House Extensions Hornchurch
Single storey rear and double storey extensions in Hornchurch, 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 home extensions across Hornchurch, where 1930s semis and post-war houses sit on generous plots that suit rear and side additions. We handle foundations, steelwork, roofing and full fit-out, and guide you through permitted development or a planning application to Havering Council.
In Hornchurch, 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 Hornchurch: 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 Hornchurch
Hornchurch range: choose above
Kitchen extensions and side additions in Hornchurch
The wide plots that characterise Hornchurch give real scope for extending. A single storey kitchen extension across the back of a 1930s semi or post-war house creates an open-plan kitchen-diner that opens onto the garden, while the space down the side of a detached or semi-detached house suits a side-return or wrap-around that squares off the ground floor. We begin with trial holes and properly designed foundations, because interwar houses were built with shallower footings than modern regulations require.
From there we form the openings with engineer-designed steel beams, build up in matching brick, tie in the new roof and install the glazing, then complete the internal fit-out. Because a rear extension of a Hornchurch semi typically involves work near or on the party wall, you serve the correct notices to neighbours. Every element is inspected by Havering building control, from foundations and drainage to insulation and the finished structure.
Housing in Hornchurch
The valuation list shows roughly 9,530 homes in Hornchurch, of which 3% are pre-1919, 48% interwar and 49% post-1945, split 26% flats to 75% houses. A rear extension on a terrace in Hornchurch digs foundations close to both neighbours, so notices to both are normal, and 23% of homes here are terraced.
Rear extensions on Hornchurch semis and the prior approval route
Havering's prior approval route is for larger single storey rear extensions of up to 6m for an attached property or up to 8m for a detached property. In Hornchurch 41% of homes are semi-detached or detached, and that split matters: a semi counts as attached, so its limit is the shorter one, however generous the garden. The route is not open to a house in a conservation area, where the ordinary, shorter limits apply. Neighbours are consulted on a prior approval application, so a deep extension on a Hornchurch semi is best discussed next door early, alongside any party wall notice the building owner serves for the foundations.
The other early check is below ground. Havering requires a full plans application, not a building notice, where you are building near a public sewer, and behind a semi or a terrace the shared drain run can cross the garden close to the house. A drain survey with a camera, done before the footprint is drawn, tells the engineer where the sewer runs and how deep it sits. If the extension lands over or beside it, the application goes in on full plans and the water company's agreement to build over or near the sewer is sought. The foundation design then deals with the pipe, rather than the drainage turning up when the trench is dug.
Permitted development or planning in RM11
Many single storey rear extensions on Hornchurch houses fall under permitted development, meaning they can proceed without a full planning application provided they stay within the size, height and boundary limits the rules set. On the larger interwar plots this often gives generous scope. We assess your property against the current criteria and, where it qualifies, recommend a lawful development certificate from Havering Council to confirm the position in writing.
Double storey extensions, wrap-arounds, work that fronts the street or anything beyond permitted development limits will need a full planning application to Havering Council, which your architect or designer prepares; we can recommend one and coordinate the submission with them. Whichever route applies, building regulations still govern the structure, so foundations, beams, insulation, fire safety and drainage are inspected regardless. We are clear from the outset about which consent your specific project needs so there are no surprises.
Double storey extensions in Hornchurch
Under permitted development a two-storey rear extension can go no more than 3 metres beyond the original rear wall and must stay at least 7 metres from the rear boundary, and in a conservation area it is not permitted development at all. Many gardens are too short for the 7 metre rule, so a double storey extension in Hornchurch often needs planning permission from Havering Council. With 41% of homes here semi-detached or detached, the side of the house is often an option too. Langtons Conservation Area was designated in 2010 and lies to the north west of Hornchurch town centre (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Insulation, airtightness and thermal detailing to regulations
- Levels, drainage and landscaping made good around the new build
- Trial holes to set foundation depth near drains and trees
VOA Council Tax stock of properties, March 2025, for Hornchurch, Emerson Park and Hylands. Counts rounded by the VOA.
