough water, small ‘mushrooms’ can grow out of the wall. These are known as peziza, or plaster fungus. They are not of the same type of fungus that causes wood to decay, but they do indicate that the property has enough of a dampness problem to alert you to the possibility of other related issues.

Mould and Health

There is great concern regarding the effect of mould spores in the air on the health of you and your children. Generally speaking, mould spores, like pollen, are air-borne and everywhere, and do not affect those with robust health. Problems occur when mould is allowed to grow and produce spores in great numbers, and these can exacerbate problems in those suffering from asthma, or with respiratory or pulmonary conditions.

Toxic Mould

“Toxic mould” (Stachybotrys chartarum) has recently been making news, but like many a screaming headline, take it with a pinch of salt - it should not make you think that every bit of mould in your house is deadly!! Despite the worrying headlines, though, even in the USA there have been very few insurance claims for this, which puts it in to perspective! Toxic mould exacerbates existing respiratory and allergenic conditions, and is thought to have long term debilitating effects on health.

Generally speaking, toxic mould requires a lot more water than do the more commonly found moulds (like long standing and serious water leaks or flooding), and have a dark brown or black, slimier appearance than most. If you have cause for concern, call in a specialist surveyor. Some have access to a service which can DNA test mould samples to determine exactly which type it is.

Limiting Your Condensation and Mould

Modern living leads to a decrease in natural ventilation – we’ve sealed all of our doors and windows, and open fireplaces have gone. Then we’ve gone and added daily showers, cooking and constant kettle boiling - an average household puts 12 to 15 litres of water in to its air daily!

Put simply, good ventilation, steady background heating, and insulation of cold walls can greatly limit the conditions which lead to condensation. But is this always possible? Many houses are closed up all day due to security issues. And if you’re out at work for long hours, why would you heat an empty house?

Mould spores are everywhere. Whether they find somewhere suitable to settle and grow can be interrupted by a canny householder. Whilst it would not be reasonable to expect anyone to totally change their living style, or spend a lot of money to control this problem, there are some steps you can take.

Reducing Moisture Vapour

This is a tricky one – can you stop washing or cooking? Reducing the moisture vapour produced is the first step in condensation control – get in the habit of opening the bathroom window after a shower or bath (maybe not during if it’s cold!) so that the moisture doesn’t stay in the house. Ensure tumble dryers are vented to the outside. If you don’t have an extractor, can the kitchen window be opened during cooking (close the door to the living room to keep the heat in there)? If you’re putting clothes on the radiators or a clothes horse, try to get the window in that room opened when possible.

Paraffin fires produce one litre of water for every litre of paraffin burned. Gas fires also add moisture to the air in a room. Air extraction is of double importance here as it removes fumes as well as moisture, and regular servicing of the fires ensures clean and efficient burning of the fuel used.

Methods Of Increasing Ventilation

Air bricks are not popular as they are sometimes thought to let in draughts, which does not improve your living comfort. Extractor fans are worth considering, as they can be positioned in the bathroom and the kitchen, thus removing moisture at source, and not allowing it to spread throughout the house. Some are manually switched on, and others have humidity sensors and automatically come on when required.

Heat exchange units mechanically draw fresh air in from outside, at the same time as drawing stale air out of the room. The warmer stale air is used to increase the temperature of the fresh air, and some units come with heaters built in to use when the outside temperature is extremely cold. Heat exchange units are a great idea as they encourage regular air changes without draughts. They also cause no security problems and can be switched on to boost when required.

It’s worth mentioning here air bricks that ventilate the area below wooden floors – if humidity builds up here it can lead to timber decay in joists or floorboards. Check that the air bricks are not blocked. If you have timber floors and no air bricks, get them put in!!

Mould Treatments For Walls

Painted surfaces can be treated with special wall washes which remove mould, although often some staining is left. Additives are available which can be mixed in with standard emulsions you may already have, to form a paint which is then resistant to further mould growth. This can be an inexpensive treatment for a wall, and this type of paint can also be used over some wallpapers. Ready-to-use anti-mould paints are also available.

Always buy an anti-mould or mould resistant adhesive and grout for wall tiles.

Whilst mould spores are everywhere, you can do a lot to make your home an extremely inhospitable place for them.