Party Wall & Planning Permission

Do I need planning permission?

Many extensions and conversions in Buckinghamshire fall under Permitted Development — the national rules that let homeowners build without a full planning application, provided strict size and design limits are met. A single-storey rear extension up to 6 m on a detached house, hip-to-gable loft conversions and most internal works are common examples.

However, permitted development does not apply in conservation areas, AONBs (the Chilterns covers a large slice of the county) or to listed properties. Front extensions and anything beyond 4 m in height typically need a full application.

We almost always advise applying for a Lawful Development Certificate even when works fall under permitted development. It's a definitive ruling, takes 6–8 weeks, and is invaluable on resale.

Householder vs full planning

A Householder Application covers most extensions, loft and garage conversions, and is decided within 8 weeks. A Full Application is required for new dwellings, subdivisions, or works affecting listed buildings (where you'll also need Listed Building Consent).

Buckinghamshire Council publishes a local plan and design guide; in villages like Penn, Chalfont St Giles or Great Missenden the conservation officer carries real weight. We engage with planning officers before submission as a matter of course.

The Party Wall etc. Act 1996

If your works affect a shared wall, build within 3 metres of a neighbour's foundations (6 metres in some cases), or build a new wall up to the boundary, the Act applies. You must serve formal notice on adjoining owners.

• Line of Junction notice — for a new wall on or up to the boundary. One month's notice.
• Party Structure notice — for cutting into, raising, or rebuilding a shared wall. Two months' notice.
• Adjacent Excavation notice — for excavating near a neighbour's foundations. One month's notice.

If a neighbour consents in writing within 14 days, no further process is needed. If they dissent (or don't respond), each party appoints a surveyor — or both agree on a single "Agreed Surveyor" — who produces a Party Wall Award setting out the works, timings and protections. Surveyor costs are usually borne by the building owner.

Building Control & approved inspectors

Separate from planning, Building Regulations cover the technical performance of the building: structure, fire, insulation, drainage, ventilation, glazing. Approval is via the local council or a private Approved Inspector. Inspections happen at defined stages — foundations, DPC, drainage, pre-plaster, completion.

A reasonable timeline

• Weeks 1–4 — design, measured survey, planning pre-app where relevant.
• Weeks 4–12 — planning application validated and determined (8 weeks for householder).
• Weeks 8–16 — building regs package, structural calcs, tender pricing.
• Weeks 12–18 — party-wall notices served, awards agreed.
• Week 20 onwards — site start.