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Hampstead & North London · In-house delivery

House Extension in Hampstead & NW London — Rear, Side-Return & Wraparound

House extensions across Hampstead and London — rear, side-return and wraparound forms with planning, structure and build coordinated in-house.

House extension briefs cover rear, side and wraparound additions for terraces, semis and larger homes. Design input, planning path, structural works, waterproof junctions, services and finishes are sequenced in one written programme — not a marketplace of disconnected traders.

  • House Extension
  • Rear Extension
  • Side Return Extension
  • Wraparound Extension
  • Kitchen Extension
  • Single Storey Extension
  • Double Storey Extension
  • Extension Planning Permission

Covering 224 London neighbourhoods

Get a quoteCall +44 20 7101 3168

Local decision context

House Extension briefs in priority London areas

Each link opens the dedicated service page for that neighbourhood, with local property and access context. Availability is confirmed after we review the postcode and brief.

House Extension in HampsteadNW3For a Hampstead extension brief, test the exact planning history, existing additions, boundaries, levels, drainage, tenure and site access before fixing the footprint.Open the local service pageHouse Extension in Belsize ParkNW3For a Belsize Park property, coordinate the measured plan, address-specific consent route, retained structure, neighbour interfaces and any freeholder requirements.Open the local service pageHouse Extension in St John's WoodNW8For a St John’s Wood address, confirm the relevant authority, previous development, boundary evidence, estate or tenure documents and construction access before pricing.Open the local service pageHouse Extension in HighgateN6For a Highgate extension proposal, establish the exact authority and property status, then align levels, drainage, structure, neighbours and logistics to that site.Open the local service page

Featured house extension neighbourhoods

Choose the page for your exact neighbourhood where one exists. Availability is always confirmed from your postcode.

House extension in Hampstead VillageNW3House extension in West HampsteadNW6House extension in South HampsteadNW6House extension in Swiss CottageNW3House extension in Primrose HillNW3House extension in FrognalNW3House extension in KilburnNW6House extension in Maida ValeW9House extension in Gospel OakNW3House extension in Chalk FarmNW3House extension in North EndNW3House extension in Vale of HealthNW3House extension in Hampstead HeathNW3House extension in Finchley RoadNW3House extension in Regent's ParkNW1House extension in Camden TownNW1House extension in Kentish TownNW5House extension in Dartmouth ParkN19House extension in Childs HillNW3House extension in Hampstead Garden SuburbNW11House extension in Golders GreenNW11House extension in CricklewoodNW2House extension in Mill HillNW7House extension in BrondesburyNW6House extension in Brondesbury ParkNW6House extension in Queens ParkNW6House extension in Willesden GreenNW2House extension in Lisson GroveNW8House extension in Hamilton TerraceNW8House extension in Abbey RoadNW8House extension in Highgate VillageN6House extension in Crouch EndN8House extension in Muswell HillN10House extension in Tufnell ParkN7House extension in AngelN1House extension in IslingtonN1House extension in CanonburyN1House extension in HighburyN5House extension in BarnetEN5House extension in ColindaleNW9House extension in North FinchleyN12House extension in Temple FortuneNW11House extension in TotteridgeN20House extension in WhetstoneN20House extension in Woodside ParkN12House extension in EdgwareHA8House extension in EnfieldEN1House extension in Hadley WoodEN4

Local service coverage

House Extension by area

Browse dedicated house extension pages for every area we list. Availability is confirmed after reviewing the postcode and brief.

To discuss work, start a project brief with photos and details — this portal is not a photo portfolio.

Looking for another postcode? Browse all areas or use the coverage checker.

Why Choose Hampstead On Demand?

  • ✓Reviewed by the operating team, not a provider marketplace
  • ✓The price basis is confirmed before planned work
  • ✓A written quote or confirmed call-out terms before work
  • ✓Postcode and property details considered during triage
  • ✓Relevant trade credentials checked before work

Frame the extension around household use and the existing plan

A house-extension brief should explain what the existing home cannot do and how the proposed space should connect to it. A rear family room, side-return kitchen, utility addition, accessible room or two-storey enlargement creates different daylight, circulation, privacy, service and structural questions. Mark which walls and rooms may change, how the garden should be reached and whether the home remains occupied. “Wraparound” or “rear extension” describes a form, not an evidenced design. The first output should be a clear brief and feasibility route rather than an assumed footprint or generic square-metre price.

Survey boundaries, levels, structure and buried constraints

Measured information should cover the house, previous additions, plot boundaries, ground and threshold levels, drainage points, trees, visible services, neighbouring buildings and construction access. Existing drawings, title information, planning history, surveys and service records should be assembled where held. A photograph cannot establish boundary ownership, foundation condition, drain ownership or ground bearing capacity. The designer and relevant specialists should identify what further investigation is proportionate before foundations, openings or drainage diversions are fixed. Unknowns belong in the survey plan and quote assumptions, not in confident marketing language.

