Gas Safety Certificate (CP12) — London
Gas Safety Certificates London (CP12)
Annual gas safety inspections and CP12 Landlord Gas Safety Records for boilers, cookers, gas fires and flues across every London borough. Carried out by Gas Safe registered engineers, issued same day, with copies sent to tenants and letting agents automatically. Book once and we track your renewal date so you are never caught with an expired certificate.
£60–£110
Typical London CP12 inspection cost (2025)
12 months
Legal renewal interval for rented properties
£6,000
Maximum fine for a landlord without a valid certificate
2 years
Minimum period records must be retained
On this page
What a Gas Safety Certificate actually is
A Gas Safety Certificate — almost always called a CP12, though its correct name is the Landlord Gas Safety Record — is the written result of an annual inspection of every gas appliance, flue and piece of pipework a landlord has provided at a property. A Gas Safe registered engineer checks each appliance for correct operating pressure, safe ventilation, effective flue operation and the absence of gas leaks, then records a pass or fail against every item. If a fault makes an appliance dangerous, the engineer must disconnect it there and then, whatever the tenant or landlord would prefer, and note the disconnection on the record.
The legal duty sits with the landlord under the Gas Safety (Installation and Use) Regulations 1998. It applies to every rented property in England and Wales that contains a gas appliance supplied by the landlord, whether that is a combi boiler, a gas hob, a gas fire or a gas-fired water heater. The regulations set three concrete obligations: the inspection must be repeated at intervals of no more than 12 months, a copy of the current record must be given to existing tenants within 28 days of the check, and a copy must be given to any new tenant before they move in. Failing any one of these is a criminal offence, prosecuted through the Health and Safety Executive, and is treated separately from any civil liability if a tenant is later injured by a gas fault.
London adds practical pressure to this simple-sounding rule. A landlord letting six flats across three agents in three boroughs is juggling six different renewal dates, and it is common for a certificate to lapse quietly between tenancies, particularly on a property that has just been re-let and where the previous check was carried out for the outgoing tenant. HMOs compound this further, since a single boiler serving multiple households still needs one certificate covering the whole installation, and selective licensing schemes in boroughs such as Newham, Croydon and Waltham Forest specifically ask to see the current CP12 as part of a licence renewal or a council inspection. Engineers working across London routinely find installations that technically passed a check years ago but have since had appliances added, moved or swapped without a corresponding gas safety re-inspection.
Scope of work
What is checked during a gas safety inspection
A CP12 inspection covers every gas appliance and the pipework and flue serving it, not just the boiler. The engineer works through a fixed checklist so nothing is missed and every result is recorded against the specific appliance.
Boiler and gas fire operation
The engineer checks burner pressure or heat input against the manufacturer data plate, confirms the safety devices (flame supervision, overheat cut-outs) operate correctly, and inspects the casing and seals for damage that could allow flue gases to escape into the room.
Flue performance and termination
Every flue is checked for a physical spillage or flue-flow test to confirm combustion products are safely carried outside. The external termination point is inspected to ensure it has the correct clearance from windows, doors and boundaries and has not been blocked or obstructed.
Ventilation adequacy
Air vents and grilles serving the appliance are checked to make sure they have not been painted over, blocked by furniture, or removed during redecoration. Inadequate ventilation starves the appliance of air and is one of the most common reasons a check fails.
Gas tightness and pipework
A tightness test is carried out on the installation pipework to confirm there are no leaks. Visible pipework is inspected for corrosion, incorrect jointing and unsafe routing, including any pipework buried in walls or floors without proper protection.
Appliance stability and installation location
Each appliance is confirmed to be securely fixed and correctly located — for example, that no gas fire has been fitted in a bedroom or bathroom without the specific ventilation and interlock arrangements those rooms require under the regulations.
Cookers and hobs
Where the landlord has supplied a gas cooker or hob, it is included in the same inspection: burner operation, flame picture, stability of the appliance and the condition of the flexible connector are all checked and recorded.
When to act
Who legally needs a gas safety certificate, and common failures found
Unlike a repair, a gas safety check is not something you wait for a symptom to prompt — it is a fixed annual legal duty. This section explains who the duty applies to and what inspections most often turn up in London properties.
Any landlord letting a property with gas appliances
The duty applies the moment a tenancy exists and the landlord has supplied the appliance, boiler or gas pipework — assured shorthold tenancies, lodger arrangements where the landlord provides appliances, and company lets are all covered. Owner-occupiers have no equivalent legal duty, though an annual service is still sound practice.
