What is the Building Regulations fee for an extension in London?

Building Regulations fees in London depend on the borough and project type. For a single-storey extension (Full Plans): plan charge typically £200–£400 + inspection charge £300–£600 = total £500–£1,000. For a loft conversion (Full Plans): total £800–£1,500. Fees differ between LABC and Approved Inspectors — Approved Inspectors are often slightly cheaper and faster for straightforward projects. Builderr obtains Building Regulations fee quotes as part of the project cost plan.

Can I use a Building Notice for a loft conversion in London?

Technically yes, but it is not recommended. A loft conversion involves significant structural works (ridge beam, purlins, floor joists), fire safety requirements (mains-wired smoke alarms, fire doors), thermal performance (insulation to Part L), and in some cases acoustic requirements — all of which benefit from a pre-approved specification. A Building Notice for a loft conversion puts the builder and homeowner at risk of mid-build compliance requirements with no pre-agreed specification as reference.

What is an Approved Inspector and is it better than local authority building control in London?

An Approved Inspector is a private building control body authorised by the Construction Industry Council (CIC) to provide building control services as an alternative to LABC. Major Approved Inspectors in London include NHBC Building Control, SLD Building Control, Premier Guarantee, and AIBC. Advantages of Approved Inspectors: often faster plan checking (3–4 weeks vs 5–6 weeks for some LABC), single point of contact throughout the project, and competitive fees. Disadvantages: LABC has statutory enforcement powers that Approved Inspectors do not — if there is a dispute, only LABC can take enforcement action.

What happens if I don't get Building Regulations approval for an extension in London?

Unlike planning permission (which has a 4-year enforcement limitation for dwellings), there is no time limit for Building Regulations enforcement — the LPA can serve a notice requiring remediation at any time if non-compliant work is discovered. On a property sale, the absence of a building control completion certificate triggers a solicitor's enquiry. Regularisation applications are available to retrospectively approve completed work, but they require opening up works for inspection and may require expensive remediation to achieve compliance.

Building Notice vs Full Plans Approval London 2025 | Building Control

Should I Use a Building Notice or Full Plans Approval in London?

A Building Notice is quicker to submit (no drawings required upfront) but gives less certainty — the inspector checks compliance as work progresses and can require changes mid-build. Full Plans Approval involves submitting detailed drawings for approval before work starts, and gives a legally enforceable approved specification. For any significant extension or loft conversion in London, Full Plans Approval is recommended for cost and programme certainty.

Building Notice: what it is, how it works and when to use it

A Building Notice is a simplified Building Regulations notification procedure under Regulation 12(2) of the Building Regulations 2010. You submit a Building Notice form and fee to your local authority building control (LABC) or an Approved Inspector (private building control body). No drawings are required with the submission — you notify the building control body that work is starting in 48 hours, and an inspector visits during construction to check compliance with Building Regulations. The Building Notice route is intended for straightforward, low-risk works where an experienced builder and site manager can manage compliance without a pre-approved specification. In practice, it is most appropriate for: minor works (replacement of a like-for-like boiler, roof repair, replacement windows under 25m²); small single-storey extensions where the builder has an established working relationship with the building control body; and internal alterations where no structural changes are involved. The risks of the Building Notice route are: the building control inspector can require changes to work in progress if non-compliance is identified — expensive if this triggers structural rework; there is no approved specification against which to hold a contractor accountable for non-compliance; and on completion, the building control body issues an informal completion certificate rather than a Final Certificate (LABC) or Completion Certificate (Approved Inspector) based on approved drawings — which can cause issues with solicitors on sale. Approved Inspectors (private building control bodies: NHBC Building Control, SLD Building Control, Premier Guarantee, etc.) also offer a Building Notice equivalent service.

Full Plans Approval: what it is, process, cost and why it is recommended for major works

Full Plans Approval (formally: Approval under Regulation 14 of the Building Regulations 2010) requires submission of detailed technical drawings and a specification to building control before work starts. The building control body reviews the plans and issues a Decision Notice: either Approval (the plans comply with Building Regulations), Conditional Approval (approval subject to specified amendments), or Rejection (non-compliant — with reasons, and an opportunity to resubmit). Once Full Plans Approval is granted, the approved drawings are the legally enforceable specification for the project. The inspector's role during construction is to verify that work is built in accordance with the approved drawings, rather than making compliance judgements on the fly. Full Plans Approval is strongly recommended for: extensions over one storey; loft conversions (structural, fire, thermal, acoustic compliance all required); basement conversions (structural waterproofing, drainage, ventilation all require approved drawings); and any project involving structural alterations (new openings, steelwork, underpinning). The Full Plans Approval process typically takes 5–6 weeks for a householder application. Cost: LABC fees for a single-storey rear extension with Full Plans Approval range from £600–£1,200 in London boroughs (plan charge + inspection charge); for a loft conversion, £900–£1,600; for a double-storey extension, £1,200–£2,000. Approved Inspector fees are broadly comparable. On completion, Full Plans Approval projects receive a Final Certificate or Completion Certificate — the definitive building control sign-off that is required by conveyancing solicitors on sale and by mortgage lenders. Note: from October 2023, the Building Safety Act 2022 introduced significant changes to building control for Higher Risk Buildings (buildings over 18m or 7 storeys containing flats) — a new Building Safety Regulator (BSR) is the building control authority for these buildings, not LABC or Approved Inspectors.