CP42 vs CP17 vs CP12: Which Gas Certificate Do You Need?
CP42, CP17 and CP12 are often searched together, but they are not the same route. The right certificate or record depends on the property use, the gas appliances, the fuel type, who controls the equipment and why the paperwork has been requested.
Start with the premises and appliances, not the code
The certificate code matters, but the first question is simpler: is the gas equipment in a restaurant kitchen, a non-domestic commercial site, or a domestic rented property? Send that context with the appliance list and any wording from your insurer, landlord, managing agent or facilities team.
CP42, CP17 and CP12 compared
These labels are often used as shorthand by insurers, landlords, agents and business owners. The wording alone is not enough to confirm the correct route. The site use, appliance type and engineer competence still need to match the actual gas work.
| Certificate or record | Commonly linked to | Typical customer | Details to send |
|---|---|---|---|
| CP42 | Commercial catering gas appliances and kitchen equipment. | Restaurants, cafes, takeaways, pubs, hotels, dark kitchens, bakeries and catering operators. | Appliance list, kitchen access, fuel type, trading hours, ventilation notes and the requested deadline. |
| CP17 | Non-domestic commercial gas installation, pipework, boiler, water heater, plant or premises records. | Commercial landlords, facilities teams, offices, shops, warehouses, managed premises and business occupiers. | Site use, appliance or plant details, gas meter or plant-room access, landlord or tenant responsibility and certificate wording. |
| CP12 | Domestic landlord gas safety checks for rented homes. | Landlords, letting agents, property managers and homeowners arranging domestic rental paperwork. | Rental address, domestic appliances, tenant access, landlord or agent contact and renewal or move-in deadline. |
| Not sure | Mixed-use buildings, HMO properties, commercial units below flats, landlord-controlled plant or unclear insurer wording. | Managing agents, commercial landlords, property managers and business tenants. | Send the postcode, full site use, equipment list, fuel type, access notes and exact wording from the person requesting the certificate. |
Which gas certificate route is more likely?
Use these examples as a starting point. The final route should still be checked against the actual appliances, fuel and site responsibility.
Choose CP42 if the issue is a commercial kitchen
If the request is for a restaurant, cafe, takeaway, pub kitchen, hotel kitchen or catering appliance, CP42 or a commercial catering gas certificate is usually the phrase customers are looking for.
Choose CP17 if the site is commercial but not mainly catering
If the request relates to an office boiler, commercial unit, shop, warehouse, plant room, landlord-controlled gas installation or managed premises, CP17 may be the more relevant route.
Choose CP12 if it is a domestic rented home
If the property is a rented house, flat or domestic dwelling with domestic gas appliances, the enquiry is usually closer to a landlord gas safety certificate route.
When CP42, CP17 and CP12 can be confused
London properties are often mixed-use. A restaurant may sit below flats, a landlord may control a commercial plant room, or a managing agent may need paperwork for several units with different equipment. In these situations, one label may not cover every part of the building.
Do not assume a domestic landlord certificate covers commercial equipment, and do not assume a catering certificate covers every non-domestic gas installation on the site. Send the full site picture so the route can be checked before booking.
Useful wording to include
Tell us who asked for the certificate, what wording they used, who controls the appliances, whether the gas equipment is domestic or commercial, and whether the building has more than one occupier.
Send the site detailsWhat to send before booking
A clear enquiry helps avoid the wrong route being discussed. Send the details once and include the reason the paperwork is needed.
- Full address, postcode, trading name or property reference.
- Property use: restaurant, cafe, takeaway, shop, office, warehouse, commercial landlord unit, HMO, flat or rented home.
- Gas appliance list, including catering equipment, boilers, water heaters, heaters, domestic appliances or LPG equipment.
- Fuel type: natural gas, LPG or mixed fuel.
- Certificate wording requested: CP42, CP17, CP12, commercial gas certificate, catering gas certificate or landlord gas safety certificate.
- Who requested it: insurer, landlord, letting agent, managing agent, facilities team, buyer, tenant or local authority contact.
- Access details, opening hours, key-holder, tenant contact, parking or building management requirements.
- Deadline and reason, such as insurance renewal, annual compliance, lease completion, handover, opening or tenancy start date.
Why competence matters more than the code
Gas Safe Register explains that engineers have categories of work they are qualified to carry out, and HSE guidance for employers says gas fittings in workplaces such as shops, restaurants, schools and hospitals must be worked on by a Gas Safe registered engineer who is qualified for the work. That is why the appliance type and premises use matter.
Send the certificate wording and site details
Use the form to send the postcode, business or property type, certificate wording, appliance list, fuel type, access notes and deadline. We will confirm the suitable route by phone or email.
CP42, CP17 and CP12 FAQs
What is the difference between CP42, CP17 and CP12?
CP42 is commonly linked to commercial catering gas equipment, CP17 to non-domestic commercial gas installations or premises records, and CP12 to domestic landlord gas safety checks.
Do restaurants usually need CP42 or CP17?
Restaurants, cafes and takeaways commonly ask for CP42 when the request is about commercial catering appliances. CP17 may be relevant where the request relates to wider non-domestic gas installation, boiler, plant or premises paperwork.
Is CP12 suitable for a commercial property?
CP12 is normally associated with domestic rented homes. Commercial premises, catering sites, offices, shops and plant rooms may need a different commercial gas record depending on the equipment and site use.
What if my insurer or landlord only says gas certificate?
Send the exact wording, site use, appliance list, fuel type and deadline. That helps confirm whether the request is closer to CP42, CP17, CP12 or another commercial gas route.
Can one visit cover more than one certificate route?
Sometimes multiple records can be discussed for the same address, but it depends on the appliances, engineer competence, access and whether domestic and commercial areas are separate. Send the full site details before booking.
What is the fastest way to get the right certificate?
Send the postcode, business or property type, appliance list, fuel type, access notes, certificate wording and deadline. If the certificate is urgent for opening, trading, insurance or handover, call as well.
Still unsure which gas certificate you need?
Send the site details and certificate wording. We will help confirm the next suitable route by phone or email before the appointment is agreed.