Gas Safety

Why gas safety matters

Carbon monoxide (CO) is an invisible, odourless, and tasteless gas produced when gas appliances don't burn fuel properly. It kills around 40 people in the UK each year and sends over 4,000 to hospital.

The tragic deaths could be prevented with three simple measures: proper installation, annual safety checks, and carbon monoxide alarms.

Employers also have duties under the Health and Safety at Work Act 1974 to ensure gas appliances in workplaces are safe and properly maintained.

Who needs to worry about gas safety?

If you have any control over premises with gas appliances, gas safety is your responsibility. This includes:

• Landlords — responsible for all gas appliances, fittings, and flues in rental properties and HMOs
• Employers — responsible for gas safety in workplaces, including staff accommodation
• Property managers — managing properties on behalf of landlords
• Commercial property owners — responsible for gas appliances in commercial premises
• Hospitality operators — restaurants, cafés, hotels with gas cooking or heating
• Care home operators — responsible for residential care premises with gas installations
• Building managers — responsible for communal gas systems in blocks of flats

Gas safety by sector

Different sectors face different gas safety challenges. Select your sector for tailored guidance:

The key legislation

Gas Safety (Installation and Use) Regulations 1998 (GSIUR)

The main gas safety law in Great Britain. Key requirements include:

• Only Gas Safe registered engineers can legally work on gas appliances
• Landlords must ensure annual safety checks are completed
• A record of each check (CP12) must be kept for 2 years
• Landlords must provide a copy of the CP12 to existing tenants within 28 days and to new tenants before they move in
• Gas appliances and flues must be maintained in a safe condition
• Adequate ventilation must be provided for gas appliances

Health and Safety at Work etc. Act 1974

Employers must ensure, so far as reasonably practicable, the health, safety, and welfare of employees and others affected by their work. This includes:

• Ensuring gas appliances in workplaces are safe
• Arranging competent maintenance and checks
• Providing adequate information, instruction, and training
• Having emergency procedures for gas leaks and CO incidents

Gas Safe registration

The Gas Safe Register is the official list of gas engineers who are qualified to work legally and safely on gas appliances in the UK.

Why it matters

It's illegal for anyone to carry out gas work unless they're on the Gas Safe Register. Unregistered work:

• Puts lives at risk from carbon monoxide poisoning and gas explosions
• Invalidates home insurance
• Can result in prosecution of both the fitter and the person who hired them
• Often costs more to rectify than it would have cost to do properly

How to check registration

Always verify before hiring:

1. Ask to see their Gas Safe Register ID card — all registered engineers carry one
2. Check the card shows the types of work they're qualified to do — appliances, pipework, LPG, etc.
3. Verify online — visit gasaferegister.co.uk/find-an-engineer or call 0800 408 5500
4. Don't rely on business cards alone — anyone can print these

Landlord gas safety certificates (CP12)

The landlord gas safety record — commonly called a CP12 — is the certificate issued after an annual gas safety check.

What the check covers

A Gas Safe registered engineer must check:

• All gas appliances — boilers, cookers, fires, heaters
• Gas pipework and fittings — for leaks and condition
• Flues and chimneys — for blockages and proper ventilation
• Safety devices — that thermostats, flame failure devices work correctly
• Ventilation — adequate air supply for safe combustion
• Carbon monoxide detectors — operation and positioning (best practice, not always legally required for CP12)

Landlord obligations

Under GSIUR Regulation 36:

• Annual checks are mandatory — must be within 12 months of installation or last check
• Keep records for 2 years minimum — you may need to produce them to HSE or in disputes
• Provide to existing tenants within 28 days — of the check being completed
• Provide to new tenants before they move in — or on the day they move in at the latest
• Arrange prompt repairs — if the engineer identifies any issues

Common CP12 issues

• "At Risk" (AR) appliances — the engineer may disconnect or cap off appliances that are unsafe
• "Immediately Dangerous" (ID) appliances — these must be disconnected immediately and not used until repaired
• Ventilation problems — blocked or inadequate vents can cause CO buildup
• Flue defects — cracked or blocked flues can allow CO to escape into rooms

If the engineer identifies problems, they must tell you immediately. For ID appliances, they'll disconnect the gas supply and attach a warning notice. Never use the appliance until it's repaired and certified safe.

Carbon monoxide alarms

Carbon monoxide alarms are your last line of defence against CO poisoning.

