Business · 4 min read · Updated 6 November 2026
Mould in offices and workplaces: employer duties and what to do
The legal framework
Under the Health and Safety at Work etc. Act 1974, employers must protect the health of employees and others affected by their work, so far as reasonably practicable. The Management of Health and Safety at Work Regulations 1999 require a risk assessment. The Workplace (Health, Safety and Welfare) Regulations 1992 set specific duties, including that workplaces and equipment are maintained in good repair, enclosed workplaces are ventilated by a sufficient quantity of fresh or purified air, and workplaces are kept sufficiently clean.
The Control of Substances Hazardous to Health Regulations 2002 (COSHH) cover biological agents where exposure arises from the work itself, for example for cleaners or contractors removing mould, so anyone doing the work should have suitable controls and protective equipment.
Where mould turns up in workplaces
- Basements, archives and storerooms with poor ventilation
- Kitchens and staff toilets with weak or broken extract
- Around windows in older office buildings with single glazing
- Ceiling tiles stained by roof leaks or air conditioning condensate
- Behind wall-mounted displays and furniture on external walls
- Gyms, changing rooms and showers
- Units that have been vacant and unheated for a long time
Step-by-step response for employers
- Record the report, location, size and any staff health concerns
- Restrict access to badly affected rooms if needed
- Find the cause: leak, condensation, failed ventilation or air conditioning fault
- Notify the landlord or managing agent in writing if the cause is in their repair area
- Arrange cleaning and treatment by people with suitable equipment
- Replace water-damaged ceiling tiles, carpets and plasterboard rather than cleaning them
- Check ventilation rates and HVAC maintenance records
- Re-inspect after the work and keep the records with your risk assessment
Staff who raise concerns about mould are raising a health and safety issue. Respond promptly and keep them informed about what is being done.
Who pays: landlord, tenant or service charge
| Situation | Typically responsible |
|---|---|
| Full repairing and insuring lease of a whole building | Tenant, for repairs and cause |
| Multi-let building, leak from roof or common parts | Landlord, often recovered through the service charge |
| Mould from tenant's own kitchen or shower installation | Tenant |
| Mould from building-wide HVAC managed by landlord | Landlord or managing agent |
| Cleaning to protect staff while repairs are arranged | Employer, as part of health and safety duties |
Lease wording decides the final answer, so check the repairing covenants and service charge provisions, and get advice on anything significant. Dilapidations claims at lease end often include damp and mould damage, so dealing with it early can also save money later.
Ventilation in modern offices
Approved Document F guidance for new and refurbished offices typically expects around 10 litres of fresh air per second per person, and the Health and Safety Executive encourages the use of carbon dioxide monitors to identify poorly ventilated areas. Rooms that are partitioned off, such as new meeting rooms, are a common blind spot, because they can end up with no supply or extract. Rising CO2 readings and stuffy rooms usually go hand in hand with higher humidity. When new rooms are created with partitions, ask the fit-out designer to confirm how each room will be ventilated and whether the existing air conditioning or mechanical ventilation can cope. Adding a transfer grille, a ducted supply or a local extract fan at the design stage costs far less than tackling condensation and mould once the room is in use.
Reducing the risk long term
- Include mould and damp checks in routine premises inspections
- Service air conditioning and clear condensate drains
- Fix roof and gutter leaks quickly
- Keep extract fans in kitchens and toilets working
- Keep some heat in vacant areas over winter
- Avoid storing paper and textiles against cold external walls
Vacant offices, shops and units
Commercial premises left empty over winter are particularly prone to mould. With no heating, no people and no ventilation running, humidity rises, cold surfaces collect condensation and small leaks go unnoticed for months. Insurers often require regular inspections of unoccupied buildings, and some policies have conditions about heating, water supplies and checks. Read the policy terms carefully, because a claim can be refused if they are not followed.
- Inspect at least weekly, or as your insurer requires
- Keep low background heat and some ventilation on
- Drain down water systems if the building will be empty for a long time
- Check roofs and gutters after storms
- Move stored paper, furniture and stock away from external walls
Dealing with mould before a new occupier moves in, or before handing back a lease, avoids disputes and delays later.
Frequently asked questions
Can staff refuse to work in a mouldy office?
Employees can raise concerns and, in serious cases where they reasonably believe there is serious and imminent danger, they have legal protections. In most cases the practical answer is for the employer to restrict access to affected rooms, arrange cleaning and fix the cause quickly. Staff can also contact the Health and Safety Executive or local council if concerns are not addressed.
Who enforces mould problems in workplaces?
Depending on the type of business, health and safety in workplaces is enforced either by the Health and Safety Executive or by the local authority environmental health team. Offices, shops and many leisure premises are usually enforced by the local council, while factories and construction sites fall under the HSE.
Do mouldy ceiling tiles need replacing?
Usually yes. Ceiling tiles are porous, and once mould has grown into them after a leak they are difficult to clean properly. Replacing them is normally cheaper and more reliable. Fix the leak first and check the void above for wet insulation, ducts or pipework before fitting new tiles.
workplace employers commercial property health and safety
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