The whole spectrum — rear extensions, side returns, wraparounds, double-storey, basement digs. Planning-led design with detailed technical phase, ideal for very limited residential — Barbican Estate (listed post-war), Golden Lane Estate, modern luxury flats typical of City of London.
The whole spectrum — rear extensions, side returns, wraparounds, double-storey, basement digs. Planning-led design with detailed technical phase, ideal for very limited residential — Barbican Estate (listed post-war), Golden Lane Estate, modern luxury flats typical of City of London.
Housing stock in City of London: Very limited residential — Barbican Estate (listed post-war), Golden Lane Estate, modern luxury flats; overwhelmingly commercial.
Character: Overwhelmingly commercial; residential planning extremely constrained; listed building density the highest of any London borough.
Article 4: Multiple Article 4 Directions around office-to-residential, demolition, and shopfront changes.
Measured existing survey, photographic record, Article 4 and conservation check specific to City of London 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 City of London homeowners ask every week about house extension drawings.
Start a free quote →Most standard extensions in City of London fall under Permitted Development — single-storey rear up to 3m (attached) or 4m (detached), side returns up to half the width of the house. However, City of London has Article 4 Directions that may remove these rights in specific streets, and flats, listed buildings and conservation areas always need full planning. We check PD eligibility before quoting.
Standard permitted development allows single-storey rear extensions up to 3m (attached house) or 4m (detached) in City of London. Larger extensions up to 6m/8m are allowed under Prior Approval (Class AA). Flats, listed buildings and Article 4 areas in City of London are excluded from these PD rights.
Our fixed-fee architectural package starts at £1,225 for a City of London extension (planning + building regs + structural). Typical City of London 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.
City of London 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 City of London (particularly in Barbican) 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.
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 City of London 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 {location} roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning ...
From £1,575. {location}'s most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards t...
From £995. Turn your unused {location} garage into a bedroom, home office or open-plan kitchen-diner. Planning route assessment, fu...
From £1,950. Full architectural technology service for basement digs and cellar conversions in {location} — structural underpinning d...
From £350. Chartered structural engineer calculations for every residential intervention in {location} — steel beams, lintels, pad ...
From £450. End-to-end Party Wall Act 1996 service for {location} — Section 1, 3 and 6 notices, schedule of condition surveys, party...
From £1,225. London's most popular loft type — the full-width rear dormer. Planning or Permitted Development route assessed for your ...
Free quote in 60 seconds. Fixed fee from £1,225. MCIAT chartered.
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