Managing agents acting on a landlord's behalf
Where an agent manages the property, the landlord's legal duty does not transfer to the agent unless a specific written agreement says so. Many disputes after HSE investigations centre on exactly this point, so landlords using an agent should confirm in writing who books the annual check.
HMO and multi-let landlords
Houses in multiple occupation need the same annual check, and where a single boiler serves several separately let rooms, one certificate can cover the shared appliance provided every appliance and flue in the property is included and clearly identified on the record.
Missing or overdue records at change of tenancy
A very common finding is a certificate that expired between one tenancy ending and the next starting, because no one booked a renewal during the void period. The safest habit is to renew on a fixed calendar date rather than tying it to the tenancy start date.
Corroded flexible connectors on cookers
Flexible gas connectors behind free-standing cookers are one of the most frequent failure points found on inspection, especially where a cooker has been moved for cleaning and reconnected incorrectly, or where the connector has simply reached the end of its service life.
Blocked or painted-over ventilation grilles
Tenants and decorators regularly paint over, cover, or remove air vents without realising they are safety-critical. This is consistently one of the top reasons an appliance is found to be operating with inadequate ventilation during the annual check.
How it works
How the annual gas safety check works, step by step
The inspection itself typically takes 30 to 60 minutes for a single boiler and slightly longer with additional appliances. The process is the same whether it is a routine renewal or the first check on a newly acquired property.
01
Booking and access
You give us the property address, the appliances present and, where relevant, the tenant's contact details so we can arrange access directly. We confirm a same-week appointment and send a reminder the day before.
02
Identification and appliance list
On arrival the engineer confirms Gas Safe ID, then lists every gas appliance in the property that falls under the landlord's responsibility, including any the tenant may have added, which are noted as outside the certificate scope.
03
Tightness and pipework test
A gas tightness test is carried out on the whole installation before individual appliances are tested, so any leak is identified and isolated before proceeding further.
04
Appliance-by-appliance testing
Each appliance is tested in turn — burner pressure or heat input, flue performance, ventilation and safety device operation — with the pass or fail result recorded against that specific appliance.
05
Any faults addressed immediately
If an appliance is found to be immediately dangerous it is disconnected and labelled on the spot, whatever else that means for heating or cooking that day. At risk faults are explained clearly along with the options and cost to fix them.
06
Certificate issued and distributed
The CP12 is completed and issued the same day. A copy is emailed to you and, on request, sent directly to the tenant or agent, keeping you inside the 28-day distribution deadline without having to manage the paperwork yourself.
Buyer guide
How to book a legitimate gas safety check without overpaying
Gas safety inspections are cheap enough, and common enough, that they attract a fair amount of undercutting and corner-cutting. These checks help landlords tell a properly registered engineer doing a full job from someone issuing a certificate without doing the work behind it.
Check the Gas Safe registration number
Every legitimate engineer carries a Gas Safe ID card with a licence number and a list of the specific appliance categories they are qualified to work on. You can verify any engineer or business on the Gas Safe Register website before booking, and it takes under a minute.
Understand what a fail actually means
A fail on the CP12 is recorded against a specific appliance and a specific reason — for example, inadequate ventilation or a flue fault — not the property as a whole. Ask the engineer to explain the fault in plain terms and what specifically needs to happen to pass, rather than accepting a vague verdict.
Be wary of unnecessary "at risk" upselling
A responsible engineer distinguishes clearly between "immediately dangerous" (disconnected on the spot), "at risk" (needs remedying but can stay on) and advisory notes. If every visit somehow turns into an urgent, expensive replacement recommendation, get a second opinion before authorising work.
Combine visits to save money
A gas safety check and an annual boiler service cover overlapping ground and are often carried out together for a modest additional cost rather than two separate call-out fees. Landlords with several properties in one area can also usually negotiate a portfolio rate by batching appointments on the same day.
Keep records for at least two years, ideally longer
The regulations require records to be kept for a minimum of two years, but keeping the full history for as long as you own the property protects you if a dispute or HSE enquiry ever looks back further than the current certificate.
Red flags to walk away from
A certificate offered without the engineer actually attending the property, a price dramatically below the local market rate, an engineer unwilling to show ID, or a certificate missing the individual appliance details are all signs the paperwork will not hold up under scrutiny.
