Understanding Building Control and When You Need Sign-Off

What Does Building Control Actually Do?

Building control exists to make sure construction work meets the Building Regulations — the minimum standards for health, safety, energy efficiency, and accessibility in buildings. Whether you're extending a house, converting a loft, or replacing a boiler, certain types of work need building control approval and inspection.

For builders, understanding what triggers a building control application — and what doesn't — saves time, avoids delays, and keeps you on the right side of the law.

Which Works Need Building Regulations Approval?

Works That Almost Always Need Approval

| Work Type | Why It Needs Approval | |----------|----------------------| | Extensions (any size) | Structural, thermal, drainage, fire safety | | Loft conversions | Structural alterations, fire escape, stairs, insulation | | Garage conversions | Change of use, thermal performance, ventilation | | Structural alterations (removing walls, steels, openings) | Structural integrity | | New or replacement roof (structural changes or re-covering) | Structure, thermal performance | | Underpinning | Structural stability | | New drainage or changes to drainage | Building Regs Part H | | Electrical work (notifiable under Part P) | Safety — see below | | Replacement windows and doors | Thermal performance (unless FENSA/CERTASS registered) | | New heating system or boiler | Safety, efficiency (unless Gas Safe registered for gas) | | Installation of a solid fuel appliance (wood burner) | Fire safety, ventilation, flue requirements | | Changes to a building's use | Fire, access, thermal performance |

Works That Don't Usually Need Approval

• Like-for-like repairs — replacing a broken roof tile with the same tile, repointing brickwork
• Cosmetic work — plastering, painting, new kitchen units (without moving plumbing)
• Garden walls and fences (unless retaining walls)
• Paths and patios (unless affecting drainage to the public sewer)
• Detached buildings under 15m² with no sleeping accommodation
• Detached buildings 15–30m² that are at least 1m from any boundary and non-combustible (or 2m for combustible materials)
• Porches under 30m², not within 2m of a highway, with ground-level floor

The Grey Areas

Some jobs sit in a grey area. If you're unsure, use the Pre-App Checker to assess whether your project is likely to need building regulations approval before you commit to the work.

Replacing a consumer unit — notifiable under Part P, but if done by a registered electrician on a competent person scheme, they self-certify. If not, you need Building Control.

Replacing windows — if your installer is registered with FENSA or CERTASS, they self-certify. If not, you need Building Control.

Boiler replacement — Gas Safe registered engineers self-certify gas work. Oil and solid fuel have equivalent schemes (OFTEC, HETAS). Unregistered installers need Building Control.

Local Authority vs Approved Inspectors

You have two choices for building control in England and Wales:

Local Authority Building Control (LABC)

• The council's own building control department
• You submit a full plans application or a building notice
• They inspect the work at key stages
• They issue the completion certificate

Approved Inspectors (Private)

• Private companies authorised to carry out the building control function
• Often quicker turnaround and more flexible on inspection scheduling
• They issue an initial notice to the local authority and a final certificate on completion
• Typically used on larger projects or where the builder has an ongoing relationship with an inspector

Key difference: If an approved inspector goes out of business during your project, the file reverts to the local authority. This has happened — make sure your inspector is established.

Full Plans vs Building Notice

| Approach | How It Works | Best For | |---------|-------------|---------| | Full plans application | Submit detailed drawings and specifications before work starts. Building control checks and approves (or requests amendments). | Extensions, conversions, structural work — anything complex | | Building notice | Notify building control that you're about to start work. No pre-approval — they inspect as you go. | Simpler works like drain connections, replacement windows by non-registered installers |

Important: A building notice does not give you any up-front approval. If the inspector finds non-compliant work, you'll have to open it up and redo it at your own cost. For anything involving structural steels, drainage runs, or foundation design, always go the full plans route.

Stages of Inspection

When you submit a building control application, they'll want to inspect at certain stages. You must give notice (usually 24–48 hours) before covering up work at each stage.

