The project at a glance

Project type

New build flats feasibility study Lewisham | Small residential development | Site intensification

Location

Westdown Road, Lewisham, London

Brief

Feasibility study for the demolition of an unsafe existing house and redevelopment of the site to create a replacement residential building containing flats, together with a separate self-contained dwelling within the rear garden.

Development potential tested

A replacement main building with 5 flats, together with a single-storey 2-bedroom garden dwelling, creating 6 residential units in total and 5 additional homes beyond the original single dwelling.

Architectural services provided

Feasibility study, pre-application design proposals, planning submission and Building Regulations considerations, and preparation of proposals to request pre-application advice from Lewisham Council.

Feasibility study for a structurally failed house on a planning-sensitive deep plot

GOAStudio was appointed to test a replacement development strategy for a structurally failed Victorian house on a deep residential plot in Lewisham.

The study considered whether the site could support a new main building with flats together with a separate rear garden dwelling, while maintaining a credible planning position on a site affected by a non-designated heritage issue.

The existing house was in a severe state of disrepair and structurally unfeasible to repair.

The rear garden extended to approximately 30 metres, creating scope for a more intensive site strategy than a straightforward replacement dwelling.

Site context

The site is on the southern side of Westdown Road and includes a front garden and a rear garden of approximately 30 metres in depth. It sits within a predominantly residential area and is within walking distance of Catford and Catford Bridge stations. The site is not in a conservation area, is not listed, and is not adjacent to a listed building.

The planning position was relatively open in those respects, but the site was still sensitive.

The existing house was considered to have architectural merit and was treated as a non-designated heritage asset. Any redevelopment strategy therefore had to address not only density and layout, but also the planning case for demolition and replacement.

Development option tested

The feasibility study explored a redevelopment strategy consisting of:

• a three-storey replacement main building
• and a self-contained single-storey dwelling within the rear garden

The main building followed the front building line and stepped at the rear in a way that related to the footprint of the existing house and the neighbouring properties. The rear garden house was positioned lower within the plot and handled as a quieter landscape-led element in order to manage visual impact, overlooking and privacy.

This tested a more intensive use of the site shaped around frontage, plot depth, side access, neighbouring gardens and the architectural character of Westdown Road.

Access and practical feasibility

Access to the rear dwelling was to be taken through the side gap characteristic of the Westdown Road streetscape. The proposals retained this side route and used it to create a sloping stepped access of approximately 20 metres from the street to the rear house. The brief also notes that further consultation would be required in relation to emergency and fire access.

The main building was arranged with level access at entry level, shared circulation, and access to refuse and cycle storage both via the communal entrance and directly from the external side path. The overall scheme was conceived as a car-free development, supported by the site’s public transport connections.

These practical points were part of the feasibility study from the outset. Access, servicing and fire strategy were not treated as secondary matters to be resolved later.

Application to similar sites

This feasibility study is relevant to sites where:
• the existing building has failed structurally and replacement development is under consideration
• the plot depth creates scope for intensification beyond a straightforward replacement house
• the planning position is relatively open but still sensitive because of local character or non-designated heritage issues
• density, mix, landscape and access all need to be tested together at feasibility stage
• development value needs to be considered alongside planning and design logic

This project is a useful reference for deep residential plots where the planning case depends on combining demolition justification, intensification, access, landscape and housing mix into one coherent strategy.

Accommodation mix

The feasibility study tested a mix of homes intended to make efficient use of the site while remaining realistic in planning and market terms.

Garden dwelling
• 2-bedroom, 4-person single-storey home
• 70 sqm
• separate access
• large south-facing private garden amenity area

Main building

Ground floor
• Flat 01: 3-bedroom, 6-person family unit
• 95 sqm
• private south-facing garden amenity area
• communal entrance, bin store and bike store

First floor
• Flat 02: 2-bedroom, 3-person flat
• Flat 03: 2-bedroom, 3-person flat
• 61 sqm each

Second floor
• Flat 04: 1-bedroom, 2-person flat
• Flat 05: 1-bedroom, 2-person flat
• 50 sqm each

The study replaced one obsolete dwelling with a more usable mix of family accommodation, smaller flats and a separate rear-garden house. The brief notes that the proposals were intended to reflect local demand and likely buyer demographics.

Sustainability and Passive House ambition

The site’s south-facing orientation was treated as an opportunity to achieve a high level of environmental performance, and the brief records sustainability as a central consideration throughout the design stage.

The proposals were developed with a Passive House ambition, including:

• generous openings for daylight and cross-ventilation
• high levels of insulation
• airtight construction with heat recovery ventilation
• triple glazing
• LED lighting and smart controls
• rainwater collection and sustainable drainage
• solar photovoltaic and solar water heating potential
• and possible use of ground source heat pumps linked to the excavation works and partially sunken garden house

The brief also states that the project was intended to be developed further with the support of a Certified Passive House Designer or Consultant, with the aim of moving towards Passive House certification at a later stage.

We provide architectural services for residential projects in the following London Boroughs:

Barnet, Camden, Enfield, Hackney, Hammersmith and Fulham, Haringey, Islington, Kensington and Chelsea, Lambeth, Lewisham, Newham, Tower Hamlets, Waltham Forest, Wandsworth, Westminster

Home design residential guides

• Side return extensions
• Rear extensions
• Kitchen extensions
• Roof extensions
• Residential renovations
• Mansard roof extensions
• Contemporary extensions
• Flat extensions
• Garden flat extensions
• House extensions

We specialise in

• Greener homes
• Retrofit and energy efficiency for older and traditional buildings
• Conservation areas
• Listed Buildings
• Homeowner architectural services
• Property developments architectural services