2025 pricing
Gas safety certificate costs in London (2025)
Prices depend mainly on the number of appliances at the property and whether the visit is combined with a boiler service. The figures below are typical for a single London property in 2025 and include the certificate.
| Job | Detail | Price range (2025) |
|---|---|---|
| Single appliance (boiler only) | CP12 for one gas appliance | £60 – £85 |
| Boiler plus hob or cooker | CP12 covering two appliances | £75 – £100 |
| Full property (boiler, hob, fire) | CP12 covering three or more appliances | £90 – £130 |
| Combined service and CP12 | Annual boiler service plus certificate | £120 – £180 |
| HMO / shared boiler property | CP12 covering a shared appliance serving multiple lets | £100 – £160 |
| Portfolio rate (per property) | Multiple properties booked on one visit | £55 – £90 per property |
Where a fault is found and needs remedial work, that work is always quoted and agreed separately before it is carried out — it is never bundled silently into the inspection price. Landlords with several London properties can usually save on call-out costs by scheduling all annual checks in the same week.
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Gas Safety Certificates London (CP12) — get a clear quote
Tell us about the property and the job. A qualified engineer confirms the scope, agrees a price before work starts, and issues the correct certificate on completion. All 33 London boroughs covered.
Common questions
Gas Safety Certificates London (CP12): frequently asked
What is a CP12 and is it a legal requirement?
CP12 is the common name for the Landlord Gas Safety Record produced after an annual gas safety check. It is a legal requirement under the Gas Safety (Installation and Use) Regulations 1998 for any landlord who supplies gas appliances in a rented property. The check must be carried out by a Gas Safe registered engineer, repeated at least every 12 months, and the current record given to the tenant within 28 days of the check and to any new tenant before their tenancy begins. There is no exemption for short lets, lodgers where the landlord provides appliances, or company tenancies.
How often does a gas safety certificate need renewing?
At least once every 12 months, calculated from the date of the previous check rather than a fixed calendar date, though many landlords choose a fixed date to make renewals easier to track across several properties. You can have the check done up to two months before the expiry date without losing any time from the original 12-month cycle, which is a useful window for booking around tenant availability.
What happens if my gas safety certificate expires?
Letting a property without a valid, in-date gas safety certificate is a criminal offence under the 1998 Regulations, enforced by the Health and Safety Executive, with fines that can reach £6,000 per breach and, in serious cases, imprisonment. Beyond the legal risk, an expired certificate is also commonly checked by local authorities during licensing inspections and can complicate insurance claims if a gas-related incident occurs while the certificate was lapsed.
Who is legally responsible for arranging the gas safety check — landlord or agent?
The legal duty always rests with the landlord, even where a managing agent handles the property day to day, unless there is a specific written management agreement transferring that responsibility. It is worth confirming in writing exactly who is responsible for booking the annual check, since "the agent normally does it" is not a legal defence if no certificate is ever produced.
Does a gas safety certificate cover boiler servicing as well?
No — a CP12 confirms the appliance is operating safely, but it is not the same as a full annual service, which typically includes cleaning components, checking the heat exchanger and topping up system pressure to maintain efficiency and manufacturer warranty conditions. Many landlords combine the two in a single visit for convenience and a modest cost saving, but they are legally and practically distinct.
What is the difference between "immediately dangerous" and "at risk" on a gas safety record?
An appliance classed as immediately dangerous presents a risk serious enough that the engineer must disconnect it during the visit, regardless of the tenant's wishes, and cannot leave it connected under any circumstances. An "at risk" classification means a defect exists that should be remedied but does not require immediate disconnection, so the appliance can usually remain in use while a repair is arranged. Both classifications are recorded on the certificate along with the reason.
Do I need a gas safety certificate for a property I live in myself?
No — the legal duty under the 1998 Regulations applies specifically to rented properties where a landlord supplies the appliances. Owner-occupiers have no equivalent statutory obligation, though an annual service is still strongly recommended for safety and to maintain manufacturer warranties on the boiler.
Can I get a gas safety certificate the same day I book it?
Yes, in most cases. The inspection itself takes between 30 minutes and an hour depending on the number of appliances, and provided no dangerous fault requires further work, the certificate is issued on the same visit. We can also email a copy directly to you, your tenant or your managing agent immediately afterwards, keeping you comfortably within the 28-day distribution deadline.