Building work generates paperwork — and some of that paperwork is legally required. Missing a certificate can cause real problems when you come to sell, insure, or mortgage your home. This guide walks you through the key certificates and inspections for common types of building work in England and Wales, so you know exactly what to expect and what to chase your builder for.
Building Control Sign-Off
Building Regulations approval is required for most structural or significant building work — extensions, loft conversions, removing load-bearing walls, new drainage, and anything that affects fire safety or energy efficiency. Your builder or architect typically submits a Building Notice or Full Plans application to your local council (or an Approved Inspector). Inspections happen at key stages: foundations, damp-proof course, drainage, and structural framing. Once the work is finished and passes final inspection, you receive a Completion Certificate. This is the single most important document from any major project — mortgage lenders and solicitors will ask for it when you sell.
Gas Safe Certificate
It is illegal for anyone who is not Gas Safe registered to work on gas appliances in the UK. After installing or servicing a boiler, cooker, gas fire, or any gas appliance, the engineer must provide a Gas Safe certificate (officially called a Building Regulations Compliance Certificate for new installations, or a Landlord Gas Safety Record for rental properties). The certificate confirms the appliance is safe, correctly installed, and meets current regulations.
Electrical Certificates
Part P of the Building Regulations covers electrical safety in dwellings. Notifiable electrical work — new circuits, consumer unit replacements, and any electrical work in bathrooms or kitchens — must be either done by a registered electrician (NICEIC, NAPIT, ELECSA, or similar) or inspected by Building Control. There are two main certificate types: an Electrical Installation Certificate (EIC) for new installations and major alterations, and a Minor Electrical Installation Works Certificate (MEIWC) for smaller jobs like adding a socket to an existing circuit.
Energy Performance Certificate (EPC)
An EPC rates your property's energy efficiency from A (most efficient) to G (least efficient). You need one whenever you sell or let a property, and it's valid for 10 years. While you don't need a new EPC just because you've had building work done, significant improvements — a new boiler, insulation, double glazing — will improve your rating and can add value to your home. Your builder won't provide this; you commission it separately from an accredited energy assessor.
Planning Permission
Planning permission controls what you can build, where, and how big. Many common home improvements fall under Permitted Development rights, meaning you don't need to apply — but the rules are specific and depend on your property type, location, and any previous extensions. If your home is in a conservation area, is a listed building, or you've already used your permitted development allowance, you'll almost certainly need planning permission.
Party Wall Agreement
The Party Wall etc. Act 1996 applies when you're doing building work on or near a shared wall, boundary, or excavating within 3 or 6 metres of a neighbouring building (depending on depth). You must serve written notice on your neighbours at least two months before work starts (one month for a party fence wall or boundary). If your neighbour agrees in writing, no surveyor is needed. If they dissent — or simply don't respond within 14 days — both sides must appoint a surveyor to produce a Party Wall Award.
FENSA & CERTASS (Window and Door Replacements)
Replacement windows and doors must comply with Building Regulations for thermal performance and safety. Rather than getting Building Control to inspect every window job, most installers use a self-certification scheme — FENSA or CERTASS are the two main ones. When a registered installer replaces your windows, they notify Building Control on your behalf and you receive a certificate confirming compliance. This certificate is essential when selling your home.