House
extensions
in Holborn, WC1
Architects, Engineers, Surveyors & Builders Under One Roof.
One Studio. One Contract. One Team.
RICS surveying support for party walls, licence to alter, conservation-area works & neighbour mattersWe design and build Holborn house extensions across Lincoln’s Inn Fields, Red Lion Square, Bedford Row - side-return, rear, wraparound and double-storey additions for Georgian terraces, Victorian Chambers and larger family homes where planning strategy, conservation detailing, Party Wall sequencing and structural engineering need handling properly.
House Extensions in Holborn: What You Need to Know
Every house extension project in Holborn is designed to respect the Bloomsbury & Holborn Conservation Area and the character of Georgian terraces, Victorian chambers, mansion flats. Our in-house RIBA Chartered Architects handle Camden planning applications, our chartered structural engineers specify any load-bearing work, and our directly-employed trades deliver the build under one fixed-price contract. We coordinate Building Control, Party Wall awards where needed, and all certifications through to handover.
In Holborn's conservation area, extensions must be designed with exceptional sensitivity. Camden officers assess impact on the host building, neighbouring properties, and the wider streetscape. We secure planning approval through design excellence and thorough pre-application engagement.
Historic area around Lincoln's Inn Fields with Georgian architecture and legal quarter character. Camden planning policies with significant listed building stock. Our extensions in Holborn use materials and detailing that complement the existing architecture — whether matching traditional brickwork and stonework or introducing high-quality contemporary glazing and zinc cladding.
Extending a house in Holborn means working within the historic legal quarter. It sits in Camden, within the Holborn and Bloomsbury conservation areas around the Inns of Court, where the chambers and mixed-use buildings add their own constraints and Camden applies Article 4 controls alongside close scrutiny of external change.
The costs reflect that dense, commercial grain. WC1 access, lifts and loading, work in or above commercial premises, listed and positive-contribution frontages, shopfront controls, plant and service routes, fire and acoustic upgrades, party walls and archaeology all feed into the number, as does the cost of sequencing works in constrained central blocks.
Bedford Row and Great James Street carry fine Georgian terraces, some still chambers and some returned to homes, while Red Lion Square and Lamb's Conduit Street add period houses and conversions. By the Camden benchmark a single-storey rear extension costs £71,250–£112,500 excluding VAT and a side return £90,000–£120,000 excluding VAT.
What a House Extension Involves
An extension reshapes how the whole ground floor works, not just how big it is — the new structure, the opening into the existing house, the kitchen and the garden connection all have to be designed as one move. We take each project from feasibility drawings through consents, structure and fit-out under a single fixed-price contract. Most extensions we build include the scope below.
- Rear extensions — single-storey additions that open the back of the house to the garden
- Side-return & wraparound — infilling the side alley of a terrace, alone or combined with a rear addition
- Double-storey — new bedrooms or bathrooms above the ground-floor addition, designed to sit comfortably with the original roofline
- Foundations & steel — groundworks, beams and the opening into the existing house, engineered by our own structural team
- Glazing — rooflights, glazed roofs and slim-framed sliding or bi-fold doors specified for light and thermal performance
- Kitchen integration — the kitchen layout planned with the architecture from the first drawing, not squeezed in afterwards
- Services & heating — electrics, plumbing, drainage and underfloor heating built into the new floor
- External works — patio, drainage connections and garden reinstatement completed within the contract
How We Run Your Project
Six stages, with the consents and engineering settled before the first spade goes in.
- Feasibility visit — we assess the site, the boundaries and your brief, and identify the right consent route for your property.
- Design & approvals — our architects draw the scheme while planning or permitted development paperwork, structural calculations and party wall notices progress together.
- Fixed-price contract — every element specified and priced before construction, from foundations to door hardware.
- Groundworks & shell — excavation, foundations, walls, steel and roof, taken to weathertight while you carry on living in the house.
- Fit-out — insulation, services, glazing, kitchen, flooring and decoration, with the opening into the existing house formed once the shell is sealed.
- Completion — building control inspection, snagging, external works and handover with the full certification pack.
Read the full house extension guide for extension types, permitted development limits and the build programme stage by stage.
Many rear extensions can proceed under permitted development — broadly up to 3m deep on attached houses and 4m on detached, extendable to 6m and 8m through the prior approval scheme — but conservation areas, Article 4 directions and listed status change the picture, and every extension needs Building Regulations approval regardless of the planning route. Where foundations come within 3m of a neighbouring building, the Party Wall etc. Act 1996 obliges you to give adjoining owners a minimum of two months’ written notice before construction can begin. Our planning guide library sets out the rules for each borough.
Why Hampstead Renovations
We hold £10 million public liability insurance with Aviva; the certificate is available on request.
House Extensions in Holborn: Questions
What is distinctive about extending in Holborn?
Its setting in the legal quarter. Holborn sits within the Holborn and Bloomsbury conservation areas around the Inns of Court, where the chambers and mixed-use buildings add their own constraints, and Camden applies Article 4 controls alongside close scrutiny of external change.
What extra costs come with Holborn's commercial fabric?
A number of them: WC1 access, lifts and loading, work in or above commercial premises, listed frontages and shopfront controls, plant and service routes, fire and acoustic upgrades, party walls and archaeology, plus the cost of sequencing works in constrained central blocks.
What does a house extension cost in Holborn?
For a single-storey rear extension the Camden figure is £71,250–£112,500 excluding VAT, with a side return at £90,000–£120,000 excluding VAT and a wraparound at an indicative market band of £100,000–£200,000.
How does Camden assess a Holborn scheme?
Using conservation-area appraisals and statements for the Hatton Garden, Kingsway, Bloomsbury and Denmark Street contexts, with heritage justification and address-level review of listed buildings, shopfronts, archaeology, trees and mixed commercial and residential use.
Which Holborn streets suit extensions?
Bedford Row and Great James Street carry fine Georgian terraces, some still chambers and some returned to homes, while Red Lion Square and Lamb's Conduit Street add period houses, flats and conversions in a tight historic grid.
House Extensions in Nearby Areas
More Services in Holborn
Book a Free Consultation
Visit our studio or invite us to survey your home. We’ll assess scope, discuss design possibilities and provide an honest budget framework — completely free.
Free Consultation
We survey your property, discuss your vision and provide a clear budget framework.