We are extension builders working on rear, side return, wrap around and double storey projects across South London and North Kent. Since 2012 we have handled everything from compact single storey additions to full-width open plan spaces — structural design, building control sign-off, groundworks and finishing on one programme. The same team stays on the job from the first dig to the final coat of paint, so nothing gets lost in a handover between trades.
An extension is structural work first and a room second. Most of what decides whether the finished space actually works — how much daylight reaches the middle of the room, the ceiling height, the way the new opening meets the existing house — is settled on paper long before anyone chooses a floor finish.
We start with a measured survey of the existing structure, then work through the approvals route with you: permitted development where it applies, a full planning application where it does not, and building regulations either way. Once approved, we handle groundworks and foundations, drainage diversions, structural steel, brickwork, the roof, glazing, and first and second fix across every trade.
Because our carpentry, kitchen fitting and flooring teams are in-house, the finishing stages run without the delays that come from booking each trade separately. Most house extension builders subcontract that final third of the job. We do not, which is why our programmes hold.
Which option suits your house depends on the plot, the existing layout and what you are trying to gain. We will tell you honestly which of these makes sense before any design work starts.
The most common project we take on. A single storey extension typically runs three to six metres back from the existing rear wall, and is most often used to open a cramped kitchen into a dining or family space. How far you can go, and whether you need planning permission, depends on whether the house is detached and how close you are building to the boundary.
Adds space at ground and first floor in one build, which works out considerably cheaper per square metre than doing two separate projects. A double storey extension almost always needs full planning permission, and it takes closer attention to detail — the new roofline and brickwork have to tie into the existing house convincingly, or the result looks bolted on.
Fills the narrow alley running alongside the back of a Victorian or Edwardian terrace. A side return extension rarely adds a large footprint, but it transforms how the ground floor works — a dark galley kitchen becomes a full-width room. Extremely common across South London’s terraced streets, and often combined with a rear extension.
Combines a rear extension with a side return in a single build, forming an L around the back of the house. It is the largest of the single storey options and the one that changes a floor plan most dramatically. The structural design needs care where the two elements meet, particularly at the corner.
In practice, most rear extensions are kitchen extensions. We coordinate the structural build with the kitchen installation directly, which means the plumbing and electrics are in the right positions before plastering rather than being chased into finished walls afterwards. See our kitchen installation page for how that side of the work is handled.
Removing a load-bearing wall to open two rooms into one, with the steel beam, padstones and building control sign-off all handled. Often done alongside an extension, sometimes as a project on its own.
Extensions go wrong in predictable ways, and most of them trace back to decisions made before anyone arrives on site. This is the order we work in.
Extensions fail in three predictable ways: the structural design is undercooked, the programme slips because trades are booked separately, or the quotation leaves out work that was always going to be necessary.
We survey before quoting, so the figure you receive already accounts for foundation depth, drainage and steel rather than treating them as extras discovered halfway through. The trades that finish the build are our own, so the last six weeks of a project — where delays usually pile up — run to the same programme as the first six. And you deal with one point of contact from the survey to the handover.
That is the difference between us and most home extension builders working at this scale: we are accountable for the whole thing, not just the part that gets photographed.
Balham, Clapham, Brixton, Streatham, Tooting, Wimbledon, Mitcham, Worcester Park
Gravesend, Northfleet, Dartford, Meopham, Higham, Shorne, Cobham, Ebbsfleet
Based in Balham SW12 and working across South London and North Kent.
Not sure if we cover you?
Call 07472 137237 and ask.
Two extensions with identical floor areas can differ substantially in price, which is why we do not publish a rate per square metre. These are the things that actually move the house extension cost up or down:
We quote in writing after a site visit, itemised by stage, so you can compare it properly against anyone else’s.
Tell us what you are planning and we will arrange a site visit. No obligation, no pressure, and a written quotation you can compare.
Detailed insights into our operational standards, project management philosophy, and technical capabilities.
Often not. Many single storey rear extensions fall under permitted development, which means no full planning application is needed. As a general rule a single storey rear extension can project three metres from the original rear wall on a terraced or semi-detached house, or four metres on a detached house. Larger projections — up to six and eight metres respectively — may be possible through the prior approval process, which involves consulting your neighbours. Flats and maisonettes have no permitted development rights at all, and conservation areas and listed buildings are treated differently. We confirm which route applies to your property at the survey stage, before any design work begins.
For a single storey rear extension the standard permitted development limits are three metres beyond the original rear wall for an attached house and four metres for a detached house, with a maximum height of four metres. If the extension comes within two metres of a boundary, the eaves height is capped at three metres. A two storey rear extension must not project more than three metres and must sit at least seven metres from the rear boundary. Extensions also must not cover more than half the land around the original house. These are the headline figures; we check your specific property against them at survey.
A straightforward single storey rear extension usually takes twelve to sixteen weeks on site once work starts. Double storey and wrap around builds typically run sixteen to twenty four weeks. Design, planning and building control approval all happen before that and can add eight to sixteen weeks depending on which route your project takes. We give you a stage-by-stage programme with the quotation so you know what to expect and when.
Most of our clients do. We seal the working area off from the rest of the house, agree access and working hours with you in advance, and sequence the work so kitchen and bathroom facilities stay available for as long as possible. Where a period without a kitchen is unavoidable, we tell you at programme stage how long it will be so you can plan around it rather than finding out on the day.
Yes, and they are two separate things that people often confuse. Planning permission is about whether you are allowed to build it. Building regulations are about whether it is built safely and to standard, covering structure, insulation, ventilation, drainage and fire safety. An extension needs building regulations approval even when it falls under permitted development and needs no planning application at all. We handle the building control submission and inspections as part of the job.
If the work involves excavating close to a shared boundary or building off a party wall, you will usually need to serve notice on the affected neighbours under the Party Wall Act. This is separate from both planning permission and building regulations. We flag it at survey stage and can point you towards a party wall surveyor. It is worth starting early, because notice periods can add a month or two to the timeline.
Usually, though how much depends on the property, the local market and whether the extension genuinely improves the layout rather than simply adding floor area. An extension that leaves the middle of the house dark, or produces an awkward plan, can add less than it cost to build. This is why we spend time on the design stage and will tell you if we think a scheme is not worth doing as drawn.
Yes. We manage the approvals route from the survey onwards, whether that means a certificate of lawful development, a full planning application or the prior approval process, along with the building regulations package and the building control inspections during the build.
