House Extensions Angel
Single storey rear and double storey extensions in Angel, planning, structure and build under one contract.
- Rated 4.9 from 31 reviews on MyBuilder
- Single-storey rear extension from £40,000
- Free site survey, itemised quote
GS Renovation plans and builds house extensions throughout Angel and N1, adding space to Georgian and Regency townhouses and converted period homes near Upper Street and Barnsbury. We handle groundworks, steelwork, roofing and fit-out, and guide you through planning and party wall matters from the outset.
In Angel, a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m² (indicative London ranges, Architecture for London, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Angel: the structural engineer we appoint designs the structure, we build it, and building control signs it off.
Price guide
| Work | Indicative London range |
|---|---|
| Single-storey rear extension | from £40,000 |
| Rear extension, per m² | £2,000 to £2,800 |
| Side return, per m² | £2,400 to £3,200 |
| Wraparound, per m² | £2,400 to £3,200 |
| Double storey, per m² | £1,800 to £2,600 |
| Basement extension | see the basement page |
Indicative London ranges (Architecture for London, Resi, MyBuilder and Checkatrade, 2026), not a quotation. Prices checked September 2026. Full breakdown: Extension Costs & Planning.
Quick estimate for Angel
Angel range: choose above
Rear and side-return extensions in Angel
Houses are a minority in Angel, where most homes are flats, but on the terraces that remain the classic project is a side return extension: it takes in the narrow side return of a period terrace, widening the ground floor into a kitchen extension and bright kitchen-diner opening onto the garden. Most are single storey, with the new roof sloping down from the party wall so next door keeps its light. We dig and lay foundations to suit the ground and any nearby trees, install steel beams where the rear wall is opened up, and build the new roof and glazing. Every stage is inspected under building regulations so the finished structure is certified.
Whether your project is permitted development or needs a full planning application depends on the property. Many N1 homes sit within Islington conservation areas or are listed, which restricts permitted development rights, so an application to Islington Council is often required. We assess your specific address early, advise honestly on the route, and give you the drawings for the party wall notices you serve on neighbours whose boundary the works affect.
Housing in Angel
For Angel the Council Tax list gives about 19,540 homes; by type 84% flats and 16% houses, by age 44% post-war, 3% interwar and 52% older than 1919. Most homes here are flats, and a flat in Angel has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
The Angel conservation area limits on rear extension height
The Angel conservation area (CA18) has design guidelines adopted in January 2002, and they are specific about rear extensions. They say full width rear extensions higher than one storey, or half width rear extensions higher than two storeys, will not normally be permitted. For an Angel terrace that narrows the choice to two shapes: a single storey across the whole back, or a narrower wing that stops at two storeys. A full width two storey box is starting from a position the guidelines say is not normally acceptable. We ask the designer to draw inside those shapes first, then test anything bolder with the planners.
Before any shape, the tenure. Houses are 16% of Angel homes, and Islington Council says you need to apply for full planning permission to add an extension or conservatory to a flat. A garden flat in a converted house therefore starts with an application and the freeholder's licence, not a permitted development check. Behind the terraces the new floor may also cross a drain, and Islington says a building notice cannot be used when building over existing sewers and drains. A drain survey at the start tells you which building control route and which foundation design the extension needs.
Double storey space for N1 townhouses
Tall Georgian and Regency townhouses in Angel lend themselves to considered rear extensions over one or two storeys, adding a larger kitchen below and a bedroom or bathroom above. We match brickwork, detailing and proportions to the age of the house so the addition sits comfortably with the original, which matters greatly in Islington's conservation streets where the council scrutinises how changes read from front and rear.
The build brings together foundations, structural steel, a weathertight roof and a full internal fit-out, all sequenced by one team so trades do not clash. We manage the building control inspections at each key stage, from foundations to insulation and drainage, and plan the programme around the party wall notices you serve where the extension is built up to or astride a shared boundary with your Angel neighbours.
Kitchen extensions in Angel
84% of homes in Angel are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Islington Council and the freeholder's consent. Most kitchen extensions here are on the 16% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Angel; the build figures are in the table above.
