What building work requires Building Regulations approval?▾
Most building work in the UK requires Building Regulations approval, including: new builds, extensions, loft conversions, garage conversions, structural alterations, rewiring, new heating systems, replacement windows (unless by FENSA installer), and changes of use. Minor work like painting, tiling, and replacing kitchen units is usually exempt. When in doubt, contact your local Building Control office.
What is the difference between planning permission and Building Regulations?▾
Planning permission controls what you build, where you build it, and how it looks (handled by your local planning authority). Building Regulations control how you build it — ensuring structural safety, fire safety, energy efficiency, and accessibility (handled by your local authority Building Control team or a Registered Building Control Approver). You may need one, both, or neither depending on the work. They are completely separate legal processes.
How much does a Building Control application cost?▾
Building Control fees vary by local authority and project size. Typical fees for a domestic extension are £200-£600. For a new dwelling, fees range from £500-£1,500. Fees usually have two parts: a plan charge (paid on submission) and an inspection charge (paid on first inspection). Registered Building Control Approvers (private sector) may offer competitive packages. VAT applies to private sector fees but not local authority fees.
What happens if I do not get Building Regulations approval?▾
Building without approval is a criminal offence. Your local authority can require you to alter or remove non-compliant work, even after completion. They can serve an enforcement notice up to 12 months after completion (no time limit for dangerous work). When selling your property, solicitors will ask for completion certificates and missing certificates can delay or prevent sales. Retrospective regularisation is possible but expensive.
What is a Building Regulations completion certificate?▾
A completion certificate is issued by your local authority Building Control team, or a final certificate by your Registered Building Control Approver, when they are satisfied that the work complies with Building Regulations. It is an important legal document that you should keep safely. You will need it when selling the property. If you never received one for past work, you can apply for a regularisation certificate, though this involves inspections and fees.
Do I need Building Regulations for a loft conversion?▾
Yes, almost all loft conversions require Building Regulations approval. Key areas include structural adequacy of the new floor, fire safety (including a protected escape route with fire doors), staircase design, insulation (Part L), head height, ventilation, and electrical safety. Even a simple room-in-roof conversion with no external alterations needs approval.
What U-values are required for Building Regulations?▾
Under Approved Document L Volume 1 (2021 edition, in force 15 June 2022), the notional new dwelling specification is: walls 0.18 W/m²K, roof 0.13 W/m²K, floors 0.13 W/m²K, windows 1.2 W/m²K. For extensions and work to existing buildings the standards are less stringent: walls 0.28, roof 0.16, floor 0.22, and a replacement window must achieve 1.4 W/m²K (1.6 is the worst value permitted, not a target). These figures are the interim uplift on the way to the Future Homes Standard, which was published on 24 March 2026 and comes into force for non-higher-risk building work on 24 March 2027, with a 12-month transition. Higher-risk buildings follow six months later.
Are Building Regulations different in Scotland?▾
Yes. Scotland has its own Building Standards system governed by the Building (Scotland) Act 2003. Instead of Approved Documents, Scotland uses sections 1-7 of the Technical Handbooks. While the principles are similar, specific requirements differ — for example, Scotland requires CO alarms in all homes and has different energy standards. A building warrant is required before starting work.
What is a Registered Building Control Approver?▾
A Registered Building Control Approver (RBCA) is a private-sector alternative to your local authority Building Control team. RBCAs are registered with the Building Safety Regulator, which sits within the Health and Safety Executive, and the individual inspectors they employ must themselves be Registered Building Inspectors. The role replaced the old "Approved Inspector" on 6 April 2024 under the Building Safety Act 2022; the previous CICAIR register closed on 1 October 2024. RBCAs perform the same plan checking and site inspections but may offer faster response times and a more flexible service. Note that RBCAs cannot act on higher-risk buildings, where the Building Safety Regulator is the sole building control authority.
Do I need Building Regulations for replacing windows?▾
Yes, replacement windows must comply with Building Regulations (Part L for energy efficiency, Part K for safety glazing, Part F for ventilation, and Part Q for security). Note that ventilation is Part F, not "Part N" — Part N was withdrawn in 2013 and its safety-glazing content was folded into Part K. The easiest route is to use a FENSA-registered installer, who will self-certify the work and notify Building Control on your behalf. If you use a non-registered installer, you must apply to Building Control directly, which adds cost and time.