Erection of a second floor rear extension approved in Westminster

Erection of a Second Floor Rear Extension Approved in Westminster

Project Overview

The client wished to add a second-floor rear extension to their Victorian mid‑terrace home in Westminster. The objective was to create a new bedroom and shower room upstairs, whilst ensuring minimal impact on neighbouring properties and contributing to conservation area character.

Planning Policy Context

In Westminster, rear extensions at second‑floor level are controlled by Local Plan Part 1, Part 2 and relevant conservation area guidelines. We:

• Reviewed permitted development rights and identified that prior approval was not applicable due to restricted conservation status
• Analysed relevant London Plan policies (D4, HC1) and Westminster’s UDP/City Plan
• Prepared a Design and Access Statement referencing national planning policy (NPPF paragraphs 126, 130) and local design guidance

Pre‑Application Engagement

We advised the client to undertake pre‑application consultations with Westminster City Council conservation officers.

• This helped clarify parameters around height, projection and materials
• Feedback led to adjustments in window proportions and brickwork detailing to better match the rear elevation

Erection of a Second Floor Rear Extension Design & Impact

Design Response and Materials

Key design interventions included:

• Lightweight steel frame forming the extension to reduce load on the existing structure
• Matching London stock brick to maintain consistency with the host building
• Slimline black metal window frames to reflect contemporary detailing without overpowering the heritage context

Site Constraints and Structural Considerations

• The existing building had limited roof access and tight party walls
• Structural engineers designed internal steel beams and reinforced joists to allow for a flat roof and floor area
• We coordinated closely with engineers to ensure insulation, drainage and fire safety details met Building Regulations

Neighbouring Amenity and Overlooking

To address privacy and outlook issues we:

• Limiting the rear projection to less than 3m, as required
• Ensured windows were aligned with existing openings and fitted with clear glass only where overlooking was not an issue
• Submitted daylight and overshadowing assessments to Westminster’s standards to demonstrate negligible impact

Erection of a Second Floor Rear Extension -  Application & Consent

Submission Package

Our planning application included:

1. Site location plan
2. Proposed and existing floor plans and section drawings
3. Design and Access Statement with policy justification
4. Structural feasibility statement from an engineer
5. Daylight and privacy report
6. Materials schedule showing brick, roofing and window samples

Consultation and Amendments

The case officer consulted immediate neighbours. We responded to a minor representation by adjusting boundary detailing and updating a condition plan, which resulted in the neighbour withdrawing their objection.

Permission Granted

Permission was granted in 10 weeks. Conditions included:

• Use of specified matching materials
• Details of roof waterproofing and drainage
• Restriction that the extension must remain ancillary to the main dwelling (not to become separate flat)

Erection of a Second Floor Rear Extension  -  Project Outcome

Quality Living Space Added

The new second floor rear extension added approximately 15m² of well‑lit living space. The new bedroom suite includes shower room and improved access, enhancing the home’s long‑term functionality and resale value.

Conservation and Design Integration

By utilising sympathetic materials, scale and detailing, the extension sits softly within the existing roofscape, preserving the Victorian terrace rhythm and character.
The lightweight construction also minimised structural load and reduced disruption during construction.

Policy‑Led Approach Delivered

Our thorough approach - grounded in local and national policy, pre‑application consultation, structural coordination and governed design - resulted in a quick and smooth approval process for our clients.

Conclusion

This erection of a second floor rear extension approved in Westminster illustrates how careful policy analysis, precise design influence, and early stakeholder engagement can deliver a high‑quality additional living space in a challenging central London context.

If you’d like support with a similar project - or need advice on extensions in conservation areas - please get in touch. We can assist with pre‑application advice, full planning submissions, design options, and construction coordination.