Determine planning status from the complete proposal

Some house enlargements can fall within permitted-development rights in England, but only where all current conditions, limitations and cumulative-development tests are satisfied. Government technical guidance also explains that these rights do not remove other consent regimes and do not apply in every property context. Previous extensions, original-house interpretation, designated-land rules, removed rights and the relationship between rear, side and roof work can change the answer. The relevant authority or appointed planning professional should assess the exact design and address; an area hub cannot grant permission or declare an application unnecessary.

Coordinate foundations, openings and the retained building

The structural package should address the proposed foundations, ground conditions, nearby structures and drains, new walls and roof, lateral stability and openings through the existing house. Temporary support and the sequence for forming an opening matter as much as the final beam. Most extensions require Building Regulations approval, and the control route should be agreed before controlled work starts. Calculations, details and inspection stages need to align with the architectural design. A structural allowance without defined bearings, supports, fire protection and making good is not a complete construction scope.

Design drainage, thresholds and weatherproof junctions early

An extension changes roof runoff, external ground, thresholds and sometimes foul or surface-water routes. Kitchen, utility or bathroom layouts can add new drainage demand and coordination. Existing drains may cross the proposed footprint or involve a water-company or other approval route, but ownership and condition must be checked rather than assumed. The package should show roof drainage, waterproof junctions, damp protection, finished levels and how the new envelope meets the retained building. Delaying these decisions until groundworks or roofing makes avoidable changes more likely and can compromise access for inspection.

Treat boundaries and party-wall procedure as owner matters

Building on or near a boundary, working on a party structure or excavating near a neighbouring building can engage the Party Wall etc. Act. Government guidance describes this as a separate legal framework from planning and Building Regulations. The proposed foundations, wall position and structural openings need enough definition for the relevant owners and advisers to decide what procedure applies. A neighbour’s informal support is not the same as every required notice or consent, while a party-wall award does not determine the planning application. Responsibilities and lead times should be visible in the programme.

Plan an occupied-home project and its construction duties

Access, protection, temporary security, dust separation, utilities, deliveries, waste and welfare arrangements shape whether the house can remain occupied during work. Under CDM 2015, HSE explains how domestic-client duties normally pass to the contractor on a single-contractor project or the principal contractor where more than one contractor is involved, unless the permitted written arrangement applies. The project team and roles should be named rather than implied. A construction phase plan, site controls and realistic sequencing are part of delivery; a polished design alone does not manage safety or household disruption.

Price and hand over the accepted extension package

A useful proposal distinguishes design and professional fees, applications, investigations, structural work, groundworks, drainage, envelope, scaffold or access, services, finishes, protection, waste, allowances and exclusions. It should state which decisions remain provisional and how changes are approved before extra work proceeds. Programme milestones normally depend on design, consent, neighbour procedure, procurement, opening-up and inspections, so a fixed completion promise is not justified before those facts are known. Handover should assemble the agreed drawings, calculations, approvals, inspection evidence, product information, commissioning records and a written snagging status.

Independent guidance relevant to this brief

These external sources explain safety, regulatory or consumer context. They do not confirm availability, diagnose the property or replace job-specific professional advice.

House-extension design brief

  • Full address, property type, tenure and household outcome
  • Measured plans, title information, surveys and planning history if held
  • Previous extensions and all proposed rear, side and roof changes
  • Boundary, level, tree, drainage and visible-service information
  • Rooms, openings, kitchens, bathrooms and service changes required
  • Preferred materials and relationship with the retained house
  • Neighbour, party-wall, freeholder or estate constraints
  • Occupancy, access, security and programme dependencies

Extension readiness and quote checks

  • Has the complete proposal been tested against the address-specific planning route?
  • What surveys and investigations remain before structural design?
  • Which Building Regulations approval and inspection route applies?
  • How are boundaries, party structures, foundations and drains handled?
  • Who holds the designer, contractor and CDM responsibilities?
  • Which costs are fixed, allowed, excluded or subject to opening-up?
  • What approval, commissioning and completion evidence is expected?

