If you operate a commercial property with gas appliances, you've probably heard of CP12: the commercial gas safety certificate. If your property has a commercial kitchen, you've probably also heard of CP42. They sound similar, they're often issued by the same engineer, and people frequently confuse the two.
Here's the difference, plain.
What is a CP12?
A CP12 (sometimes called a "Commercial Gas Safety Certificate" or "CGSR") covers the general gas installation in a commercial property:
- Gas pipework
- Boilers (commercial or domestic-style)
- Water heaters
- Space heaters
- Other gas appliances not used for catering
- Flue and ventilation arrangements for those appliances
A Gas Safe registered engineer inspects the installation against the Gas Safety (Installation and Use) Regulations 1998 and issues the certificate confirming everything is safe and compliant.
CP12 is required annually for landlords of commercial premises with gas appliances. Failure to hold a current CP12 is a criminal offence under the regulations.
What is a CP42?
CP42 is the catering-specific commercial gas safety certificate. It covers everything CP12 covers plus commercial catering equipment and the specific safety systems that go with it:
- Commercial ovens, ranges, fryers, grills
- Catering gas pipework (typically larger diameter, higher pressure)
- Gas interlock systems (the safety device that cuts gas if ventilation fails)
- Ventilation canopies and extract systems specifically relating to gas appliances
- Combustion air supply
CP42 has a tighter scope because commercial catering gas is higher-risk: more appliances, higher gas loads, harder ventilation requirements, and a confined kitchen environment.
So do you need both?
It depends on what's in the property.
| Your property has | You need |
|---|---|
| Commercial gas boiler / heaters, no catering | CP12 only |
| Commercial catering only (kitchen with gas, no other gas plant) | CP42 only |
| Commercial gas boiler + commercial kitchen | Both (CP12 for the plant, CP42 for the kitchen) |
| Multiple buildings with different gas uses | One per building, of the right type |
In practice, hotels, restaurants, schools, hospitals and any other property with both heating plant and a commercial kitchen typically need both certificates.
The gas interlock requirement
One thing that catches catering operators out: the gas interlock.
Catering kitchens generate combustion products from gas appliances. If extract ventilation fails (canopy fan dies, ductwork blocks), those combustion products build up. The interlock system shuts off the gas supply automatically if ventilation isn't running. CP42 covers this.
If your kitchen doesn't have a gas interlock (or has one but it's not working), your CP42 cannot pass. This is a common reason for first-time CP42 failures.
Frequency
Both certificates are annual for commercial premises. Some specific cases require more frequent inspection (e.g. high-risk environments, after significant alteration, after a reported gas safety concern).
Some FM providers also recommend more frequent CP42 inspection for high-throughput kitchens. Twice a year is not unusual for busy restaurants, hotels and contract catering sites.
What does a CP12 / CP42 cost?
Costs vary by property size and complexity. As a rough guide for 2026:
- CP12 for a small commercial premises: £150 - £350
- CP12 for a larger property with multiple appliances: £350 - £800+
- CP42 for a small catering kitchen: £200 - £500
- CP42 for a medium-large commercial kitchen: £500 - £1,200+
- Both CP12 and CP42: typically a combined visit, total in the £400 - £1,500 range depending on complexity
Out-of-hours inspections (so the kitchen doesn't have to close) cost more.
Who can issue CP12 and CP42?
Both must be issued by a Gas Safe registered engineer with the right specific qualifications:
- CP12: requires the engineer to hold the relevant commercial gas qualifications (typically COCN1 and COCNCS or similar) under ACS.
- CP42: requires additional commercial catering gas qualifications (CCN1 + CCCN1) and ACS competence in catering-specific work.
Both engineer and company must be on the Gas Safe Register. Verify the engineer's ID card against the register before they start work.
Common compliance gaps
- CP12 in place but no CP42, despite having a commercial kitchen
- Gas interlock not tested or non-functional
- Engineer not specifically qualified for catering (issuing CP42 without the right ACS scope)
- Out-of-date certificate, no renewal scheduled
- Records held in someone's inbox, not against the property
How Avero handles CP12 and CP42
Avero coordinates commercial gas inspections through Gas Safe registered Avero FM Approved engineers. We assess what your property needs (CP12, CP42 or both) based on the appliances on site. Certificates are stored against the property in Avero FM Works. Renewals auto-schedule. The engineer's qualifications are verified before they attend.
For more on commercial gas, see the commercial gas service, or get in touch if a CP12 or CP42 is overdue.