The whole spectrum — rear extensions, side returns, wraparounds, double-storey, basement digs. Planning-led design with detailed technical phase, ideal for 1930s semi-detached dominates typical of Barnet.
The whole spectrum — rear extensions, side returns, wraparounds, double-storey, basement digs. Planning-led design with detailed technical phase, ideal for 1930s semi-detached dominates typical of Barnet.
Housing stock in Barnet: 1930s semi-detached dominates; Edwardian villas in Muswell Hill, Finchley; Garden Suburb Arts & Crafts in Hampstead Garden Suburb; post-war flats in Colindale.
Character: Suburban outer-London borough; permitted development used heavily; Hampstead Garden Suburb has its own residents' trust with additional design controls.
Measured existing survey, photographic record, Article 4 and conservation check specific to Barnet before we quote.
2–3 design options at concept stage — alternative layouts, glazing, roof forms.
Site location plan, existing and proposed plans, elevations, sections, D&AS where required.
Part L thermal, Part B fire, Part M accessibility, structural strategy.
Steel beam, foundation, lintel design. Chartered engineer sign-off.
Party Wall notices where needed; Thames Water Build Over Agreement where within 3m of a public sewer.
Single planning or regs submission.
Planning + building regs + structural.
Listed, conservation, complex sites.
Direct answers to the questions Barnet homeowners ask every week about house extension drawings.
Start a free quote →Most standard extensions in Barnet qualify as Permitted Development — single-storey rear up to 3m/4m, side extensions up to half the width of the house, under standard national rules. Flats, listed buildings and conservation areas need full planning permission. We confirm eligibility at the free site survey.
Standard permitted development allows single-storey rear extensions up to 3m (attached house) or 4m (detached) in Barnet. Larger extensions up to 6m/8m are allowed under Prior Approval (Class AA). Flats, listed buildings and Article 4 areas in Barnet are excluded from these PD rights.
Our fixed-fee architectural package starts at £1,225 for a Barnet extension (planning + building regs + structural). Typical Barnet build costs are £2,400–£3,500 per square metre including VAT — so a 25m² side return extension is £60,000–£87,500 to construct.
Barnet does not have a borough-specific basement policy beyond the national framework — basement conversions are generally permissible subject to structural, drainage and flood-risk considerations. Thames Water Build Over Agreements apply where you're within 3m of a public sewer.
Most Victorian terraces in Barnet (particularly in Hampstead Garden Suburb) benefit from both — a side return extension infills the narrow side passage to create a wider kitchen, a rear extension projects back into the garden. A wraparound combines the two. We recommend the best option at the free site visit.
Barnet's 1930s semi-detached dominates terraced and semi-detached stock typically suits rear single-storey extensions (kitchen-diners), side-return infill extensions, or double-storey rear. Wraparound extensions combine both directions for maximum gain. We recommend the most viable option at the free site visit.
We cover all Barnet postcodes — {postcodes} — with local surveyors. Survey appointments within 3 working days. Fixed fees — no hourly billing.
Barnet Council follows the London Plan and its own Local Development Framework. Extensions must match or complement existing materials, respect neighbour amenity and comply with Part L. We include a Pre-Application Advice summary where the planning history is complex.
We cover every London borough with the same fixed-fee approach. If your property sits on a boundary, here are the neighbouring options.
We cover every architectural technology service in Barnet with one chartered team.
From £840. A fixed-fee, end-to-end service — measured survey, scaled drawings, Design & Access Statement where required, Planning P...
From £840. A construction-ready drawing package compliant with every Approved Document — Part A structure, Part B fire, Part L ther...
From £1,225. Every loft type across every Barnet roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning rout...
From £1,575. Barnet's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that ...
From £995. Turn your unused Barnet garage into a bedroom, home office or open-plan kitchen-diner. Planning route assessment, full b...
From £1,950. Full architectural technology service for basement digs and cellar conversions in Barnet — structural underpinning desig...
From £350. Chartered structural engineer calculations for every residential intervention in Barnet — steel beams, lintels, pad foun...
From £540. Fixed-fee measured surveys across Barnet from £540 — floor plans, elevations and sections to ±3mm accuracy. Leica Disto ...
From £450. End-to-end Party Wall Act 1996 service for Barnet — Section 1, 3 and 6 notices, schedule of condition surveys, party wal...
From £1,225. London's most popular loft type — the full-width rear dormer. Planning or Permitted Development route assessed for your ...
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Free quote in 60 seconds. Fixed fee from £1,225. MCIAT chartered.
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