What Building Control Is
Building Control is the process of checking that building work complies with the Building Regulations — the legal minimum standards that construction in England and Wales must meet. Its purpose is safety and quality: making sure a building is structurally sound, safe in a fire, energy efficient, properly drained and fit to live in.
Whenever you build an extension, convert a loft, carry out structural alterations or undertake a major refurbishment, the work is almost certainly notifiable to Building Control. An inspector reviews the design and visits the site at key stages, and — if everything complies — issues a completion certificate at the end.
The Building Regulations are split into “Approved Documents”, each covering a different aspect of construction. You do not need to read them yourself — that is your designer's and contractor's job — but it helps to understand what they cover.
What the Building Regulations Cover
The Regulations set standards across a wide range of construction issues. The main areas relevant to typical domestic projects are:
- Structure — foundations, loadings, beams and walls must be safe and stable
- Fire safety — escape routes, fire-resisting construction, alarms and protected areas
- Ventilation — adequate airflow to control condensation and damp
- Insulation and energy efficiency — thermal performance, U-values and heat loss
- Drainage and waste — foul and surface water drainage, and waterproofing
- Electrical safety — fixed wiring installed and tested to recognised standards
- Accessibility — level access, usable spaces and suitable facilities
- Sound insulation — between dwellings and within larger conversions
- Glazing and protection from falling — safety glass, guarding and stairs
These standards apply regardless of whether your project needs planning permission. A loft conversion under permitted development still has to meet every relevant Regulation — fire escape, structure, insulation and so on — and Building Control is how that is verified.
Building Control vs Planning Permission
This is the distinction homeowners get wrong most often. They are two separate approvals, run by different teams, answering different questions.
Planning permission is about appearance and land use — whether a development is acceptable in its location, how big it is, how it looks, and its impact on neighbours and the surrounding area. It is decided by the council's planning department.
Building Control is about construction safety and standards — whether the thing is actually built correctly, to the Building Regulations. It does not care how the building looks; it cares whether the foundations are adequate, the structure is sound and the fire escape works.
A project can need both, just one, or — for some permitted-development work — Building Control without planning permission. Passing one does not satisfy the other. For a fuller comparison, read our guide on planning permission vs building regulations, and if you are unsure whether your project needs consent at all, see do I need planning permission for an extension.
Who Carries Out Building Control
For a typical domestic project you can choose one of two routes:
Local Authority Building Control (LABC)
The Building Control department of your local council. They check plans, carry out site inspections and issue the completion certificate. This is the traditional route and works well for most extensions, loft conversions and refurbishments.
A private Registered Building Control Approver
A private-sector provider — the role known until recently as an Approved Inspector. They perform the same function as the council: plan checks, inspections and certification. Many contractors and warranty providers have established relationships with private firms.
The Building Safety Act 2022 reformed how Building Control operates. Individual building inspectors must now be registered with the Building Safety Regulator and demonstrate competence for the class of work they oversee. The former “Approved Inspector” firms became “Registered Building Control Approvers” as part of the same changes.
For defined “higher-risk buildings” — broadly, taller residential blocks — Building Control is no longer a free choice between LABC and a private approver: the Building Safety Regulator (part of the Health and Safety Executive) is the building control authority. For ordinary domestic work — extensions, lofts, single houses — this does not change your day-to-day route, but it is worth knowing the framework has tightened.
Full Plans vs Building Notice
There are two ways to make a Building Control application, and the right one depends on the complexity of your project.
Full Plans application
You submit detailed drawings and specifications before work starts, and Building Control checks them for compliance and issues a decision. It suits extensions, loft conversions, structural alterations and anything complex — because you get written confirmation that your design complies before a brick is laid. Mortgage lenders and warranty providers generally prefer this route.
Building Notice
A simpler route with no detailed plans submitted in advance — you give notice and work is inspected as it proceeds. It can be quicker to start and suits small, straightforward jobs. The downside is you carry the risk: if something does not comply, you may have to undo and redo work because there were no approved plans to rely on. It cannot be used for work near a public sewer or for some commercial uses.
For most extensions and loft conversions, the Full Plans route is the safer choice. Getting your design checked and approved before work starts removes the risk of building something that has to be undone — and it gives lenders and warranty providers the paper trail they expect.
What Gets Inspected
Building Control does not visit once at the end — it inspects at defined stages, many of which are “hold points” where work must be checked before it is covered up. A competent contractor books each inspection at the right moment.
Foundations and excavation
The inspector checks the trench depth, ground conditions and reinforcement before any concrete is poured. This is the most critical early hold point — once concrete is in, it cannot be reviewed.
Oversite and damp-proof course (DPC)
The ground floor build-up, damp-proof membrane and DPC level are checked to confirm the structure is protected from rising damp and ground moisture.
Drainage
Drainage runs, falls and connections are inspected before they are covered over, and an air or water test is carried out to confirm the pipework is sound and leak-free.
Structural steel and beams
Steel beams, padstones and structural openings are checked against the structural engineer’s calculations to confirm loads are properly supported.
Floor and roof structure
Joists, trusses, restraint straps and the overall roof structure are inspected to confirm they are built to the approved design.
Insulation and thermal envelope
Wall, floor and roof insulation is checked before it is concealed, to confirm the building meets the required energy-efficiency and U-value standards.
Final completion inspection
Once everything is finished, a final inspection confirms the completed work complies in full. If it passes, a completion certificate is issued.
The exact stages vary with the project, but the principle is constant: anything that will be hidden — foundations, drains, insulation, structure — is inspected before it is concealed. Skipping these checks is what leads to work having to be opened up later.
The Completion Certificate — Why It Matters
When the final inspection passes, Building Control issues a completion certificate. It is the single most important document your project produces, because it is the formal proof that the work complies with the Building Regulations.
Its real value appears later. When you sell or remortgage, your conveyancing solicitor and the buyer's solicitor will ask for the completion certificate for any extension, loft conversion or structural work. Mortgage lenders require it too. If you cannot produce one, the transaction can stall while the issue is investigated — and in some cases buyers walk away.
No certificate is not a minor administrative gap; it is a defect in the property's paperwork that follows the building for the rest of its life. Always make sure the certificate is obtained and stored safely with your property documents.
What Happens With Unauthorised Work or No Certificate
Work carried out without the required Building Control involvement — or never signed off — creates a set of problems that usually surface at the worst possible moment:
The cleanest position is always to have had the work inspected and certified at the time. Retrospective routes exist, but they are slower, more uncertain and sometimes require finished work to be exposed for inspection. Indemnity insurance manages the legal risk of enforcement — it does not make the work safe or compliant.
RCB's Approach to Building Control
On every RCB project, Building Control is built into how we work rather than treated as an afterthought. We design and build to current Building Regulations as standard, prepare the structural drawings and calculations a Full Plans application needs, and coordinate every inspection at the correct stage so nothing gets covered before it is checked.
At the end of the project we make sure your completion certificate is obtained and handed over — so when you eventually come to sell or remortgage, the paperwork is complete and your property's records are sound.
Why Clients Trust RCB With Compliance
- We design and build to current Building Regulations as standard
- We coordinate every Building Control inspection at the right stage
- We work with both Local Authority Building Control and Approved Inspectors
- We hand over your completion certificate as part of project close-out
- Structural calculations and drawings prepared by qualified engineers
- Fully documented build records for sale, remortgage and warranty purposes
Planning an Extension or Loft Conversion?
RCB handles the full process — design, Building Control, structural calculations, inspections and certification — so your project is compliant from foundations to completion. If you are also weighing up quotes, our quote comparison service can help you spot which builders have properly accounted for Building Control fees and structural costs.