Typical Inspection Stages

| Stage | What They Check | |------|----------------| | Commencement | Site set-up, confirmation of what's being built | | Foundation excavation | Depth, width, ground conditions, any trees nearby | | Foundation concrete | Concrete poured to correct level, steel reinforcement (if required) | | DPC/DPM | Damp-proof course and membrane correctly installed and lapped | | Oversite | Ground preparation, insulation, radon barrier (if required) | | Drainage | Falls, bedding, joints, air test | | Structural frame/steels | Steel sizes match calculations, padstones, bearings correct | | Pre-plaster | Insulation fitted, electrical and plumbing first fix, fire stopping | | Final inspection | Everything complete — finishes, safety glazing, ventilation, testing certificates |

Do not cover up or proceed past any stage without the inspector's sign-off. If you concrete over foundations without an inspection, you may be asked to dig them up.

The Completion Certificate

When all inspections are passed and the work is finished, building control issues a completion certificate (local authority) or a final certificate (approved inspector).

Why It Matters

• You need it to sell the property — conveyancing solicitors check for completion certificates. Missing certificates cause delays, price reductions, or collapsed sales
• Mortgage lenders require it — a lender may refuse to mortgage a property with unapproved work
• Insurance — some insurers won't cover structural work without a completion certificate
• It's a legal requirement — the Building Act 1984 requires completion certificates for all notifiable work

What If You Don't Have One?

If work was done without approval (or approval was obtained but the certificate never issued):

• Within 12 months: Contact building control and request an inspection. They may still issue a certificate if the work is compliant
• After 12 months: You'll need a regularisation application. Building control will inspect (which may mean opening up completed work) and charge a fee (typically 150% of the normal application fee)
• Alternatively: Obtain indemnity insurance — this doesn't certify the work but gives the buyer/lender financial protection. Most solicitors accept this for minor works

Exempt Works Under the Building Regulations

Some work is explicitly exempt under Schedule 2 of the Building Regulations 2010:

• Detached single-storey buildings under 15m² containing no sleeping accommodation
• Detached single-storey buildings 15–30m² (with conditions — see above)
• Nuclear shelters under 30m²
• Greenhouses and agricultural buildings (subject to conditions)
• Temporary buildings (up to 28 days)
• Mobile homes and caravans (covered by separate legislation)
• Ancillary buildings within the curtilage of a dwelling used for purposes incidental to the enjoyment of the dwelling (subject to conditions)

Competent Person Schemes

For certain types of work, you can avoid a separate building control application by using a competent person scheme. The installer self-certifies their work and the scheme notifies building control on their behalf.

| Trade | Scheme Examples | Work Covered | |------|----------------|-------------| | Electricians | NICEIC, NAPIT, ELECSA | Part P electrical work | | Window installers | FENSA, CERTASS | Replacement windows and doors | | Gas engineers | Gas Safe Register | Gas appliance installation | | Oil engineers | OFTEC | Oil appliance installation | | Solid fuel engineers | HETAS | Solid fuel appliance installation | | Plumbers | APHC, SNIPEF | Unvented hot water systems, bathrooms | | Cavity wall insulation | CIGA members | Cavity wall insulation |

If you're using a subcontractor for any of these trades, check they're registered and that they will provide the self-certification. Otherwise, you'll need to arrange building control yourself.

Use the CDM Checker alongside your building control application to make sure you're meeting your CDM duties for larger or more complex projects.

Practical Tips for Builders

• Notify early — submit your application or building notice before you start. Retrospective applications cost more and create problems
• Build a relationship with your inspector — they're not the enemy. A good building control officer can help you solve problems on site
• Keep records — file all inspection reports, test certificates (drainage, electrical, gas), and structural calculations. You'll need them for the completion certificate
• Don't skip inspections — it's tempting to push on, but unchecked work is unapproved work
• Ask questions — if you're not sure whether something needs approval, phone building control and ask. They'd rather advise you upfront than enforce afterwards