Building regs for energy improvements: who signs off what

Quick answer: Nearly every energy upgrade needs building regulations sign-off, but you rarely apply yourself. Installers registered with a competent person scheme, such as FENSA for windows or Gas Safe for boilers, self-certify the work and the certificate arrives afterwards. Unregistered work means a building control application before anyone starts.

What is a competent person scheme?

It’s a government-authorised register that lets qualified installers sign off their own work as building-regs compliant, instead of you paying the council’s building control team to inspect it. The full list of authorised schemes is on gov.uk (checked August 2026).

A registered installer self-certifies the job, notifies the local authority, and the compliance certificate reaches you without building control ever visiting. Use anyone else and the legal duty to notify falls on you, with fees and an inspection to arrange before work starts.

Which energy improvements need sign-off, and who certifies what?

Here’s the checklist, with the self-certification schemes taken from the gov.uk register:

Gas Safe Register is the only scheme authorised to self-certify gas work, and anyone paid to work on gas must be on it by law. Windows carry their own quirks: replacements generally need trickle vents under the ventilation rules, which our trickle vents guide covers, and the FENSA rules explain what the certificate actually proves.

Insulation is the category people skip sign-off on most. Thermal upgrades to walls and roofs fall under Part L, and our Part L guide explains when a simple job becomes notifiable work. A one-afternoon loft top-up you do yourself isn’t normally notifiable. Reboarding a roof or insulating as part of an extension is.

Heat pumps and solar span two trades at once, which is why the microgeneration scheme list is long. The heating circuit, the electrical connection and, for panels, the roof fixing all have to comply. One firm registered with one scheme can cover the lot, and that’s the arrangement to look for on a quote rather than three subcontractors pointing at each other.

Where do MCS and HIES fit in?

Neither is on the competent person list, and that confuses people. MCS certifies installers and products for renewables, and you need an MCS installation to claim the £7,500 Boiler Upgrade Scheme grant, or £9,000 for oil and LPG-heated homes between 21 July 2026 and 31 March 2027. HIES is a consumer code covering deposits and disputes.

MCS is a quality and funding standard, not a building-regs route: the legal sign-off comes through the installer’s scheme membership, usually NAPIT or NICEIC. A decent renewables firm holds both, which is exactly what to check when vetting quotes.

What happens when work wasn’t signed off?

Nothing, for years. Then you sell, and the buyer’s conveyancer asks for the FENSA or Gas Safe certificate that doesn’t exist. The usual patches are a retrospective regularisation application to the council or an indemnity insurance policy, and both cost money at the worst possible moment.

So make it boring. Ask for the compliance certificate before you hand over final payment, and file it with the deeds. Certificates normally arrive within a few weeks of the scheme being notified; chase the scheme, not the installer, if yours doesn’t.

Can you do any of it yourself?

Some of it. A loft insulation top-up is a legitimate DIY Saturday. Draught-proofing needs no sign-off at all. Fitting your own windows is legal but means a building control application, since self-certification belongs to registered firms, and the council fee plus inspection usually eats the saving on a small job.

Notifiable electrical work follows the same logic: you can’t self-certify, so building control has to be involved before you start. And gas is the hard stop. Anyone paid to work on a gas appliance must be Gas Safe registered by law, and DIY gas work risks both your safety and the sale of your house. The jobs where DIY genuinely pays are the unnotifiable ones.

Is planning permission a separate question?

Completely separate, and clearing one system says nothing about the other. Most energy improvements are permitted development, but there are carve-outs for flats, conservation areas and listed buildings. See our guides to planning permission for solar and heat pump planning rules for where the exceptions bite.

Building regs care how the work is done; planning cares whether it should happen at all. You can fail one while sailing through the other.

FAQs

How do I check an installer is registered?

Search the scheme’s own register: FENSA, Gas Safe, NAPIT and the rest all run free online lookups. Check the specific company name on the quote, since sole traders sometimes borrow a registered firm’s branding.

Is a FENSA certificate the same as building regs approval?

It’s evidence of compliance, which is what a buyer’s solicitor wants. The installer self-certified the work rather than the council inspecting it, and the certificate proves the notification happened.

What does building control cost if my installer isn’t registered?

Fees are set by each council and vary with the job, so check your local authority’s schedule before committing. Between the fee and the inspection hassle, a scheme-registered installer is nearly always the cheaper route.