Mice in the office: what employers must do right now

If you spot mice in the office, act now. Isolate the affected area, stop using any exposed food or supplies nearby, and log the sighting with a time, date and location before it slips anyone’s memory. Notify facilities or the duty manager immediately, then call a professional pest controller rather than reaching for a supermarket trap. If food is stored or prepared in the space, treat temporary closure as a live option until a contractor has assessed the risk. Employers have a duty under the Health and Safety at Work etc. Act 1974 to keep the workplace safe for staff and visitors, and mice in the office are a direct test of that duty.

• Isolate the area and restrict access
• Stop using contaminated food, cups or supplies
• Log the sighting with time, location and evidence type
• Notify facilities or the duty manager
• Call a professional pest controller promptly
• Consider temporary closure if food handling is involved

Key Takeaways

Managing mice in the office successfully requires fast isolation and reporting on sighting, documented prevention, and a professional contractor working within legal and stewardship frameworks.

This article is general information, not a substitute for advice from a qualified lawyer. Consult a qualified legal professional about your own circumstances before acting on anything here.

Table of Contents

• Signs of mice in the workplace and what draws them in
• What are an employer’s legal duties when mice appear?
• Practical prevention checklist for office mice
• What to do when mice are confirmed in your office
• Monitoring, records and contracts that prove due diligence
• How BioWise approaches office mouse control
• The gap between office pest policy and office pest practice
• Get office mouse control sorted before it becomes a bigger problem
• Sources
• FAQ

Signs of mice in the workplace and what draws them in

Mice rarely announce themselves. Most offices catch on only once droppings or a smell give the game away, and by then a pair of mice can already be a small colony.

1. Droppings — dark, rice-grain sized pellets, often clustered near skirting boards or under sinks
2. Gnaw marks — on cardboard, cabling, skirting and food packaging
3. Grease or smear marks — dark smudges along walls and floor edges where mice repeatedly brush past
4. Nests — shredded paper, insulation or fabric tucked into quiet voids
5. Noises and odour — scratching in ceiling voids or wall cavities, and a faint musky smell in enclosed spaces

Check break rooms, storage cupboards, ceiling voids, service risers and loading bays first. These are the highest-risk spots because they combine warmth, quiet and proximity to food or waste. Mice are drawn in by food residues left on desks or in bins, unsecured waste, clutter that offers shelter, overgrown vegetation against the building, and any gap that gives easy access from outside.

What are an employer’s legal duties when mice appear?

The Health and Safety at Work etc. Act 1974 and the Workplace (Health, Safety and Welfare) Regulations 1992 place a duty on employers to ensure, so far as reasonably practicable, the health and safety of everyone using the premises. A rodent infestation left unaddressed can breach that duty, and it exposes the business to both regulatory action and reputational damage.

• Keep a written record of sightings, actions taken and contractor visits
• Cooperate fully with environmental health inspectors if they visit
• Establish who holds responsibility: landlord, tenant, or managing agent, and confirm it in the lease
• Treat any food storage or preparation area with the same seriousness as a commercial kitchen

Where food is stored or prepared on site, even in a small kitchenette, Safer Food, Better Business guidance requires more stringent hygiene procedures during an active infestation, including two-stage cleaning and, in some cases, temporary closure until control is confirmed.

Pro Tip: If your office has any shared canteen or kitchenette, treat it under SFBB rules from the first sighting, not after a second one. Regulators judge response speed, not just outcome.

Responsibility for pest control in a leased office building often sits with the landlord for common areas and the tenant for demised space. Get this clarified in writing before an infestation forces the conversation.

Practical prevention checklist for office mice

Prevention beats reaction every time, and it costs far less than repeated emergency call-outs. Build these tasks into your facilities schedule rather than treating them as a one-off clean-up.

1. Daily sanitation — store food in sealed containers, wipe down desks and shared kitchen surfaces, empty bins nightly and clean appliance crumb trays weekly.
2. Desk-food policy — ban food storage in desk drawers overnight and require staff to clear perishables before leaving.
3. External waste management — use sealed external bins with tight lids, keep them away from the building where possible, and remove any harbourage such as stacked pallets or overgrown shrubs.
4. Exclusion works — inspect for gaps around pipework, vents and doors; mice can squeeze through openings the width of a pencil, so combine steel wool or copper mesh with sealant rather than relying on expanding foam alone, which they can gnaw straight through.
5. Door sweeps and thresholds — fit sweeps to external and loading-bay doors where daylight is visible underneath.
6. Staff training and reporting — brief teams on what a sighting looks like and give them a simple route to log it, whether that’s an email address, a facilities ticket, or a physical logbook by reception.
7. Inspection cadence — run daily visual checks in kitchens and storage, monthly walk-rounds of the wider office, and quarterly professional inspections with follow-ups triggered by any confirmed activity.

A waste management system that keeps bin schedules and external storage consistent removes one of the biggest attractants before it becomes a problem. Good housekeeping and sealed access points remain the most cost-effective long-term defence against rodents, well ahead of repeated reactive treatments.

Pro Tip: Walk the building’s perimeter after dark once a season with a torch. Fresh droppings and gnaw marks show up far more clearly against artificial light than they do in daytime office traffic.

What to do when mice are confirmed in your office

Once mice are confirmed, the response needs structure, not panic. A clear sequence protects staff and gives you a defensible record if anyone asks how the situation was handled.

