Damp and mould
There are several reasons your home might be suffering from damp and mould. It is surprising how few reasons are related to major building defects.
This page gives you the information required to understand and remedy the problem, and when to call the council for help.
The first questions to ask yourself about the problem
- Does the damp (not mould) get worse after rain? If it does you might have an unidentified defect with the weather tightness of your home
- Is the damp or mould in several places throughout your home? If yes then this might indicate you have a condensation problem. Please review the remainder of this page
- Does the damp or mould get worse in the colder months? If yes then this might indicate you have a condensation problem. Please review the remainder of this page
- Are the kitchen and bathroom extract fans clean and functioning properly? Extract fans can be easily cleaned and checked they are working. Please review the remainder of this page with particular attention to item 9
- Do you ventilate your home by opening windows or window trickle vents? Passive ventilation is a particularly effective way of controlling damp and mould. Please also review the remainder of this page
- Do you maintain a healthy temperature level within your home particularly in the months with colder mornings and evenings when you might be at home the most? Maintaining a healthy temperature within the home is crucial not only for stopping damp and mould but for the general health of the occupants. Please review the remainder of this page
- If applicable is the loft space insulated between 150mm and 250mm? Insulation helps to keep your home warm. If it is less than 150mm you might want to consider contacting the council to have your loft insulation topped up
What is condensation?
Moisture is absorbed into the warm atmosphere of your home, and when your home cools down the moisture condenses on cool surfaces. The effects of condensation are often underestimated and can over time cause damage to our homes.
The major difference between condensation and other forms of dampness is that you have the ability to reduce or solve the problem just through changing behaviour in your home.
An average family of 4 to 5 people can produce up to seventeen litres of water vapour per day.
This can be from drying wet clothes on radiators, having hot baths or showers, boiling kettles, cooking and of course breathing. That is 3.5 litres per person on average.
Common sign of condensation
The common sign of condensation is water collecting on the inside of windows, but it can form on any surface such as walls, and it may not be noticed until damage has already been caused.
The most vulnerable areas will either be rooms where a large amount of moisture is produced, i.e. bathroom or kitchen, or on cold surfaces in other rooms where this moisture can travel to.
Moisture moves around the home through a process called diffusion. Diffusion occurs if a part of your home has a higher moisture level than another part, such as the movement of moisture from the bathroom to the bedroom after a hot shower has filled the bathroom with steam.
The diffusion process
Diffusion happens even if there is no air movement at all. Just as heat travels from a hot space to a cold space, water vapour will travel from a space with a high moisture concentration to a space with a lower moisture concentration. Cold air almost always contains less water than hot air, so diffusion usually carries moisture from a warm place to a cold place.
In recent times condensation based damp has become a bigger problem in our homes which is largely the result of improved standards of insulation, double glazing and draught proofing in properties. Although this gives us the benefit of better heat retention, it can also lead to a reduced amount of natural air ventilation. You might choose to follow the advice on this page to help ventilate your home.
What can I do?
There might be an issue with the cost of living or rapidly increasing fuel costs leading to residents being unable to heat their homes to a healthy level, leading to more cool areas where condensation can form. It is worth investigating any available Government initiatives regarding cost of living support payments or contacting energy providers for advice.
Rarely, a building defect which might have gone unnoticed for a while could let moisture penetrate into the property such as a pipe leak or a roof leak. This moisture might then evaporate into the air and condense onto cold surfaces, however the evaporation process from these types of defects is slow and so condensation from these sources of moisture is limited.
Damp and mould from building defects are more likely to be visible in the locality of the defect so it is worth following the advice within this booklet before reporting any issue to Qualis. If you are suffering with damp or mould in your home there are a simple measures you can take right away even if you’re waiting for an inspection or a repair. Wipe down windows and window frames each morning but wring out the cloth rather than drying it on a radiator.
Without adequate ventilation and heating, condensation may result in unhealthy living conditions with the possibility of unsightly black mould growth, peeling decorations, damage to clothing or fabrics, rotting of materials and an unpleasant musty damp smell within a property if left unmanaged.
Wipe down the affected surfaces like walls, skirtings, windows and sills and clean with a mould cleaner as soon as mould appears. Follow the manufacturer’s instructions precisely and ensure that the product is safe for you to use. It is better to dry-clean mildewed clothes, or shampoo mildewed carpets because disturbing mould by brushing or vacuum cleaning can increase the risk of respiratory problems if mould spores become airborne. Most good home improvement stores and supermarkets supply products to remove mould.
