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House Extensions

Side-return, rear and double-storey extensions engineered specifically for North London's period properties — planned around your home's existing structure, not against it.

House Extensions by GML Construction in North London

Extensions built for period homes, not generic new-builds

Most extension companies in London work from standard templates. We don't — the majority of our work is on Victorian and Edwardian properties across Hampstead, Highgate and the surrounding streets, and every one of those buildings has its own quirks: party wall considerations, original brick that needs matching, foundations that weren't built with modern extensions in mind.

We plan every extension around the property as it actually is, not as a standard drawing assumes it to be. That means fewer surprises once work starts, and a finished extension that looks like it belongs on the house rather than bolted onto it.

What we cover

  • Side-return extensions — reclaiming the alley space beside Victorian terraces
  • Rear extensions — single and double-storey
  • Wrap-around extensions combining side and rear
  • Structural steel and load-bearing wall removal, engineer-signed
  • Full internal fit-out once the shell is complete — we don't hand this off to a separate team

Planning permission & party wall matters

Many extensions in this part of London fall under Permitted Development rights, but not all — particularly on second-storey additions or properties in conservation areas, which cover large parts of Hampstead and Highgate. We'll tell you honestly at the quote stage whether planning permission is likely to be needed, and can point you toward the right party wall surveyor if neighbouring agreements are required.

Types of house extension we build

Whether you're looking to add a room, extend upwards or transform unused space, we have the expertise to bring your vision to life.

  • Single storey extensions — ideal for expanding a kitchen, adding a dining area or creating a utility room or home office, typically to the rear or side.
  • Double storey extensions — considerable extra living space, built at the back or side of the house.
  • Over-structure extensions — built over existing structures such as garages, extending the first floor while preserving garden space.
  • Rear extensions — extending onto your garden or courtyard, ideal for larger open living spaces.
  • Side return extensions — turning unused alleyway space into valuable living area.
  • Wraparound extensions — side return and rear combined into an L-shape for substantial open-plan layouts.
  • Conservatory extensions — glass-built extensions, versatile for entertaining or as a sunroom.
  • Orangeries — brick pillars with raised glass roofs, combining extension and conservatory styles.
  • Garden room extensions — detached garden buildings suitable for offices, music rooms or studios.
  • Porch extensions — simple and stylish, improving the front of the property, security and storage.

Seamless integration

Our goal is to create extensions that read as a natural part of your home, maintaining architectural harmony and increasing your property's value.

01

Site Visit & Quote

Free, no-obligation assessment and a fixed written quote.

02

Design & Planning

Drawings and planning guidance where needed, before anything starts.

03

Build

One site manager, our own trades, start to finish.

04

Handover

Final walkthrough and snagging before we call it done.

Our extension work

House extension work photographed during construction, including brickwork, roof framing and glazing installation.

Brick house extension with exposed roof timbers and glazing during construction
Timber-framed window fitted into new extension brickwork
Exterior view of a timber-framed upper window and new extension brickwork
Sliding glazed doors installed in a brick extension under construction
Front view of a dark-clad extension with full-height glazing during construction
Side view of full-height extension glazing and exterior cladding
Wide exterior view of a dark-clad glazed extension with landscaping unfinished

Common questions

How long does a typical extension take?

A single-storey rear extension usually runs 8–12 weeks once work starts; larger or double-storey projects can run longer. We'll give you a realistic timeline specific to your project at quote stage, not a generic estimate.

Do you handle planning applications?

We can guide you through what's needed and work alongside an architect or planning consultant where required. For straightforward Permitted Development projects, we can often advise directly.

Will the extension match the existing brickwork?

Matching original brick and period detailing is something we take seriously, particularly on conservation-area properties — we source matching or reclaimed materials wherever possible.

Related Services

  • Loft Conversions
  • Structural Works
  • Kitchen Installs
  • Home Refurbishments

Thinking about an extension? Let's talk it through.