The Housing Health and Safety Rating System (HHSRS) is the risk-based system used in England to assess health and safety hazards in homes. Councils use it when enforcing standards in rented housing, and it underpins the Decent Homes Standard for social housing. In 2026 new regulations brought a review of the system into force, with new statutory operating and enforcement guidance. Here is how damp and mould fits in.
21 hazards, down from 29
The review reduced the number of hazards from 29 to 21 by merging hazards that are statistically similar. Damp and mould growth remains a hazard in its own right — number 11 in the updated list, in the “physiological requirements” group alongside excess cold, excess heat, radiation, lead, indoor air pollutants and asbestos.
What the hazard covers
According to the operating guidance, the damp and mould growth hazard covers threats to health from house dust mites and mould or fungal growth caused by dampness and/or high humidity. It also covers threats to mental health and social wellbeing from living with damp, staining and mould — and threats to health from flooding.
The guidance lists the main issues an assessor looks for as water ingress from rising or penetrating damp, plumbing leaks, condensation, inadequate heating and insulation, and a low Energy Performance Certificate rating.
Who the hazard is assessed for
Unlike Awaab’s Law, HHSRS does not assess the risk to the people actually living in the home. It assesses the likelihood of harm to the most vulnerable age group for each hazard. For damp and mould growth, that group is people aged 14 and under. The guidance also identifies other groups at greater risk, including people with asthma, people sensitised to allergens such as dust mites, immunocompromised people, and pregnant women.
How it is scored
- Deficiencies. The assessor identifies defects in the home and which hazards they relate to.
- Likelihood. They judge the likelihood of harm needing medical attention over the next 12 months, compared with the national average for that type and age of home.
- Spread of harm. They consider the likely outcomes across four classes of harm — moderate, serious, severe and extreme.
- Score. These produce a hazard score.
After the review, scores of 1,000 or more are category 1 hazards and sit in the new High band. Category 2 hazards are split into Medium and Low bands. Councils must take appropriate action on category 1 hazards and have discretion over category 2.
Baseline indicators
The review introduced baseline indicators — a checklist of reasonable standards. Under “moisture and contaminant control” they include external elements being watertight and free of persistent dampness, drainage directing water away from the structure, and no room having observable damp or mould growth (or deteriorated finishes) over more than 5% of the wall or ceiling surface. Meeting the indicators does not guarantee a home is hazard-free, but they are a useful starting point.
HHSRS and Awaab’s Law are different tests
A home can be a category 2 damp and mould hazard under HHSRS and still present a significant risk of harm to a particular household under Awaab’s Law, which looks at the actual tenants. Awaab’s Law does not require an HHSRS assessment. Our reports make clear which framework is being applied.
Official guidance
HHSRS guidance collection (GOV.UK) · HHSRS operating guidance · Landlord and agent guide. Checked 10 November 2026. These updates apply to England; Wales has its own HHSRS regulations.
Need an assessment?
We carry out HHSRS assessments following the current official guidance, and specialist damp and mould surveys to diagnose the cause.