Damp And Mould

A Guide to Damp and Mould - Causes and Prevention

Dampness and mould growth are one of the biggest housing issues and can be responsible for a number of potentially serious health problems, including asthma, as well as causing damage to the property, furniture, furnishings and clothing, etc. Dampness can increase dust mites, make the home colder as it lowers temperatures, and cause mould growth.  This leaflet has been produced to help residents that are affected by it.

A note on mould

Mould is a type of fungi which grows in damp conditions and produces spores which lead it to spread. These spores can also be inhaled which is unhealthy. As well as the risk to health, mould in the home is unsightly and can cause embarrassment and negatively affect mental wellbeing.

What are the causes of damp?

It is important to first establish the cause of damp so that the right steps can be taken to resolve it. If you are a tenant, you should report any damp and mould to your landlord who has a responsibility to investigate and take appropriate steps to deal with and prevent damp and mould. The main causes are condensation, leaks/penetrating dampness and rising dampness.

Condensation

There is always some moisture in the air even if you cannot see it. The warmer the air, the more moisture it can carry. When it can't hold any more moisture and is 'saturated', it forms water droplets (condenses) when it comes into contact with cold surfaces, such as walls and windows. Condensation occurs mainly during cold weather (raining or not) as colder air holds less moisture before it becomes saturated and condenses in contact with colder surfaces. It is often found on colder (external) walls, on and around windows and in corners and behind furniture where there is less air flow.

Condensation is the most common cause of dampness in the home. It can result from one or usually a combination of factors such as inadequate heating, ventilation or insulation, excess moisture being generated and overcrowding.

Leaks/penetrating damp

Leaks from faulty plumbing, leaking seals to baths, around windows, etc cause dampness directly in the property. External issues can cause water to seep in through the structure such as missing tiles to the roof, blocked or damaged guttering, downpipes or waste pipes or issues that cause water to flow from overflow pipes.

Rising damp

This occurs where water rises up from the ground through the floor or into the walls of the building where the damp proof course/membrane is missing, has failed, or has been 'bridged' (where water is able to 'bypass' the DPCs waterproof barrier). There is usually a tell-tale tide mark on affected walls and this would only occur at low level (up to about 1m from ground level).

How do I get rid of damp and mould?

Whatever the cause, mould should be removed from surfaces as soon as possible to reduce the likelihood of health effects and stop it spreading further. Use a damp cloth (to prevent spores from going into the air) and a suitable mould killer. You can buy products designed for this purpose or can use diluted bleach. Follow manufacturer's instructions and safety precautions (such as wearing gloves). More natural substances that have anti-fungal properties such as white vinegar, tea tree oil or grapefruit seed extract can also be used, diluted.

If the dampness is due to a leak or rising damp, repairs will need to be done, and property owners may need a damp specialist or reputable plumber to advise/carry out works. Once works are carried out, it can take a while (weeks or months) for the affected surfaces to dry out, and it may be advisable to hire a dehumidifier to assist the drying out process. In rented properties, landlords would be expected to cover the cost of hiring and running these. Re-decorating (and re-plastering if needed) should only be done when the drying out process has finished. If condensation is the cause, follow the advice below on how to avoid condensation.

How to avoid condensation

Heating

Homes should have permanently fixed, rather than portable heaters.They should be maintained in proper working order. The heating should be sufficient to properly heat the whole home, and should be controllable (e.g. room thermostat, thermostatic radiator valves).

More constant, low-level heating rather than short bursts of high heat is better to help prevent condensation.

Insulation

Insulation and draught exclusion to windows, doors and gaps not only helps keep the home warm and cuts fuel costs, but also cuts down on the formation of condensation by preventing lowering the temperature of the structure. Homes should (where appropriate) have the specified amount of loft insulation in accordance with Building Regulations, and cavity or solid wall insulation. It should be noted that some of the older forms of cavity wall insulation may not be effective and in some cases could even lead to damp problems by bridging the cavity.

Grants are available for insulation. See Action Surrey for further details and eligibility criteria Action Surrey.

Ventilation

Controllable ventilation is important to help remove moist air and ensure good air flow in the home. Bathrooms and kitchens where moisture is generated by bathing and cooking should have extractor fans (preferably humidistat which activate when moisture in the air reaches a certain level). If you have them, ensure they are working properly (a good test is if a piece of paper 'sticks' to the vent when it is on, then it is actively drawing air outwards). They need cleaning and servicing from time to time.

Windows should be regularly opened to ventilate. Most modern double glazed units are able to be locked in a slightly open position for ventilation whilst maintaining security, or have trickle vents. However, it's very important to ensure that windows are not left open for long periods during cold spells as this would allow the structure of the property to become cold, which can increase the formation of condensation. Rather, ventilation should be used to purge damp air following activities that generate moisture (cooking, bathing, drying washing, sleeping etc) and to allow good air flow.

Keep furniture away from walls and don't overfill cupboards. Adding vents to built-in cupboards and wardrobes will help air circulation.

Reduce moisture generation

• put lids on pans when cooking; ventilate the kitchen during and after cooking, and consider closing the door to avoid moist air travelling around
• ensure that vented tumble dryers (ones that don't have a condensing water container) are properly vented to the outside
• minimise the drying of clothes inside, but where necessary, have heating and ventilation on in the room where they are drying and close the door to avoid the moist air from travelling to other parts of the home
• avoid the use of calor gas or paraffin heaters which generate large volumes of moisture
• close doors to bathrooms when running/having baths or showers and ventilate well afterwards

For further information or advice please contact us

Environmental Health Residential Team
Spelthorne Borough Council, Council Offices,
Knowle Green, Staines, TW18 1XB

Telephone: 01784 446251

Email: eh.residential@spelthorne.gov.uk

Taking control of asthma for children and young people

Government guidance on damp and mould for landlords

For further information please visit the GOV.UK website for understanding and addressing the health risks for rented housing providers