We get calls from landlords every week who've let their CP12 lapse — sometimes by a few days, sometimes by months. Without exception, they didn't realise the consequences until something went wrong. This guide is for anyone who rents out a property in Hertfordshire and wants to understand exactly what the law requires.
What is a CP12, and why does it matter?
A CP12 — officially called a Landlord Gas Safety Record — is issued by a Gas Safe registered engineer after they've checked every gas appliance, flue and fitting in your rental property. It's not a recommendation. It's a legal requirement under the Gas Safety (Installation and Use) Regulations 1998.
The certificate must be renewed every 12 months, without exception. There's no grace period. If your tenants moved in on 1 March and your CP12 expired on 28 February, you are non-compliant — even if the inspection was otherwise fine.
What does the inspection actually cover?
We check everything connected to the gas supply:
- Boiler — combustion quality, flue integrity, safety controls, heat exchanger condition
- Gas hob or cooker — burner condition, ignition, stability bracket
- Gas fires and decorative flames — ventilation, heat output, CO emissions
- Visible pipework — leaks, corrosion, incorrect fittings
- Flues and ventilation — that combustion gases are properly expelled
Every appliance is graded as Safe, At Risk, or Immediately Dangerous. An 'Immediately Dangerous' appliance must be disconnected before we leave — tenants cannot use it. Most landlords are surprised how often we find borderline or failing appliances in properties that have never had an issue reported.
Your legal obligations — the full list
As a landlord, you are legally required to:
- Have all gas appliances and flues inspected every 12 months by a Gas Safe registered engineer
- Give existing tenants a copy within 28 days of the inspection date
- Give new tenants a copy before they move in — not within a few days, before
- Keep records of every certificate for at least two years
This applies to residential tenancies including ASTs, HMOs and short-lets if you're a private landlord. Social housing has slightly different rules.
What happens if you don't have a valid certificate?
The consequences are worse than most landlords expect:
- Fines up to £6,000 per offence from the Health and Safety Executive
- Criminal prosecution — a landlord in Hertfordshire was prosecuted in 2023 for a three-year lapse
- Landlord insurance may be void — many policies exclude gas incidents without a valid CP12
- Section 21 notices can be invalidated — courts have repeatedly ruled that a missing gas safety record means you cannot legally evict using a no-fault notice
Beyond the legal consequences: carbon monoxide poisoning kills around 40 people in the UK every year. Most of those deaths involve faulty appliances in rented accommodation.
HMOs and portfolio landlords
If you own an HMO in Watford, St Albans or anywhere else in Hertfordshire, check your licence conditions — many councils require the CP12 to be lodged with them directly, not just held on file.
For landlords with multiple properties: we offer reduced rates for portfolio clients and can coordinate annual visits across several addresses to minimise disruption and admin.
How long does it take and what does it cost?
A standard inspection — boiler and gas hob — takes 45–60 minutes. Properties with multiple gas appliances (gas fires, additional hobs, old back boilers) take longer.
We charge £120 + VAT for a CP12 on a single property. Combined with a boiler service, the rate is £170 + VAT — which most landlords find better value since the service checks often flag issues before they turn into failed inspections.
Same-day certificates issued. We cover all of Hertfordshire — call 0208 092 1359 to book.
What if the boiler fails?
If something fails during the inspection, we'll explain the issue and your options clearly. Minor faults — a worn electrode, a sensor reading out of range — are often repairable on the day. More significant failures require a follow-up visit or replacement. We never condemn appliances unnecessarily; if something is borderline, we'll tell you that too.
The most important thing: don't put off booking the inspection because you're worried the boiler might fail. A failed inspection is far less damaging than a lapsed CP12 and a tenant who knows about it.
Book your CP12
We issue same-day certificates across Hertfordshire — Watford, St Albans, Hemel Hempstead, Stevenage, Barnet, Edgware, Enfield, Rickmansworth and all surrounding areas. Gas Safe registered (No. 936121).
Get in touch or call 0208 092 1359. We'll confirm your appointment within the hour.