London Property Renovation Compliance Checklist: Before and After You Build

Renovating a London property without the right consents can be expensive to reverse and almost impossible to hide when you come to sell. This checklist covers the key compliance steps for most domestic renovations — from loft conversions to full rewires — structured as a before-and-after guide.

Before Work Starts

Planning Permission

• Check if your work falls within permitted development rights (PD). Extensions, loft conversions and outbuildings often do, but conservation areas, listed buildings and flats are frequently excluded.
• Apply for a Lawful Development Certificate if relying on PD — this protects you at sale.
• Submit a full planning application for anything outside PD scope. Allow 8 weeks for a decision.

Building Regulations

• Determine whether your project is notifiable under Building Regulations. Structural work, extensions, loft conversions, new drainage connections and electrical rewires all require Building Regs approval.
• Choose between a Full Plans application (submitted before work, best for complex projects) or a Building Notice (faster but riskier for complex work).
• Engage a structural engineer early if removing load-bearing walls or altering the roof structure.

Party Wall Act

• If work affects a shared wall, boundary wall or excavation within 3–6 metres of a neighbour's foundation, serve a Party Wall Notice at least two months before starting.
• Appoint a Party Wall Surveyor if a neighbour dissents.

Specialist Consents

• Gas Safety: all gas work must be carried out by a Gas Safe registered engineer. There is no self-certification route for homeowners.
• Electrical: all notifiable electrical work (consumer unit replacement, new circuits, outdoor wiring) must be carried out by a Part P registered contractor or notified to building control.
• Drainage: connecting to a public sewer or building within 3 metres of a public sewer requires Thames Water / sewerage authority consent under Section 106 of the Water Industry Act.

During the Renovation

• Keep a site diary and photograph progress, particularly before closing up walls and floors — this evidence is invaluable if any dispute arises later.
• Book building control inspections at the correct stages (foundations, damp proof course, structural frame, pre-plaster). Missing a stage inspection can require opening up finished work.
• Do not change the specification without notifying your building control officer — substituting materials can invalidate the approval.

After Work Is Complete

Certificates You Must Obtain

• Building Regulations Completion Certificate — issued by the local authority or your approved inspector. Without this, you cannot demonstrate the work complies, and conveyancers will flag it.
• Electrical Installation Certificate (EIC) — for any new electrical circuits or consumer unit replacement.
• Gas Safe Building Regulations Compliance Certificate — for any new boiler installation or gas pipework.
• FENSA or CERTASS certificate — for replacement windows and doors (these are self-certifying schemes).

Insurance and Mortgage

• Notify your buildings insurer of any structural changes before the work begins and again when it completes — failure to do so can void your policy.
• If remortgaging after a renovation, the lender's surveyor will inspect and may require sight of completion certificates.

Land Registry

• If your extension or outbuilding alters the boundary of the registered title, update the Land Registry title plan.