The Smart Solution for Extensions · All 32 London boroughs

Extensions in London

Single and double-storey, rear, side-return and wrap-around extensions — from foundations to final decoration.

Rear extension, 1930s semi

What we do

From the installation of steel beams and waste pipes to double glazing, we build extensions that clear building control first time. Most London extensions live or die on two questions asked early: does it fall under permitted development or need a full application, and is a Party Wall Award required. We answer both before you commit, in writing.

Included as standard

Feasibility check: permitted development vs. full planning
Architectural drawings and planning submission
Structural engineer's calculations and building control
Party Wall Act notices, surveys and awards
Foundations, drainage diversion and groundworks
Brickwork matched to existing, steelwork and roofing
Double glazing, bi-folds and rooflights
Electrics, plumbing, heating and underfloor heating
Plastering, screeding, flooring and decoration
Building control sign-off and completion certificate

Typical timescale: 8–16 weeks on site
Coverage: 32 boroughs
Payment: In arrears
Trading since: 2008

Planning and building control for extensions

A single-storey rear extension can often be built under permitted development rather than a full planning application: up to 3m deep on a terraced or semi-detached house, or 4m on a detached one, with a maximum height of 4m. Where it sits within two metres of a boundary, the eaves cannot exceed 3m.

The Larger Home Extension scheme doubles those depths — to 6m and 8m — but it is not automatic. It requires a prior approval application, and the council notifies your adjoining neighbours; if one objects within the consultation period, the council decides on the impact to their amenity.

Permitted development rights do not apply to flats or maisonettes at all, and they are removed or restricted in conservation areas and wherever an Article 4 direction is in force. That is the first thing we check, because it changes both the programme and the cost.

Whichever route the permission takes, the build itself is governed by the Building Regulations — Part A for structure, Part L for insulation and airtightness, and Part K where stairs or level changes are involved. Building control inspects at set stages, including before foundations are covered.

The limits above are the national permitted-development rules for England. Your borough may restrict them further through a conservation area or an Article 4 direction — we confirm the position for your address in writing before quoting.

Our work

Extensions we have completed

Single-storey rear extension on a 1930s semi-detached house with French doors — Rear extension, 1930s semi

Completed interior after refurbishment — Interior, completed

Rear extension and loft conversion in London stock brick with French doors, North Finchley — Extension + loft, North Finchley

Rendered single-storey rear extension with French doors onto a paved patio — Rear extension, rendered

Answers

Extensions — common questions

Do I need planning permission for extensions in London?

It depends on the property type and what is proposed. Many single-storey rear extensions and loft conversions fall under permitted development, but those rights do not apply to flats and are restricted in conservation areas or where an Article 4 direction applies. We check the planning position for your specific address before quoting, and tell you in writing which route applies.

How do you price the work?

From a site survey, written up as a fixed and itemised scope before any deposit is discussed. If something genuinely unforeseen appears once work is opened up, it is priced and agreed in writing before we continue — never added to the final invoice after the fact.

When do I pay?

In arrears of work completed. You pay for work that has been done and inspected, not for work that has been promised. This has been how the company operates since 2008.

Do you handle Party Wall notices?

Yes, where the work requires them. Under the Party Wall etc. Act 1996, notifiable work on a shared wall needs 2 months written notice to the adjoining owner, while excavation near a neighbouring structure and building at the line of junction need 1 month. We serve the notices and manage the award process as part of the job.

Will I get certificates at the end?

Yes. Electrical work is tested and certificated under Part P, and building control issues a completion certificate where an application was required. You receive the handover pack — it is what a buyer's solicitor will ask for when you eventually sell.

How long will it take?

It depends entirely on scope, and we give a programme with the written quote rather than a guess on the phone. What we will not do is start a job we cannot resource, which is the usual reason a build stalls halfway through.

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