Building Control in London: Full Plans vs Building Notice, Inspections, and Completion

Building Regulations apply to most building work in England. The types of work most commonly carried out by London homeowners that require Building Regulations approval include: Extensions (rear, side, loft): any new extension to a dwelling-house requires Building Regulations approval under the structural, thermal, fire, and drainage provisions (Parts A, B, C, F, H, L, and P). Permitted development or planning permission does not replace Building Regulations approval — they are separate processes. Structural alterations (load-bearing wall removal, new openings, beam installation): all structural works require approval under Part A. Loft conversions: require approval under Parts A (structural floor and roof), B (fire escape), F (ventilation), L (insulation), and typically Part P (electrical). Garage conversion to habitable space: requires approval under Parts A, B, C, F, L, and potentially Part H (drainage if new WC is added). Basement conversion: requires approval under Parts A, B (fire escape), C (damp/waterproofing), F, L, and typically Part P. Electrical works in new or extended rooms: require approval under Part P. New boiler installation or central heating replacement: requires approval under Part L and Part J (combustion appliances) — typically self-certified by a Gas Safe registered installer. New shower or bathroom with drainage: requires approval under Part H. Replacement windows and glazed doors: require approval under Part L (U-value compliance) and Part B (fire escape from bedrooms) — typically self-certified by a FENSA or CERTASS registered window installer. Works that do NOT typically require Building Regulations: like-for-like internal repairs (replacing plaster, flooring, decorating); non-structural internal works (installing fitted furniture, replacing a door within an existing opening); garden walls, fences, and gates (unless within 2 metres of a highway). When in doubt, ask the Building Control body before starting the works — they will confirm whether the proposed works are notifiable without charge.

There are two main routes for Building Regulations compliance for domestic extensions and alterations in England: Full Plans application: a Full Plans application submits detailed architectural and structural drawings, specifications, and calculations to the Building Control body before works start. The Building Control body reviews the plans and, if they comply, issues a plan check approval (a notice stating that the plans are compliant, subject to inspection during construction). The benefit of Full Plans: the contractor knows exactly what is required before they start, the plan check approval provides evidence that the design is compliant for the purpose of the sale of the property, and the homeowner has written confirmation that the design as approved will comply. The cost is slightly higher (plan check fee + inspection fees) but the certainty it provides is well worth it for any project of significant value. Full Plans is strongly recommended for: extensions (particularly structural extensions with beams); loft conversions; basement conversions; any project over £50,000. Building Notice: a Building Notice does not submit detailed drawings for pre-approval — it simply notifies the Building Control body that work is about to start, and the Building Control inspector visits during construction to check compliance. The Building Notice route is faster to initiate (no waiting for plan approval) but carries higher risk: if the inspector identifies non-compliance during the works, the contractor must stop and remediate. For a structural alteration already under construction, remediation can be very expensive. A Building Notice cannot be converted to a Full Plans application once work has started. Building Notice is appropriate for: like-for-like replacements (new boiler, new windows via competent person scheme); small domestic alterations with no structural works; works where the contractor has extensive experience and confidence in compliance. Who decides which route to use: the choice is the homeowner's (subject to any requirement in a planning condition or party wall award). In practice, for a London home extension, most experienced architects and contractors recommend the Full Plans route for the certainty it provides.

Under the Building Safety Act 2022, the Building Control market has been restructured. The two types of Building Control body that can approve domestic building work in England are: Local Authority Building Control (LABC): the Building Control department of the London Borough Council for the area where the works are taking place. LABC covers all works in the borough. LABC Building Control inspectors are council employees and are not commercially incentivised to approve works — their duty is to the public interest. Registered Building Control Approvers (formerly Approved Inspectors): private-sector Building Control companies that are registered with and regulated by the Building Safety Regulator. Examples include NHBC Building Control, Quadrant, Bureau Veritas, and many smaller firms. Under the Building Safety Act 2022, approved inspectors were required to re-register as Registered Building Control Approvers (RBCAs) by a transition deadline. RBCAs can now handle domestic building work. Key differences for a London homeowner: LABC: typically cheaper for plan check fees; slower response times (typically 5-10 working days for routine checks, longer for complex projects); the permanent official record of the works is held by the council; the Completion Certificate issued by the LABC is the standard document required by solicitors on a property sale. RBCAs: typically faster response times; may have more specialist experience in complex project types (large extensions, basements, heritage buildings); slightly higher fees; the Completion Certificate is issued by the RBCA and is equally valid for property sale purposes. Under the Building Safety Act 2022, clients are no longer able to switch between LABC and RBCA once a Full Plans application has been submitted — the choice of Building Control body must be made at the start of the project and is binding for the life of the project.

The Building Control inspection process for a London home extension typically involves the following site visit stages: Commencement notification: the contractor must notify the Building Control body that work has started (within 2 days of commencement). Foundation inspection: the inspector visits to check the foundation excavation depth and width before concrete is poured. For a London Clay foundation, this is the critical inspection — the inspector confirms that the foundation is at the correct depth and on competent bearing material. Oversite preparation inspection: the inspector checks the damp-proof membrane, insulation, and oversite preparation before the ground floor slab is poured. Damp-proof course inspection: the inspector checks the damp-proof course level and the wall cavity tie positions at first-floor level. Drainage inspection: if new drainage connections have been made (both foul and surface water), the inspector inspects and may pressure-test the drainage before backfilling. Roof structure inspection: for pitched roofs, the inspector checks the roof structure before the covering is applied; for flat roofs, the inspector checks the insulation board and the waterproofing system before the final finish is applied. Insulation and airtightness inspection: the inspector checks the insulation build-up (wall, roof, and floor) before it is concealed. Electrical and M&E inspection: where Part P electrical works have not been self-certified by a competent person, the inspector carries out an electrical inspection. Final inspection / Completion Certificate: the final Building Control inspection checks the completed works against the approved drawings and the Building Regulations. If everything is compliant, the Building Control body issues a Completion Certificate. The Completion Certificate is the document that proves the works were inspected and comply with the Building Regulations. It is required by a solicitor when the property is sold — without a Completion Certificate, the buyer's solicitor will require an indemnity insurance policy (typically £200-£500) to cover the risk of enforcement action. Obtain the Completion Certificate from the Building Control body promptly after the final inspection — it should be retained with the property's title documents.