- Single and double storey extensions
- First fix and second fix plumbing and electrics throughout
- Brickwork and mortar matched to the existing elevation
VOA Council Tax stock of properties, March 2025, for Angel, Barnsbury East, Barnsbury West and Pentonville. Counts rounded by the VOA.
Why Choose GS Renovation in Angel
Angel homeowners choose GS Renovation because extending a period or listed N1 home needs a builder who understands both the structure and Islington's planning reality. We advise early on permitted development versus a planning application, manage groundworks, steel and roofing, programme around the party wall process, and deliver a fully certified extension. Our founder's 30+ years on the tools backs every project.
- Materials priced at options, so you choose the finish
- Foundation depth set after trial holes, drains and trees are checked
- Building control inspected at foundation, damp course and steel stages
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
George always kept to commitments and arrived on time. He offered helpful suggestions during his initial visit and promptly provided a reasonably…
Saaid is the best craftsman I have worked with. He knows what he is doing from the very beginning. He has a great knowledge of construction…
FAQ
Frequently Asked Questions about House Extensions Angel
Are there hidden costs with house extensions in Angel?
Hidden costs on house extensions in Angel come from what the N1 survey cannot see, not from the quotation, which sits within £2,000 to £2,800 per m² for a rear extension (indicative). Older property can uncover wiring, timber or drainage, and GS Renovation names what it suspects before starting. Approvals are never a surprise extra: building regulations approval from foundations to completion is priced from day one.
Will my Angel extension need planning permission or is it permitted development?
Many Angel homes fall within Islington conservation areas or are listed, which reduces or removes permitted development rights, so a planning application to Islington Council is often needed. Straightforward single storey rear extensions on unlisted houses can sometimes proceed under permitted development, but flats have no householder permitted development rights. We check your exact address first and advise on the correct route before any work starts.
What if a sewer runs under the planned extension at my Angel house?
A drain survey settles it early. Behind Islington terraces the shared run is often a public sewer, and the water company has to consent before anyone builds on top of it or close beside it, which can change the footprint. Manholes inside the new floor area are moved or fitted with sealed covers, and building control checks the falls before the slab is cast.
Which building control visits does an Angel extension go through?
Several: the foundation trench before concrete, drainage before it is buried, the damp proof course and oversite, the steel where the house is opened up, and a final visit for the completion certificate. Islington Council's inspector must see each stage, so the programme is arranged around those visits rather than the other way round.
How is the back wall opened into a new extension on an Angel terrace?
With steel, ideally once the shell is weathertight. The engineer designs a beam for the old back wall's load and the storeys over it, props go in, and the wall comes down only after the new roof keeps rain out. On a terrace one beam end commonly lands in the shared wall, and that bearing is notified to the neighbour two months or more ahead.
What insulation standard must an Angel extension meet?
Current Part L, which is far tighter than anything in the original house. Walls, floor and roof are insulated to present standards, and glazing area is weighed against them, so a big lantern may need compensating elsewhere. Where the new work meets solid Georgian brick, the junction is detailed so the warm new wall does not drive damp into the old one.
Does a tree in an Angel garden affect when an extension can start?
It can. In an Islington conservation area you must give the Council six weeks notice in writing before any work is carried out to prune or fell a tree. If the extension needs a tree cut back for the footings, the scaffold or the new roof, that notice goes in as soon as the footprint is settled. The structural engineer we appoint also needs to know the species and distance, because roots can set the foundation depth.
Is Islington's pre-application advice worth it for an Angel extension?
For anything near the CA18 limits, usually. Islington offers householder pre-application written advice, a version with a site visit, and follow-up advice, and its planning pre-application fees increased on 2 January 2025. On an Angel street the officer's view on height, width and materials before the drawings are final is cheaper than a refusal. Book the site visit version where the rear cannot be seen from the street, so the officer sees the garden and the neighbouring windows in person.
Does the Community Infrastructure Levy apply to an Angel house extension?
Check before the application goes in. Islington's CIL charging schedule, approved on 26 June 2014 and in effect from 1 September 2014, sets a rate per square metre for residential dwellings. Islington Council states that the Mayor of London's CIL is charged per m2 of development in the borough too. Whether a particular extension is liable turns on its size and on any exemption or relief, so the planning agent confirms it with the application.
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