Here's the full blog post — ready to paste straight into Site123:
Published: 1 June 2026 |
Last updated: 1 June 2026 |
By AAC Gas Engineering Team ,
If you manage a commercial premises, care home, factory, restaurant, or any business operating gas appliances across Preston, Lancashire, or the wider North West, you've probably heard the terms CP15, CP16, CP17, and CP42 — but do you know which one applies to your business and when you need it?This guide explains every commercial gas safety certificate clearly, who needs each one, how often they must be renewed, and what happens if you don't have them.
| Certificate | What It Covers | Who Needs It |
|---|---|---|
| CP15 | General commercial gas appliances and pipework | Most commercial premises |
| CP16 | Commercial boilers | Any premises with a commercial boiler |
| CP17 | Industrial and commercial pipework pressure testing | New installations or major alterations |
| CP42 | Commercial kitchen catering appliances | Any premises with a commercial kitchen |
Most businesses need more than one. A care home, for example, typically needs a CP15, a CP16, and potentially a CP42 if it has a commercial kitchen.
What it is:The CP15 is the general commercial gas safety certificate — the commercial equivalent of the domestic CP12 landlord certificate. It confirms that gas appliances, pipework, and flues across a commercial premises have been inspected and certified as safe by a Gas Safe registered engineer.
Who needs a CP15:Any commercial premises operating gas appliances that aren't covered by a more specific certificate. This includes offices, retail premises, hotels, guesthouses, factories, warehouses, care homes, schools, gyms, and any business property with gas appliances on site.
How often:Annually — once every 12 months without exception.What it covers:
What happens without one:Your commercial insurance is likely void. Environmental Health Officers and HSE inspectors can issue prohibition notices. For care homes, a missing CP15 is a direct CQC compliance failure.
What it is:The CP16 is the specific certificate for commercial boilers — issued following an annual inspection and service of a commercial boiler installation by a Gas Safe registered engineer with commercial boiler ACS qualifications.
Who needs a CP16:Any commercial or industrial premises with a commercial boiler — including care homes, hospitals, hotels, offices, factories, warehouses, schools, and any business with a central heating or hot water system served by a commercial boiler.
How often:Annually — and for high-use systems such as care homes and hospitals, every six months is best practice.What it covers:
What happens without one:Commercial boiler insurance cover is invalidated. An unserviced boiler is a carbon monoxide risk. For care homes, a missing CP16 directly affects CQC inspection outcomes. HSE can issue improvement or prohibition notices for persistent non-compliance.
Note: A CP16 is usually issued alongside a CP15 on the same visit for most commercial premises — your engineer covers the boiler specifically under the CP16 and the wider premises under the CP15.
What it is:The CP17 is issued following a tightness test and purge of commercial gas pipework — confirming that a gas installation, new pipework run, or altered gas system has been pressure tested, proven gas-tight, and safely commissioned.
Who needs a CP17:
How often:The CP17 is not an annual certificate — it is issued once following the completion of new or altered pipework work. It is a commissioning document rather than a recurring compliance certificate.What it covers:
What happens without one:Gas pipework that hasn't been properly pressure tested and certified is a safety risk. Any gas-related incident on uncertified new pipework is likely to result in insurance refusal and potential HSE enforcement. Reputable engineers will always issue a CP17 on completion of pipework work — if your contractor doesn't offer one, that's a concern.
What it is:The CP42 is the specific gas safety certificate for commercial kitchens — covering all gas-fired catering appliances, the gas interlock system, gas pipework, and ventilation within a commercial kitchen environment.
Who needs a CP42:Any premises with a commercial kitchen using gas appliances — including restaurants, hotels, pubs, takeaways, care homes, schools, hospitals, workplace canteens, event venues, and mobile catering units using LPG. There is no minimum appliance count — even a single gas appliance in a commercial kitchen requires a CP42.
How often:Annually — once every 12 months without exception.What it covers:
What happens without one:Commercial kitchen insurance is almost certainly void. Environmental Health Officers routinely check CP42 compliance during food business inspections and can issue prohibition notices closing the kitchen immediately. For care homes, a missing CP42 is a direct CQC compliance failure. Licensed premises risk licensing consequences.
Yes — most commercial premises need multiple certificates. Here are the most common combinations:
Care home: CP15 (general premises) + CP16 (boiler) + CP42 (kitchen) — all required annually. CQC inspectors check all three.
Restaurant or pub: CP15 + CP42 (kitchen) — both required annually. CP16 if there's also a commercial boiler.
Factory or warehouse: CP15 + CP16 (boiler) — both required annually. CP17 if any pipework work is being carried out.
Hotel: CP15 + CP16 (boiler) + CP42 (kitchen) — all required annually
.Office premises: CP15 + CP16 (if commercial boiler) — annually.
New build or refurbishment: CP17 on completion of all new gas pipework, then CP15/CP16/CP42 annually from that point forward.
Only a Gas Safe registered engineer with the appropriate commercial ACS qualifications for each certificate type. A domestic gas engineer — even if Gas Safe registered — is not qualified to issue any of these commercial certificates.Always verify your engineer's Gas Safe registration at gassaferegister.co.uk and confirm they hold commercial qualifications before booking.
AAC Gas are Gas Safe registered commercial and industrial gas engineers based in Higher Walton, Preston. We issue CP15, CP16, CP17, and CP42 certificates for businesses, care homes, commercial kitchens, factories, and all commercial premises across Preston, Lancashire, Manchester, Merseyside, and Cheshire.
📞 Call us: 01772 382971 — 24/7 emergency response available🌐 www.aacgas.co.ukGas Safe Registration No: 562186
