A practical guide to preventing damp and mould

Have you ever wondered why mould is such a deal? Mould releases tiny spores in their thousands that are carried in the air – and these microscopic particles can trigger allergic reactions. The spores can cause itchy eyes and eczema, and also commonly contribute to the problem of respiratory conditions.

The effects can range from mild symptoms such as a stuffy nose, coughs and wheezes through to life-threatening asthma attacks and infections. A study by the US EPA attributed more than a fifth of national asthma cases to dampness and mould. In the UK, the NHS spends an estimated £1.4 billion annually on treating illnesses associated with cold or damp housing. ​Mental health is also impacted directly, whereby doctors have recorded more depression and anxiety in people living in cold and damp homes.

In 2020, Awaab Ishak, aged two, died because of exposure to mould, becoming the first person in the UK to have mould as the cause of death on his death certificate. This caused the UK government to take action, and Awaab’s law came into force in July 2023. The regulations oblige social housing landlords to investigate and repair complaints relating to mould within specified timescales.​

In September 2023, the UK government also produced guidance on damp and mould in the private rental sector. This applies to England and references the Housing Act (2004), which affords local authorities the power to take enforcement action on perceived hazards. Scotland also improved standards in March 2023, setting out statutory guidance for landlords regarding repair standards, and this comes into force on 1 March 2024. Internationally, there is varying legislation holding rental providers accountable, but discouragingly, the WHO has not published updated guidelines since 2009.

The Housing Health and Safety Rating System (HHSRS) places mould as a category 1 hazard. Mould is, therefore, in the same class as asbestos, carbon monoxide and lead. These carry the highest risk of causing the most serious harm. If a category 1 hazard is identified in the rental sector, the local authority has a duty to act against a landlord to try to solve the problem.

The risk of mould growth is at its highest in low temperature and high humidity conditions. This occurs often where there is poor insulation and faulty (or lack of) heating and ventilation systems. The first instinct people often have when dealing with mould is to clean it away. While this removes the surface issue, it is only a temporary solution. Painting over the mould is also ineffective in the long term.

Below are three practical steps that can be taken in new or existing homes to permanently remove the conditions that encourage mould growth:

Step 1: Remove the sources of dampness. Ensure there are no leaks or damage to pipes, window frames or the roof where water may enter the home. Aim to lower humidity levels to under 60% using a dehumidifier, wiping condensation from windows, placing warm jackets around cold pipes, and wiping down walls and tiles after a shower or cooking. You should also dry clothes outside, where possible, in the warmer months. If you need to dry clothes indoors for the winter period, invest in a heated airer that is more efficient than a tumble dryer. If you are considering tumble dryers, be mindful of their high energy demand and opt for a heat pump version if possible.

Step 2: Ventilation. This allows free-flowing air to remove moisture build-up. This means using extract fans in kitchens and bathrooms and opening trickle vents above modern windows. Purge ventilation (opening a window or door) for a short time can be used intermittently when a build-up of moisture cannot be removed through alternative methods. Most modern glazed windows can be placed in a trickle ventilation setting (using the little vents above the window) or in the slightly open-locked setting.

Step 3: Thermal comfort and insulation. Maintain the indoor temperature to a minimum of 17^oC at all times. Warming surfaces such as windows reduces the conditions for condensation to form. To decrease the energy cost associated with home heating, consider improving insulation such as loft or wall insulation upgrades or installing new draft-proof windows. However, as this can trap moisture indoors, ventilation must also be considered during the energy efficiency upgrades. All homes are advised to attain an Energy Performance Certificate (EPC) rating of C or above for health, cost, and environmental reasons.

Research shows that people who live in well-insulated and adequately ventilated homes are less likely to visit their doctor or be admitted to a hospital due to respiratory conditions. For further information on how to help prevent dampness and mould in your home, turn to the ‘BESA A practical guide to mould’ and ‘Part F of the Building Regulations (2021)’.

Please contact the Cundall Air Quality team for further information.