Gas safety certificates (CP12) in London
Most people still call it a CP12, going back to the old form number, but the correct name now is simply a gas safety certificate. Whatever you call it, landlords in England and Wales are legally required to renew one every twelve months. Ninja Plumbers sends a Gas Safe registered engineer to check every appliance, flue and section of pipework in the property, and the certificate is issued there and then, on the day.
- Gas Safe registered and fully insured
- DBS-checked engineers
- Emergency callout available 24/7
- Price agreed before work starts
- Workmanship guaranteed
Monday – Sunday, 7:00 AM – 10:00 PM · Out-of-hours emergency? Call 020 3576 5825
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What this includes
- Landlord gas safety certificates (CP12), annual renewal
- Checks on boilers, gas fires, hobs and any other gas appliance
- Flue performance and ventilation checks
- Certificate issued and emailed the same day
- Portfolio and multi-property scheduling for landlords and agents
- Follow-up repairs where a check identifies a fault
Worth knowing first
A little of this might mean you do not need to call us at all — we would still rather you knew it.
It has to be a Gas Safe registered engineer
Only an engineer registered for the specific appliance types in the property can legally carry out the check. Ask to see the Gas Safe ID card — every engineer should be glad to show it, and checking the register yourself takes thirty seconds.
The certificate covers what is there on the day
It is a check of the appliances and pipework as installed, not a guarantee against future faults. If something is added or changed afterwards — a new gas hob, for instance — it needs to be checked too.
A fail on one appliance does not fail the whole certificate
If one appliance is unsafe, it gets capped off or condemned and noted, and the rest of the property can still pass. We would rather isolate the one fault and get the paperwork issued than delay the whole job.
Tenants must get a copy within 28 days
The rule is 28 days from the check for an existing tenant, and before move-in day for a new one — landlords are required to hand over a copy of the current certificate either way. Emailing it out the same day, as standard, is exactly why this is not the thing that slips through the cracks at renewal time.
What affects the price
A gas safety certificate is one of the more predictable jobs we price. What moves the figure is how much gas equipment the property has, how easy it is to inspect, and whether we can get in first time.
How many appliances
A flat with a combi boiler and nothing else is the quickest check. A house with a boiler, a gas hob, a gas oven and a gas fire has more to test, and each appliance is checked and recorded separately on the certificate.
The type of appliance
Room-sealed boilers draw air from outside and are fairly quick to test. Open-flued appliances, such as older gas fires and back boilers that rely on a chimney, need flue flow and spillage tests and a ventilation check, which take longer.
Flues hidden in ceilings
Where a boiler flue runs out of sight through a ceiling void or boxing, it needs inspection hatches so the engineer can see its joints along the length. If there are none, the flue cannot be fully checked until hatches are fitted, which is extra work.
Getting in on the first attempt
Most checks happen in tenanted homes, so access depends on the tenant being in or keys being available. A wasted trip because nobody answered the door means a second visit. Confirming the appointment with the tenant a day or so beforehand saves that.
The price is agreed before any work starts. We take card and cash.
Common questions
How long does a gas safety check take?
Usually thirty to forty-five minutes for a typical property, longer with more appliances. The certificate is issued at the end of the visit.
What happens if an appliance fails?
An immediately dangerous appliance is isolated on the spot for safety. We will tell you what is needed to put it right, and the certificate can usually still be issued for the rest of the property.
Do I need one as a homeowner, not a landlord?
The legal requirement applies specifically to landlords. It is not compulsory if you own and live in the property yourself, though an annual check is still a sensible habit, especially going into winter when the boiler is working hardest.
Can you do several properties in a portfolio on the same visit?
Yes — tell us the addresses and how many appliances at each, and we can usually route a day around a cluster of properties.
Does the check cover a gas cooker my tenant owns?
The landlord’s annual check covers the gas appliances and flues you provide for the tenant. A cooker the tenant brought with them is their responsibility, not yours, although the pipework feeding it is still part of the installation. If the engineer sees something obviously unsafe with a tenant’s appliance, it will be pointed out and dealt with under the same safety rules as anything else.
Can I renew early without losing time on the current certificate?
Yes. If the check is done in the last two months before the current certificate runs out, the new one runs for a full year from the old expiry date rather than from the day of the visit, so renewing a few weeks early loses you no time. Keep both records, because the earlier one shows where that date came from.
More plumbing work we take on
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Emergency Plumbing
Burst pipes, major leaks and no water. We take calls around the clock and get an engineer moving.
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General Plumbing
Taps, toilets, radiators and pipework. The jobs that never quite get done.
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Leaking Ceiling
Water dripping or pouring through a ceiling. What to do first, then the source found and stopped — in your home or the flat above.
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Leak Repair
Leaks you can see — dripping joints, weeping valves, perished hoses, overflows running outside — isolated, repaired and checked properly afterwards.
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Leak Detection
Hidden leaks traced with acoustic and thermal equipment, before floors come up.
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Toilet Repair
Toilets that will not flush, keep running, fill slowly or leak onto the floor. Usually one worn part, replaced without needing a new toilet.
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Tap Repair and Replacement
Dripping, stiff and leaking taps repaired, and tired ones swapped for new.
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Pipe Repair
Burst, split, frozen and corroded pipework repaired — or replaced where patching it would be pointless.
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Low Water Pressure
Weak taps and showers diagnosed by testing, not by swapping parts and hoping.
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Lead Pipe Replacement
Old lead supply pipes replaced with new, from the boundary into the house.
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Commercial Plumbing
Offices, restaurants, retail and blocks of flats, worked around your opening hours.
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Related advice
Need gas safety certificates in London?
Describe the problem and give us your area, and we’ll tell you the price before anyone starts work.