House Extensions Across London & the South East
Covers Of London designs and builds house extensions for homeowners across the capital — rear extensions, side return infills, wrap arounds and double storey builds. Based in Hackney, working London-wide. Our in-house team handles everything from architectural drawings and planning through to the finished build. Fixed pricing, no sub-contractors, and a 10-year guarantee on every project.
30+
YEARS IN THE TRADE
3,500+
PROJECTS COMPLETED
Fixed
PRICE QUOTATIONS
10yr
WORK GUARANTEE
EXTEND, DON’T MOVE
House Extensions Built by Our Own Team, Start to Finish
The cost of moving in London — stamp duty alone can run into tens of thousands — makes house extensions a considerably more practical route for families who need additional space. A well-built ground floor extension adds usable square footage to the part of the house where most people actually spend their time, and the value it adds to the property usually outstrips the build cost within a few years.
We manage the full process in-house. Architectural design, structural engineering, planning applications where they are needed, party wall agreements with neighbours, groundworks, structural steelwork, the full build programme, and every second-fix trade — electrics, plumbing, plastering, tiling, decoration. One project manager oversees the job from survey to sign-off. No sub-contractors, no agency workers, and no handing the project off to a different team halfway through.
EXTENSION TYPES
Types of House Extension We Build
Rear Extensions
A rear extension pushes the back of the property further into the garden, creating a larger kitchen, open-plan dining area or family room. Under current permitted development rules, you can extend up to 4 metres to the rear on a detached house and 3 metres on a terraced or semi-detached — though there are exceptions, and we always confirm the specific rules for your property and borough before quoting.
Most of the rear extensions we build in London include full-width bi-fold or sliding doors that open onto the garden, a flat roof with one or more skylights for overhead light, and an internal layout designed around how you actually use the ground floor. We regularly build rear extensions on properties across Hackney, Dalston, Clapton, Bethnal Green, Stratford, and throughout East London.
Side Return Extensions
That narrow alleyway running alongside your kitchen — between the rear outrigger and the boundary fence — is wasted space on most London terraces. A side return extension fills it in, widening the ground floor by a surprisingly useful amount without touching the garden.
This is one of the most popular extension types across East London and particularly suited to the Victorian terraces found throughout Hackney, Stoke Newington, Islington, Clapton and the surrounding streets. The infill alone can add 10 to 15 square metres of usable kitchen or living space, and because the area is narrow, the build is often less disruptive than you might expect. Side return extensions frequently fall within permitted development rights, though we always verify this during the survey.
Wrap Around Extensions
A wrap around combines a rear extension with a side return infill, creating an L-shaped addition that produces the largest possible ground floor footprint from a single storey build. The typical result is a substantial open-plan kitchen, dining and living space that fundamentally changes how the ground floor works.
Wrap arounds require more structural steelwork than a standard rear or side return on their own, and may need planning permission depending on the overall size and your property’s planning status. We handle the full structural design and any planning applications as part of the service. For families in London who need the maximum amount of additional space without building upward, a wrap around is usually the strongest option.
Double Storey Extensions
Where additional bedroom or bathroom space is needed on the first floor as well as the ground floor, a double storey extension delivers considerably more living space for a relatively modest increase in cost over a single storey. The lower level is typically used for kitchen and living space, while the upper level accommodates bedrooms, en-suites, or a home office.
Double storey extensions involve more structural complexity — deeper foundations, heavier steelwork, and more extensive scaffolding — and almost always require planning permission. Properties in Barnet, Enfield, Walthamstow, Woodford, Chingford and the outer boroughs, where semi-detached and detached houses are more common, are frequently well suited to this type of build. We manage the planning application, structural design, and the full construction programme.
WHAT’S INCLUDED
Our House Extension Design & Build Service
Every extension we take on is delivered as a single design and build contract. One team, one price, one point of accountability throughout.
Free on-site survey — we visit the property, assess the site, discuss your requirements, and advise on the best type and size of extension for the available space.
Architectural drawings & structural engineering — produced to the standard required for building control and any planning submissions.
Planning & party wall management — we prepare and submit applications, serve party wall notices on neighbours, and manage the process from start to completion.
Full construction — groundworks, foundations, structural steelwork, walls, roof, windows, bi-fold or sliding doors, insulation to current Building Regulations Part L standards, internal walls and layout.
