Gas safety certificates (CP12) in London
The name CP12 comes from an old form number and has stuck, though the proper term today is just a gas safety certificate. By law, landlords in England and Wales must renew it every twelve months. A Gas Safe registered engineer from Ninja Plumbers tests each appliance, flue and length of pipework in the property. You get the certificate at the end of that visit, on the same day.
- Fully insured and Gas Safe registered
- Engineers DBS-checked
- 24/7 emergency callouts
- Price agreed before we start
- Workmanship guaranteed
Monday – Sunday, 7:00 AM – 10:00 PM · Out-of-hours emergency? Call 020 3576 5825
Get a price for gas safety certificates
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Included in the job
- Annual renewal of landlord gas safety certificates (CP12)
- Boilers, gas fires, hobs and every other gas appliance checked
- Ventilation and flue performance tested
- Your certificate issued and emailed on the same day
- Scheduling across portfolios and multiple properties for landlords and agents
- Repairs to follow up any fault the check finds
Read this before you ring
You may find you can sort some of this yourself, without calling us. We are fine with that, and would rather you knew it.
Only a Gas Safe registered engineer can do it
The law says the check must be done by an engineer registered for the particular appliance types in the property. Ask for their Gas Safe ID card; a genuine engineer will happily show it. You can also look them up on the register yourself in about thirty seconds.
It reflects the property on the day of the check
The check covers the appliances and pipework as they are installed at the time. It does not promise that nothing will go wrong later. Anything added or altered after the visit, such as a new gas hob, will need checking as well.
One failed appliance does not sink the whole certificate
An unsafe appliance is capped off or condemned and recorded, while everything else in the property can still pass. We prefer to isolate that single fault and issue the paperwork, not hold up the whole job.
Tenants need their copy within 28 days
Existing tenants must be given the current certificate no later than 28 days after the check. New tenants must have one before the day they move in. Because we email the certificate on the same day as standard, this step is hard to miss when renewal comes round.
What changes 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.
We agree the price with you before any work begins, and accept both card and cash.
Questions we often get
How long will the gas safety check take?
For a typical property, thirty to forty-five minutes, and longer if there are more appliances. You receive the certificate when the visit ends.
What if one of my appliances fails?
If an appliance is immediately dangerous, it is isolated there and then to keep everyone safe. We explain what it needs to be put right, and in most cases the certificate can still be issued for everything else.
Do homeowners need one, or only landlords?
Only landlords are legally required to have one. If you own the property and live in it, the check is optional, but a yearly visit is still a good habit, above all before winter, when your boiler does the most work.
Can several properties in a portfolio be done in one visit?
Yes. Send us the addresses and the number of appliances at each, and we can usually plan a day around a group of nearby 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.
Other plumbing jobs we do
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Emergency Plumbing
For burst pipes, serious leaks or a house with no water. The phone is answered at any hour and an engineer is sent out.
Read about Emergency Plumbing -
General Plumbing
Radiators, pipework, taps and toilets: the small jobs that keep getting put off.
Read about General Plumbing -
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.
Read about Leaking Ceiling -
Leak Repair
Leaks you can see — dripping joints, weeping valves, perished hoses, overflows running outside — isolated, repaired and checked properly afterwards.
Read about Leak Repair -
Leak Detection
Acoustic and thermal equipment to trace hidden leaks before any floor is lifted.
Read about Leak Detection -
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.
Read about Toilet Repair -
Tap Repair and Replacement
Dripping, stiff and leaking taps repaired, and tired ones swapped for new.
Read about Tap Repair and Replacement -
Pipe Repair
Burst, split, frozen and corroded pipework repaired — or replaced where patching it would be pointless.
Read about Pipe Repair -
Low Water Pressure
Weak taps and showers diagnosed by testing, not by swapping parts and hoping.
Read about Low Water Pressure -
Lead Pipe Replacement
Old lead supply pipes replaced with new, from the boundary into the house.
Read about Lead Pipe Replacement -
Commercial Plumbing
Plumbing for offices, restaurants, shops and blocks of flats, timed to fit the hours you open.
Read about Commercial Plumbing -
TMV Servicing & Testing
Thermostatic mixing valves tested, cleaned and reset, with a record for every valve, for schools, nurseries, care and business premises.
Read about TMV Servicing & Testing
Businesses use us for gas safety certificates too, among them landlords and letting agents, holiday lets and serviced apartments, hmos and shared houses and airbnb and short lets.
Advice on this topic
Looking for gas safety certificates in London?
Tell us what is wrong and where you are, and you will have the price before any work begins.