Trusted House Extensions in Hornchurch
Hornchurch homeowners choose GS Renovation because one team takes the extension from first survey to final decoration. We build foundations beside interwar footings to the engineer's design, install the steel the engineer has sized, and coordinate the permitted development or planning route with Havering Council. With our founder's 30+ years on the tools, you get honest advice, building control sign-off and a well-built result.
- Straight advice on what is and is not worth spending money on
- Brick and mortar matched to the existing elevation
- 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 was very friendly and helpful from start to finish. He worked really hard to ensure our kitchen was installed to a high standard and was…
Giorgio is an excellent and intelligent workman, and with very reasonable prices! He installed a kitchen extractor fan in a complicated situation…
FAQ
Frequently Asked Questions about House Extensions Hornchurch
What drives the cost of house extensions in a Hornchurch home?
What sits behind the walls moves the price of house extensions in Hornchurch far more than the address does, within £2,000 to £2,800 per m² for a rear extension (indicative). In practice the drainage run under the footprint decides the foundations, and that is only settled at the RM11 survey. Older Havering stock adds making good and awkward access adds labour, so both are itemised. Ring 07472 424 226 before comparing figures.
Will my Hornchurch rear extension need planning permission?
Many single storey rear extensions in Hornchurch fall under permitted development and need no planning application, especially given the generous interwar plots, though a lawful development certificate from Havering Council is worth having. Double storey extensions, wrap-arounds or anything beyond the limits do need planning permission. Either way, building regulations apply, and we confirm the route before we start. A listed building is the exception: work that affects its character, inside or out, including an extension or taking out a wall or chimney breast, needs listed building consent from Havering Council, and doing it without consent is a criminal offence.
At which points does building control visit a Hornchurch extension?
At the foundation trench before concrete, again at damp-proof course level, at drainage before it is backfilled, and when insulation and structure are visible before they are covered, then at completion. Havering Council issues the final certificate after that last visit. Each stage is booked in advance, because work cannot be hidden until the inspector has signed it off.
Can we stay in our Hornchurch house while the extension is built?
Usually, if the sequence is planned around you. The new shell is built and made watertight while the old back wall stays closed, so the house is still sealed. Only then is the opening formed with steel and the two spaces joined. That keeps the disrupted period short, although the kitchen is often out of action while the join is made.
What insulation will my Hornchurch extension need?
It must meet current Part L standards in the walls, floor and roof, which are far higher than the original house achieves. That shapes wall thickness and roof depth. Large glass areas count against the calculation, so a heavily glazed design may need better-performing walls or roof to compensate. The figures are checked before building control approves the plans.
Why dig trial holes before building an extension on a Hornchurch house?
To see what the existing house is standing on. Interwar strip footings in Hornchurch were shallower than a new foundation will be, and the new footing must not undermine the old one where they meet. Trial holes show depth and ground type, so the engineer can design the junction and building control can agree it before the main trench is dug.
Why does the floor area of a Hornchurch extension matter to the building control charge?
Havering sets its extension charges in floor area bands: not exceeding 30 square metres, over 30 but not over 60, and over 60 but not over 100, including means of access. Measure the floor area before the design is fixed. A kitchen extension drawn just over a threshold moves into the next band, so a small trim to the plan can keep it in the lower one without losing anything useful in the room.
Do we need to tell Havering before demolishing an old garage behind a Hornchurch house?
Havering asks anyone planning to demolish a building to give at least six weeks' notice before starting, and it charges a demolition notice fee for small schemes up to the size of a single dwelling. The law exempts some small outbuildings, so ask building control whether an old garage cleared for the extension counts, and raise it when the extension application goes in. Leaving the question until the skip arrives can hold the start back by weeks.
Is written planning advice worth getting before a Hornchurch extension application?
For a scheme that needs a householder planning application, it often is. Havering offers written pre-application advice on householder extensions and alterations, aiming to reply within 20 working days of the request. Send drawings, photographs of the neighbouring houses and a site plan, and ask a specific question about depth, height or the side wall. The reply then shapes the application, rather than a refusal forcing a redraw and a second submission.
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