Rear Extensions in Lambeth

The single-story rear extension is the foundation of modern family living in the London Borough of Lambeth. However, expanding the footprint of a Victorian terrace in Herne Hill or a 1930s semi in Streatham brings applicants face-to-face with the council's rigid interpretations of scale and subordination. Lambeth planners actively combat the 'over-development' of garden space.

Whether navigating Permitted Development (PD) rights or fighting for Full Planning Permission, depth and garden retention are the absolute determining metrics for rear extensions.

The Crucial Metrics of Rear Expansion

Lambeth planning rules dictate the maximum viable footprint based on mathematical ratios, not applicant desires:

• Depth Limits: Under standard PD, rear extensions are capped at 3 metres for attached houses and 4 metres for detached. The Prior Approval scheme (Larger Home Extensions) theoretically allows up to 6 or 8 metres, but in dense Lambeth postcodes, neighbors routinely object. Once an objection is lodged, Lambeth planners apply the exact same daylight and amenity tests as a full planning application, frequently refusing these deeper extensions.
• The 50% Garden Rule: Lambeth rigidly enforces the rule that no more than 50% of the original curtilage (excluding the footprint of the original house) can be covered by buildings. This calculation includes all existing sheds, bike stores, and previous additions. If your proposed rear extension pushes boundary coverage to 51%, it will fail validation.
• Subordination and Eaves Height: Planners require that an extension visually bows to the original property. For flat-roof rear extensions under PD, the maximum height is 3 metres. If the extension sits within 2 metres of a boundary line, the eaves height can absolutely not exceed 3 metres, fundamentally restricting internal ceiling heights on properties with raised ground floors.

Official Lambeth Council Resources

Before committing to any major architectural project, we strongly advise cross-referencing your ambition directly with the local authority. The following links provide direct access to Lambeth Council's live planning portals and heritage registries:

• Lambeth Planning & Building Control Portal
• Search Live Lambeth Planning Applications
• Lambeth Heritage, Conservation Areas & Article 4 Directions

How We Can Help

If you are considering a major refurbishment, extension or basement in Lambeth, our in-house architectural and construction teams are highly experienced with the specific constraints and policies of this council. Do not leave your planning application to chance—our Planning & Permissions and Architecture services are explicitly designed to handle strict London authorities from initial conceptual design through to final, legal consent.

Once permission is secured, our Refurbishment & Interiors division carefully manages the execution, guaranteeing the design integrity is maintained throughout the build phase.

*Published in the Hampstead Renovations Planning Guide Collection — delivering expert design and build strategies for London's most heavily guarded conservation boroughs.*