• Restrict staff access to the affected area and brief anyone who needs to enter
• Provide gloves and appropriate PPE to cleaning staff before they touch contaminated surfaces
• Never let untrained staff handle or move bait boxes set by a contractor
• Discard any food or packaging that shows signs of contamination

A reputable contractor will survey the site, identify entry points and nesting areas, and propose a treatment plan with a realistic timeline, usually a few visits over several weeks rather than a single call-out. Cleaning should follow a two-stage process: clean surfaces first to remove debris, then disinfect, exactly as SFBB guidance recommends for active rodent infestations. Rodenticides carry strict controls, and HSE guidance on stewardship makes clear they should be used only by trained professionals within an Integrated Pest Management framework, never as a DIY fix.

Monitoring, records and contracts that prove due diligence

A pest logbook is your evidence trail if an inspector or a client ever asks how seriously you take the issue. Record the date and time of each sighting, the exact location, the type of evidence found, the staff member who reported it, and any photos taken. Note every contractor action against the same log.

Monitoring stations and trap records, checked on a set schedule, turn anecdotal sightings into a documented pattern a commercial contractor can act on quickly.

Keeping this logbook alongside a scheduled maintenance contract gives you a paper trail that stands up to scrutiny, whether that scrutiny comes from environmental health, a landlord, or a nervous client walking through your office.

How BioWise approaches office mouse control

Biowise Pest Control Maintenance Services has worked with London businesses on pest management since 2010, building a client base of over 600 across the city, with an emphasis on eco-conscious treatment methods.

A reputable contractor’s visit should always include:

• A full survey of entry points, nesting areas and high-risk zones
• Exclusion works to seal gaps before treatment begins
• Targeted treatment using methods appropriate to the site
• A written evidence log and a scheduled follow-up visit

Pro Tip: Before signing a contract, ask any pest control provider about their rodenticide stewardship practices and whether their technicians hold recognised pest management qualifications. A vague answer is a red flag.

When choosing between providers, check for insurance cover, clear contract terms on visit frequency, and a written commitment to Integrated Pest Management rather than blanket poison use.

The gap between office pest policy and office pest practice

Most offices have a pest control clause buried in a facilities contract somewhere, and most managers have never read it. That gap is the real risk, not the mice themselves. The conventional advice tends to stop at “call a professional,” which is correct but incomplete. It skips the part where a logbook, a monitoring schedule and a clear escalation path are what actually protect a business when an inspector or a client asks hard questions.

I’d argue the sequencing matters more than most guidance admits: exclusion and sanitation should happen before treatment is even needed, not as an afterthought once mice are confirmed. Businesses that wait for a sighting to start sealing gaps are always working reactively, and reactive pest control costs more in the long run than a quarterly inspection ever would.

Prioritise the boring stuff first: sealed bins, a working logbook, and a contractor relationship you’ve already vetted before you need it urgently. The dramatic response plan matters less than the unglamorous groundwork that stops you needing one.

— Ana Hasula

Get office mouse control sorted before it becomes a bigger problem

Biowise Pest Control Maintenance Services gives London office managers a fixed point of contact instead of a scramble through directory listings when mice show up unannounced. Where a one-off call-out leaves you starting from scratch at every sighting, a monthly maintenance contract keeps exclusion works, monitoring and documented visits running continuously, so your pest logbook fills itself in as part of the service rather than becoming another task on your desk.

Biowise Pest Control Maintenance Services has supported numerous London clients since 2010, including offices, restaurants and housing associations, with eco-conscious treatment methods and transparent reporting after every visit. If your office needs a survey or an ongoing contract, explore commercial pest control services built specifically for London businesses, or get in touch for a tailored quote today.

Sources

• Workplace health, safety and welfare. Workplace (Health, Safety and Welfare) Regulations 1992. Approved Code of Practice and guidance L24
• Safer Food Better Business – Managing an active rodent infestation (local authority/SFBB guidance)

FAQ

What is the five-day rule with mice?

There is no official “five-day rule” in HSE or SFBB guidance. The relevant standard is speed of response: sightings should be logged and escalated to a contractor promptly, not left to accumulate over days.

What keeps mice away from the office?

Sealed food storage, tight waste management, gaps sealed with steel wool or copper mesh and sealant, and regular inspections are the most reliable deterrents. Ultrasonic repellers have limited evidence behind them and shouldn’t be relied on as a primary defence.

Can I refuse to work if there are rats or mice in my workplace?

Employees can raise a formal health and safety concern if they believe conditions are genuinely dangerous, and employers must respond under their duty to provide a safe workplace. Outright refusal to work is a serious step that should follow reporting and assessment, not replace it.

What should I do if there are rats or mice in my workplace?

Isolate the affected area, stop using any exposed food or equipment nearby, log the sighting, then contact a professional pest controller such as Biowise Pest Control Maintenance Services promptly. For food-handling areas, follow SFBB guidance on two-stage cleaning and consider temporary closure until the risk is assessed.

Recommended

• How to Maintain Pest-Free Workspace for Offices
• Mice in Commercial Kitchens: Ensure Your Business Passes Every Inspection – BioWise Pest Control London
• Expert Mice Control – Trust BioWise for Effective Mouse Removal
• How to Repel Mice – What Scents & Sounds Keep Mice Away – BioWise Pest Control London