Building a New Home in London: Self-Build, Developer Sites and Full-Build Process

Land in London is scarce and expensive. Common sources of building plots include:

Specialist plot search websites: plotfinder.net, landregistry data releases, and local estate agents who specialise in development sites are the most efficient sources. Plots are rarely advertised widely — most trade through networks.

Infill opportunities: gaps between existing houses, corner plots, redundant commercial properties in residential areas (subject to change of use planning), and large garden plots are the most common infill opportunities in the London context.

Demolish and rebuild: where an existing property is structurally sound but outdated, it can sometimes be more cost-effective in the long run to demolish and start fresh — particularly where the existing layout is inefficient, the structure has significant defects, or the client wants a fully modern building.

Former local authority sites: some London boroughs release small sites for custom and self-build development. The Right to Build scheme (introduced by the Housing and Planning Act 2016) requires local authorities to maintain a register of self-build applicants and release sufficient serviced plots to meet demand. In London, progress on this has been limited but the policy continues to develop.

Planning permission required: building a new dwelling almost always requires full planning permission. Permitted development rights for new dwellings are extremely limited.

London Plan and borough policies: all London boroughs must comply with the London Plan (the spatial development strategy for Greater London, produced by the Mayor of London) as well as their own Local Plan. Policies covering design quality (using Urban Design principles and the London Design Guide), housing density, parking, sustainability, and heritage context all apply.

Design quality expectations in London: London planning authorities expect high-quality design. Many boroughs will require a design and access statement justifying the architectural approach in the context of the existing street or site. Conservation area applications require particular attention to character.

Viability and affordable housing: for sites producing more than a threshold number of units (which varies by borough), affordable housing contributions or a financial contribution to off-site provision may be required. For single-dwelling infill projects this is typically not applicable, but advice should be sought.

Self-build (client-managed): the client acts as their own project manager and engages an architect, structural engineer, and individual trade contractors directly. This route offers the most control and can be the most cost-effective in gross build cost, but requires significant time commitment, a high tolerance for coordination risk, and detailed knowledge of construction sequencing. It is most suitable for experienced clients or those who plan to be highly involved in the project.

Contractor-led (design-and-build): a main contractor is engaged to deliver the project from a design that has been developed (typically to planning stage) by an architect. The contractor takes responsibility for procurement and coordination of trades. This route transfers more risk to the contractor, reduces the client's day-to-day management burden, and provides a clearer commercial framework through a fixed-price or schedule-of-rates contract.

Turnkey / design-and-build from concept: a design-and-build contractor (such as rcbGroup) develops the design from concept through planning through technical design to delivery under one organisation. This is the most integrated approach and reduces the risk of design and build being disconnected.

Package house or timber frame system: for clients seeking faster build times or greater certainty of thermal performance, modern timber frame or structural insulated panel (SIP) systems offer accurate factory-manufactured superstructures erected quickly on site. These systems are common in Scotland and the Republic of Ireland and are growing in the London market.

1. Feasibility and site assessment: confirming planning potential, access constraints, utilities availability, ground conditions, and preliminary budget viability.
2. Concept design and planning pre-application: engagement with the planning authority before submitting an application to understand their likely response to the proposed scale and design.
3. Planning application: submission and determination (typically 8 to 13 weeks for a planning decision).
4. Technical design and specification: detailed architectural drawings, structural engineering, M&E coordination, and specification of finishes and systems.
5. Contractor procurement: inviting tenders, evaluating and appointing a main contractor.
6. Construction: groundworks and foundations, structure, weatherproofing, first-fix services, insulation and boarding, plastering, second-fix and finishes.
7. Building Regulations sign-off and completion.
8. Snagging and handover.

New build costs in London are among the highest in England due to labour costs, land values, and logistics.

• Professional fees (architect, structural engineer, planning consultant): 12 to 18 per cent of construction cost
• Groundworks and foundations (typically deeper than the national average due to London clay): £30,000 to £80,000+
• Superstructure (walls, roof, windows and external doors): £80,000 to £150,000+ depending on construction method
• First-fix services (plumbing, electrics, heating): £30,000 to £60,000
• Insulation, boarding, plastering: £20,000 to £40,000
• Second-fix and finishes (joinery, kitchen, bathrooms, decoration): £40,000 to £100,000+

Typical total construction cost for a new 3-bedroom, 2-bathroom semi-detached house in London (approximately 120m2): £280,000 to £500,000, exclusive of land, professional fees, and planning costs. Costs at the higher end of this range reflect higher specification finishes, challenging ground conditions, or premium locations with access and logistics constraints.