Healthy Homes

Hazard assessment

Use this tool when a customer reports mould, or when logging findings after a visit. Answer the questions to see the hazard rating and prompts for further action.

Optional
1. Which rooms are affected?

Pick all that apply. The matrix is driven by the worst-affected room.

Worst-affected room

You've selected more than one room. Which has the most severe mould?

2. What is the highest vulnerability level in the household?

Pick the customer with the highest vulnerability.

More detail

Customers

  • No known respiratory or immune conditions
  • No children under 5
  • No older customers
  • No pregnancy concerns

Indicators

  • Cosmetic mould only
  • No ongoing complaints of illness
  • No evidence of rapid mould progression
  • Property remains safely occupiable
More detail

Customers

  • Children aged 5–14
  • Early-stage complaints without medical intervention

Symptoms

  • Mild throat irritation
  • Occasional coughing
  • Minor skin irritation
  • Watery eyes
  • Mild headaches
More detail

Customers

  • Customers with asthma
  • Customers with allergies
  • Young families with repeated respiratory complaints
  • Customers with GP involvement regarding symptoms

Symptoms

  • Persistent coughing
  • Asthma aggravation
  • Eczema flare-ups
  • Repeated chest infections
  • Allergic reactions
More detail

Customers

  • Children under 5
  • Pregnant customers
  • Customers over 75
  • Housebound or mobility-impaired customers
  • Customers with chronic respiratory disease
  • Customers with COPD
  • Customers with severe asthma

Symptoms

  • Difficulty breathing
  • Increased inhaler use
  • Reduced mobility due to environmental conditions
  • Higher susceptibility to infection
  • Sleep disruption and reduced wellbeing
More detail

Customers

  • Immunocompromised customers
  • Customers undergoing chemotherapy
  • Organ transplant recipients
  • Customers recently discharged from hospital with respiratory illness
  • Customers with severe uncontrolled respiratory conditions
  • Cases involving repeated hospital admissions linked to property conditions

Symptoms

  • Medical evidence linking symptoms to housing conditions
  • Severe respiratory distress
  • Unsafe sleeping conditions
  • Extensive contamination affecting daily living
3. How much mould is present?

Estimate the worst affected area in the property.

More detail

Small isolated patches of mould, generally less than A4 paper size, confined to corners, window reveals, silicone seals, or cold bridge locations.

Typical examples

  • Small mould spots around windows
  • Localised condensation mould behind furniture
  • Minor bathroom ceiling spotting
  • Light mould growth on sealant

Typical characteristics

  • Limited spread
  • Surface level only
  • No evidence of saturation or structural damage
More detail

Visible mould affecting larger wall or ceiling sections, commonly within bathrooms, kitchens, bedrooms, or living rooms.

Typical examples

  • Multiple patches across one wall
  • Mould extending behind furnishings
  • Persistent condensation damage
  • Black mould affecting corners and ceiling junctions

Typical characteristics

  • More established growth
  • Recurrent complaints or previous treatments
  • Possible early plaster deterioration
More detail

Large-scale mould contamination affecting multiple surfaces within a room, or wall or ceiling coverage of around 3–5 m², roughly twice the size of an interior door.

Typical examples

  • Full wall coverage 3–5 m²
  • Extensive bedroom mould growth
  • Multiple walls or elevations affected

Typical characteristics

  • Strong odour may be present
  • Surface deterioration likely
  • Persistent moisture source probable
  • Repeated treatment failure common
  • Customers may be unable to manage cleaning themselves
More detail

Heavy mould contamination affecting living rooms, bedrooms, or multiple structural surfaces including walls, ceilings, furnishings, and belongings.

Typical examples

  • Extensive black mould throughout occupied rooms
  • Saturated walls and ceilings
  • Mould affecting beds, clothing, or soft furnishings
  • Ongoing leaks or penetrating damp contributing to growth

Typical characteristics

  • High spore presence likely
  • Property conditions may be partially uninhabitable
  • Strong odour and visible deterioration
  • Health complaints commonly reported
  • High likelihood of underlying building defect
More detail

Extensive mould contamination affecting multiple rooms or widespread areas throughout the property, often combined with chronic dampness or structural defects.

Typical examples

  • Multiple bedrooms and living spaces affected
  • Severe penetrating damp with mould spread throughout property
  • Structural moisture saturation
  • Repeated historic failures to resolve issue
  • Customers unable to safely occupy parts of the home

Typical characteristics

  • Significant damage to finishes and possessions

Outcome

Answer the questions to see the recommended action.
Reference matrix

The selected combination is highlighted.

  • Mould in a kitchen or bathroom is capped at Non-regulatory: Medium unless vulnerability is High or Critical.
  • Mould only in porches, cupboards or outbuildings is capped at Non-regulatory: Medium regardless of vulnerability or extent.
Healthy Homes hazard assessment · v2.2 Aligned with Healthy Homes Hazard Matrix V6 Decision-support only · Always apply professional judgement