All second-fix trades — electrics, plumbing, underfloor heating where specified, plastering, tiling, decoration and snagging. Building control sign-off arranged on completion.
Why London Homeowners Choose Covers Of London for House Extensions
London has no shortage of extension builders. What it does have a shortage of is builders who turn up when they say they will, stay on programme, and charge what they quoted.
We have been carrying out building work across the capital for more than thirty years. Our team is made up of tradespeople who work for us directly — they are not agency workers, not sub-contracted labour, and not replaced mid-project with whoever is available. The people who dig your foundations are part of the same operation that plasters your walls and fits your bi-fold doors.
Each project comes with a written fixed-price quotation. The price we agree before the build starts is the price on the final invoice. If anything unexpected arises — drainage issues, ground conditions, unforeseen structural problems — we discuss it with you before any additional cost is committed.
All work carries a 10-year workmanship guarantee. We hold full public liability insurance. And if, after surveying your property, we believe the extension you have in mind is not practical for your site, we will say so. We would rather give you an honest assessment than take your deposit for a job that was never going to work.
Service Areas
House Extensions Across Every London Borough
Based in Hackney, we build house extensions right across London and into the surrounding counties. If your property sits within the M25, we can reach you. We also take on projects in parts of Essex — Chingford, Woodford, Loughton, Romford, Ilford and Brentwood — and across Hertfordshire including Enfield, Cheshunt, Potters Bar, Broxbourne and St Albans. Our knowledge of local housing types, borough-specific planning requirements and building regulations saves time and prevents the kind of problems that catch less locally experienced builders off guard.
Hackney
Islington
Tower Hamlets
Camden
Haringey
Newham
Waltham Forest
Barnet
Enfield
Southwark
Wandsworth
Greenwich
Bromley
Croydon
All London Boroughs →
FAQS
House Extensions — Frequently Asked Questions
How much does a house extension cost in London?
Costs depend on the extension type, size and specification. A single storey rear extension in London typically costs between £50,000 and £80,000. Side return extensions range from £35,000 to £55,000. Wrap around extensions usually cost between £60,000 and £100,000. Double storey extensions start from around £80,000. We carry out a free on-site survey and provide a detailed fixed-price quotation so you know the full cost before work starts.
Do I need planning permission for a house extension?
Many single storey rear extensions fall within permitted development rights. Detached houses can extend up to 4 metres to the rear without planning permission, and terraced or semi-detached properties up to 3 metres. However, properties in conservation areas, those with Article 4 directions, and most double storey extensions will require a full planning application. We check the rules for your specific property and borough and handle all planning submissions as part of our service.
How long does a house extension take to build?
A single storey rear extension typically takes 10 to 14 weeks on site. Wrap around extensions take 12 to 16 weeks. Double storey extensions usually take 16 to 20 weeks. The full project timeline including design, approvals and construction is typically 4 to 7 months from initial consultation to completion.
Can I stay in my house during the extension build?
In most cases, yes. We plan the build sequence to keep disruption to a minimum. The kitchen is usually the last area affected, and there may be a few days when services are disconnected during the knock-through. We discuss the build programme with you in advance and work around your household’s routine wherever we can.
What type of extension is best for a Victorian terraced house?
For Victorian terraces, a side return extension is the most common starting point — it fills in the narrow passage alongside the kitchen and widens the ground floor without reducing garden space. Many homeowners then combine this with a rear extension to create a wrap around, which produces the largest open-plan ground floor area possible. We assess your property during the free survey and recommend the best option for your site, budget and requirements.
What areas do you cover for house extensions?
We are based in Hackney and cover every London borough. We also work across parts of Essex including Chingford, Woodford, Romford and Ilford, and Hertfordshire including Enfield, Cheshunt, Potters Bar and St Albans.
Get a Free House Extension Quote
Whether you need a side return infill or a full wrap around that transforms your ground floor, our survey and quotation service is free and carries no obligation. Leave your details and we will be in touch within the hour during working hours.
Book Your Free House Extension Survey Today
If you have been thinking about extending your home, get in touch. Call us on 0208 064 3801 or fill in the form above and we will arrange a free on-site survey. We will talk you through the options for your property and provide a detailed fixed-price quotation. Most surveys are carried out within a week of your call.