Damp and Mould under the HHSRS and Redfearn Mould Testing Services

The Housing Health and Safety Rating System is all about the risks to health and safety and identifies the severity of any issues, rating them as follows: Class 1 – Extreme (including death and permanent paralysis), Class 2 – Severe (including cryptosporidiosis, asthma and lead poisoning), Class 3 - Serious (including rhinitis, sleep disturbance, gastro-enteritis), Class IV - Moderate (including benign tumours and regular serious coughs or colds).

Damp and mould growth under the HHSRS covers threats to health associated with the increased prevalence of house dust mites and/or mould or fungal growths resulting from dampness and/or high humidity within a property.

The likelihood of damp occurring within a property can be linked to:

·         Inadequate heating.

·         Inadequate insulation.

·         Inadequate ventilation.

·         Structural disrepair such as mortar and pointing damage, missing bricks or cracking to external walls.

·         Lack of or inadequate damp-proofing.

·         Inadequately sealed or installed facilities such as windows.

·         Disrepair to or inadequately installed pipework and defective rainwater goods and gutters etc.

·         Wrongly installed cavity wall insulation.

There are different types of damp, including rising damp, penetrating damp and condensation damp.

Rising damp occurs when water from the ground rises up through the bricks and mortar of a building via capillary action. The presence of mineral salts coming through the wall at low level can be detected using a salts test analysis. There may be staining and a tide mark up to approximately 1 metre above ground level on internal and external walls. Other potential causes such as leaking pipework, downpipes, splashing from gullies and water pooling. Rising damp requires the installation of a damp proof course and removal and replacement of damaged plaster.

Penetrating damp occurs when water penetrates internal the interior of a property. This can be caused by structural damage to roofs, chimneys, render or overflowing rainwater goods, defective windows, ground bridging and even cavity wall insulation bridging moisture across a cavity. In this case mineral salts can come through the wall, with staining and damage to wallpaper, plasterwork and paintwork etc. Unlike rising damp, black mould can be present. Dealing with penetrating damp requires the structural defects to be addressed and the removal and replacement of damage plaster and/or internal ‘tanking’.

Condensation dampness occurs when moisture-laden air condenses on colder surfaces. Condensation dampness appears as surface dampness and associated black mould growth, including on furniture and clothes and other surfaces. Frequently condensation dampness is blamed on tenant lifestyle, including lack of ventilation or failure to use ventilation provided. It can also be caused by inadequate heating, or insulation. The treatment for condensation dampness involves not only opening windows, but improving ventilation by ensuring adequate mechanical ventilation, adequate insulation, heating and airflow throughout the property (i.e. keeping belongings and furniture away from walls), ensuring appliances such as tumble dryers are vented appropriately.

Wet rot and dry rot affect timber. The former often creates a musty smell and cracked, softened and distorted timbers. The source of the water should be eliminated and the affected timbers replaced. Dry rot on the other hand causes timber to darken and crack with the appearance of a white cottony mycelium (fungi). Again, removal of the water source and affected timber is necessary, coupled with fungicidal treatment. Dry rot can spread very easily and quickly.

The Who Guidelines for Indoor Air Quality (Dampness and Mould) indicate that “the prevalence of indoor damp is estimated to be in the order of 10–50%. It is highest in deprived neighbourhoods, where it often significantly exceeds the national average. High air humidity, condensation and water damage promote the survival and growth of dust mites and fungi, resulting in increased exposure to mite and fungal allergens and fungal toxins and irritants. Damp building materials may increase their chemical degradation, resulting in more emissions of volatile organic compounds, including formaldehyde. As dampness is more likely to occur in houses that are overcrowded and lack appropriate heating, ventilation and insulation (Institute of Medicine 2004), the prevalence of indoor damp in low-income communities can be substantially higher than the national average. For example, in a study of 1954 young mothers in the United Kingdom, those who lived in owner-occupied or mortgaged accommodations (relatively affluent) reported damp (52%) and mould (24%) significantly less often than those who lived in council houses or rented accommodations (relatively deprived), 58% of whom reported damp and 56% of whom reported mould.”

The HHSRS is concerned with the potential impact on health due to dampness in buildings from an increase in dust mites, fungus, mould and others. Dust mites, fungi and bacteria all thrive in moist conditions.  There is a close association between damp indoor environments, dust mites, allergens and asthma. Dust mites thrive in higher relative humidities and therefore damp houses can increase exposure to dust mites and their associated allergens. Along with their potential health hazards, fungi can have a devastating impact on the wooden elements of buildings and other structures (see dry/wet rot above) and many species of mould can be irreparably damaging to health, particularly in those with suppressed immune systems or respiratory issues.

It is therefore imperative that experts understand what species of mould they are dealing with in any property they inspect. All of our experts are equipped with mould testing kits and we use a laboratory dedicated to identifying the types of mould found on site and reporting that information back to our instructing solicitors and their clients. Since we first started testing in 2021 the incidence of significantly hazardous mould types has been shocking with decanting of tenants proving necessary in some instances. The serious damage to health that might be caused by mould cannot be underestimated, particularly for those who are susceptible, young children and the elderly.