Legal requirements

England (since 1 October 2015):

• Private landlords must install a CO alarm in any room with a solid fuel burning appliance (e.g., coal fire, wood burner)
• Social landlords must install CO alarms in rooms with any gas appliance under the Social Housing (Regulation) Act 2023 (from April 2023)

Scotland:

• Mandatory CO alarms in rooms with any carbon-fuelled appliance (gas, oil, solid fuel) since February 2022

Wales:

• Mandatory CO alarms in rooms with any fixed combustion appliance (gas, oil, solid fuel) since December 2022

Northern Ireland:

• No specific legal requirement for CO alarms yet, but highly recommended

Choosing the right alarm

• British Standard BS EN 50291 — look for this mark
• Audible alarm — loud enough to wake you at night (85dB minimum)
• Power source — mains powered with battery backup is best; battery-only is acceptable but needs regular checks
• Lifespan — most alarms last 5-10 years; check the manufacturer's date
• Sealed battery units — good for rental properties (less tampering, longer life)

Where to install

• In every room with a gas appliance (or other fuel-burning appliance)
• 1-3 metres from the appliance (horizontally)
• At head height when seated/lying down (not on the ceiling like smoke alarms)
• Away from windows, doors, and extractor fans that might disperse CO before detection

Testing and maintenance

• Test alarms monthly — press the test button to ensure the alarm sounds
• Replace batteries — when low battery warning sounds (unless sealed unit)
• Replace the alarm — after 5-10 years or as per manufacturer's instructions
• Keep a log — especially in rental properties, record tests and replacements

Annual safety checks

Gas appliances must be checked for safety every 12 months by a Gas Safe registered engineer.

When to book

• Before your current certificate expires — don't leave it to the last day
• Allow time for repairs — if issues are found, you need time to fix them before the deadline
• During tenancy changeover — convenient time for landlords (but not required)
• At the same time each year — easier to remember and plan

What happens during a check

The Gas Safe engineer will:

1. Examine all gas appliances — visual inspection for damage, corrosion, leaks
2. Test flues — check for blockages, proper ventilation, CO spillage
3. Check ventilation — adequate air supply to appliances
4. Test safety devices — flame failure devices, thermostats, pressure relief valves
5. Inspect pipework — for leaks, condition, proper installation
6. Use gas detectors — to check for leaks and CO presence
7. Record findings — on the CP12 certificate
8. Advise on issues — and classify any defects (NCS, AR, ID)

Cost

Typical costs for an annual gas safety check:

• Single appliance (e.g., boiler only) — £60-80
• Standard property (boiler + cooker) — £80-120
• HMO or multiple appliances — £100-180+
• Urgent/emergency call-outs — £150-300+

Prices vary by region and property complexity. Get quotes from several Gas Safe registered engineers.

After the check

• Keep the certificate safe — you'll need it for at least 2 years
• Give copies to tenants — within 28 days (or before they move in)
• Act on any issues immediately — especially AR or ID classifications
• Set a reminder for next year — don't let it lapse

Recognising gas safety problems

Know the warning signs of gas leaks and carbon monoxide:

Signs of a gas leak

• Smell of gas — a strong, distinctive smell (like rotten eggs)
• Hissing sound — near gas appliances or pipes
• Dead plants — in the area of a leak
• Pilot lights blow out repeatedly

If you suspect a gas leak:

1. Turn off the gas supply at the meter (if safe to do so)
2. Open doors and windows
3. Don't smoke, use switches, or create sparks
4. Call the National Gas Emergency Service: 0800 111 999
5. Don't return until told it's safe

Signs of carbon monoxide poisoning

• Headaches and dizziness
• Nausea and vomiting
• Tiredness and confusion
• Stomach pain
• Shortness of breath
• Difficulty breathing

Symptoms often similar to flu but without a temperature. Get worse in enclosed spaces and improve in fresh air.

If you suspect CO poisoning:

1. Get outside into fresh air immediately
2. Call 999 and ask for ambulance
3. Don't go back inside until premises checked by Gas Safe engineer
4. See a doctor — CO poisoning can have delayed effects

Signs of unsafe gas appliances

• Yellow or orange flames — should be crisp and blue (except decorative fuel-effect fires)
• Sooty marks on walls — near appliances or on appliances themselves
• Pilot lights blow out frequently
• Increased condensation — on windows in the room with the appliance
• Stale, stuffy air

If you notice any of these signs, turn off the appliance and call a Gas Safe registered engineer immediately.

Gas safety review schedule

Gas safety maintenance is ongoing. Here's what you should be doing regularly:

Common questions

Real enforcement examples

Related sectors

Gas safety requirements affect multiple sectors differently:

Related content

Explore related health and safety topics:

• Fire Safety → — Fire risk assessments, responsible person duties, Fire Safety Order compliance
• Electrical Safety → — EICR requirements, PAT testing, electrical installation safety
• Landlord Responsibilities → — Complete guide to landlord health and safety duties

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Disclaimer: This guidance is for general information only and does not constitute legal advice. Gas safety law is complex and your specific circumstances may require professional advice. Always use Gas Safe registered engineers for gas work. For definitive guidance, consult the Gas Safety (Installation and Use) Regulations 1998, HSE guidance, or seek professional advice.