What other actions can I take?
- Pull wardrobes, beds and furniture away from walls especially outside walls, and keep tops of wardrobes clear, to allow air to circulate. The cause of damp behind your furniture is nearly always condensation. Water builds up in the air, this moisture-rich air will get trapped behind your furniture. Airflow is not exactly great down the back of your sofa, bed or wardrobe, so the moisture builds up on cold surfaces and festers. Then it turns into damp and then mould propagates
- When cooking keep lids on saucepans, close doors and use the extractor fan. Most electric fans continue working automatically when their sensor detects humidity. Extractor fans are cheap to run and use less energy than a standard light bulb.
Moisture laden air can easily move around your home to other rooms and condense on the colder surfaces so keeping doors closed especially the kitchen and bathroom whilst bathing or cooking will help eradicate damp and mould. You should consider installing an extract fan if you have damp and mould in your kitchen or bathroom and do not have an extract fan
- Keep bathroom doors closed when bathing and open windows slightly afterwards or leave the fan running. Most council electric fans continue working automatically when their sensor detects humidity
- Avoid drying clothes on radiators or on airers unless ventilation is increased radically. Ideally clothes are not dried in this way however, if you dry clothes indoors it is best done within the bathroom on an airer with the door shut and the fan left on. Most electric fans continue working automatically when their sensor detects humidity
- What about my condensing tumble dryers? Condenser dryers use heat to dry clothes, and this heats the surrounding air around the appliance. This warm air is likely to be moist, and if there are any cool surfaces in the room, condensation will occur. This could be anything from windowpanes to tiles or even other appliances.
Although a condenser dryer does not need a hose to remove the moist air it produces in the same way as a vented tumble dryer, there will still be a great deal of warm air circulating around the dryer. This means that whatever room your condenser dryer is situated in can become quite warm. You might also notice some condensation appearing while your dryer is running.
To prevent the condensation turning into damp and causing problems, it is a good idea to position your condenser dryer in a room where the air can circulate. A well ventilated room will minimise the amount of condensation and prevent the air from getting too warm
- Open windows regularly to allow air to circulate and keep window trickle vents open for background ventilation. Windows that are opened for up to an hour each day especially after bathing or cooking helps moist air escape
- Keep the property moderately heated (with ventilation). It is important to get the right balance between heating and ventilation. The more humid the air is in your house, the more energy it takes to warm your house because it is also warming the water within the air. This means it will be more expensive to heat your home! When you open your windows it may seem that you are losing heat and allowing cool air to enter your home.
However, this actually lets moisture laden air out and dry air in. Dry air is cheaper to heat than moist air. Keeping room temperatures above 15°C will help reduce condensation forming on external walls. A suitable level of ventilation will allow the moist air to escape without making occupants uncomfortable by causing draughts and making the room cold. It may be quite difficult to strike the right balance. It is for this reason many homes have built in ventilation measures such as trickle ventilators and extractor fans.
It makes sense that people want to save on heating costs, but one of the best mould prevention techniques is keeping your home at the right temperature and ventilated. Avoid rooms cooling completely below 15°C. It is recommended that the ideal temperature for a living room is 20°C and for the bathroom kitchen and bedrooms 21 to 23°C
- Avoid the use of bottled gas heaters. Certain other heating methods such as using bottled gas heaters present a fire hazard but also add significant amounts of water into the air, water being a by product of burning these fuels so the use of these should be avoided
- Try to clean fans and check they are working correctly every 4 to 6 months. A fan free from fluff, dust, dirt and grease should mean it will operate efficiently extracting moist air. It is worth cleaning fans to prevent the rapid build up of dirt. To make sure they are operating correctly, you might try placing two sheets of toilet paper over the internal vent and the fan should be able to hold the paper in place if it is functioning properly
- If you have a fish tank – make sure it has a lid otherwise water will evaporate causing excess moisture in the air
What about healthy humidity?
A good range of indoor humidity within your home for comfort and health is between 30-60% during cooler months of the year. Mould is likely to occur if the relative humidity indoors is 70% or more for prolonged periods of time.
Keeping humidity levels under 50% also helps to minimise or control dust mites. But it is also possible to live in a house that is too dry!
Humidity levels below about 30% lead to dry skin and nasal passages, increasing the potential for respiratory illnesses. It is worth buying a low-cost humidity meter from a hardware store and track how humid the air is in your house?
You might be surprised at how quickly it can change, from morning to night, from room to room, and as the weather changes.