Frequently Asked Questions

How do I start a house extension brief?▼
Use the online form or call 020 7101 3168. Include the postcode, a clear description of the issue or project, photographs where helpful, and access notes. Submission starts a review — it is not a confirmed booking.
Where do you accept house extension briefs?▼
You may submit for Hampstead, North West London and wider premium London postcodes. Dedicated pages currently focus on neighbourhoods such as Hampstead, Hampstead Village, Belsize Park, St John's Wood and West Hampstead, with other postcodes reviewed case by case. Coverage and timing are confirmed after the location and scope have been reviewed — not solely because an area page exists.
Is House Extension delivered by third-party traders?▼
No. Accepted work is routed to Hampstead Renovations or Hampstead Maintenance. We confirm the competence and any job-specific registration or insurance for the accepted scope before work starts.
How is house extension pricing confirmed?▼
Pricing depends on access, fabric condition, materials, programme and any approvals needed. Where we can quote, the written document states inclusions, assumptions, exclusions and payment terms. Smaller completed jobs are paid by bank transfer after completion; larger works use the deposit and final terms in the accepted quote.
Do I always need a site visit for house extension?▼
Not always. Clear photographs and a written description can be enough for straightforward scopes. Complex fabric, structural openings, concealed services or unclear access usually need a visit before a safe price basis can be written.
What house extension themes do people commonly brief?▼
Common themes include House Extension, Rear Extension, Side Return Extension, Wraparound Extension, Kitchen Extension. Suitability still depends on the individual property, access and the written scope we can accept after review. These tags are a guide, not a fixed menu or price list.
What freeholder or building access notes help for a house extension brief?▼
For flats and mansion blocks, attach any licence-to-alter, working-hours note, riser plan or managing-agent rules you already hold. Lift size, porter rules and communal corridor protection often affect how house extension attendance is programmed. Freeholder approval is never invented from a neighbourhood page alone — those facts come from the property documents and the accepted written scope.
Does a house extension brief always need Building Control?▼
Not always. Whether approval or a competent-person route is needed depends on the defined work and property. Openings, structural alterations, drainage changes and certain electrical or heating works are more likely to need one of those routes. We flag known compliance questions in triage. A service hub does not predict a notification outcome from a neighbourhood page. Attach any existing notice or completion certificate you hold.
Can I submit a house extension brief in London?▼
Yes. Send the postcode and job details for review. Submission is not a booking; we confirm whether the brief fits, current availability and the next step.
How is house extension work priced?▼
The price depends on the accepted scope, access, timing, materials and any assessment required. We confirm a written quote or other agreed price basis before planned work starts.
Do I need planning permission for a house extension in London?▼
It depends on design, previous alterations, designation and current local and national rules — including whether permitted development still applies. We confirm the assessment path for the specific property; formal decisions remain with the local planning authority.
How much does a house extension cost in London?▼
Cost depends on footprint, glazing, structural complexity, ground conditions, specification and whether a full kitchen fit-out is included. Market values near the area are context only — pricing follows the accepted written scope, not a postcode rate card.
Can you build a side-return or wraparound extension in London?▼
Yes, where the host house, garden and neighbours allow. Side-return and wraparound forms need careful structure, drainage and light assessment. Photographs of the rear and side elevations help triage before design lock.
Does a house extension in London need a party wall agreement?▼
Works to shared walls or excavations near a boundary may engage the Party Wall etc. Act 1996. Not every extension is a party-wall matter — formal notices and awards remain with the building owner and appointed surveyors.

More topics: all FAQs · quotes & payments · service areas · renovations

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How the brief works

1

Tell us what you need

Describe your project or issue using our online form or by phone.

2

Receive a quote

We review the request and respond with clear pricing or the next step.

3

Agree the next step

We confirm availability and agree any visit or work date with you.

4

Work delivered

Job-specific qualifications, registrations and insurance are confirmed first.

5

Follow-up

Workmanship has 12-month cover, subject to the published terms.

House Extension Guides & Resources

costs

House Extension Cost London 2026 — NW London Price Guide

House extension costs in London 2026. Single-storey, double-storey, rear and side return extensions for NW3, NW6, NW8 properties. Detailed price breakdown.

costs

Party Wall Survey Cost London 2026 — NW London Guide

Party wall surveyor fees in London 2026. Who pays, what is included, and typical costs for NW3, NW6, NW8 loft conversions and extensions.

planning

Home Extension Planning Guide — NW London 2026

Planning guide for home extensions in NW London. Single-storey, double-storey, side and rear extensions. Permitted Development vs full planning for NW3, NW6, NW8.

process

House Extension Process — Step-by-Step NW London Guide

Step-by-step guide to building a house extension in NW London. Design, planning, groundworks, structure, and fit-out. What to expect at each stage.

process

Open-Plan Living Conversions — NW London Process Guide

How to create open-plan living in an NW London home. Structural wall removal, RSJ beams, planning, and what open-plan conversion costs. Expert guide.

process

Garden Office Studio Guide — NW London Planning & Build Process

How to build a garden office or studio in NW London. Permitted Development rules, insulation, electrics, and planning in conservation areas. Complete guide.

In-depth reading

Cost guide

House Extension Cost London 2026 — NW London Price Guide

Cost guide

Party Wall Survey Cost London 2026 — NW London Guide

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