Single and double storey extensions in Old Street. Trusted, professional, 30+ years' hands-on experience.
Extension work in Old Street looks different from the terraced-street norm. Around EC1, GS Renovation works on warehouse conversions, new-build apartments and the occasional period house near Clerkenwell and Highbury. With 30+ years extending North London homes, we handle foundations, steelwork, roofing and fit-out, and we are honest about what Islington Council will and will not allow on a given building.

Where a genuine house survives on the streets between Old Street and Clerkenwell, a rear or side-return extension can transform a cramped ground floor into an open-plan kitchen-diner. We dig and pour foundations sized to the ground conditions, install the steel beams that carry the existing rear wall, and tie the new roof into the old. Every opening is designed by a structural engineer and inspected under building regulations.
Whether the work is permitted development or needs a full planning application depends entirely on the property. A modest single-storey rear extension may fall under permitted development, but conservation area status, a flat above or previous additions can remove those rights and require permission from Islington Council. We assess your title and location first, then submit the right application rather than guessing and risking enforcement.
Most Old Street homes are flats, and extending a flat is a different discipline. Outward expansion is usually impossible, so we focus on what leasehold allows: enclosing a balcony, reconfiguring internal volume, or adding a mezzanine where a converted warehouse offers the ceiling height. Each option depends on the lease, the freeholder's licence to alter and the structural capacity of the existing floor, which our engineer confirms.
Any external change to a new-build or conversion in EC1 typically needs both the freeholder's consent and, where it alters the building's appearance, planning permission from Islington Council. We coordinate with the managing agent on access, working hours and protection of common parts, and we keep neighbouring leaseholders informed. The building regulations side, from structure to insulation and fire separation, is handled and signed off as part of the job.
An Old Street extension is as much a permissions puzzle as a building one. GS Renovation reads the lease, the planning position and the structure together, then delivers foundations, steel, roof and fit-out with one accountable team. Three decades in EC1 and across Islington mean fewer surprises, cleaner approvals and a finish that suits these conversions and new-builds.
George was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great attention to detail. I've already recommended him to others.
Splendid job on our new kitchen refurb, including new flooring, moving the services, installing RSJ and preparing space for new back doors… George was always friendly, communicative and has an excellent attention to detail, ensuring everything is finished to a high standard.
Giorgio is an excellent and intelligent workman, and with very reasonable prices!… He paid a lot of attention to detail that is not common at all, and the final result was immaculate. Highly recommended!
FAQ
Pricing house extensions in Old Street comes down to the size of the job, the specification you choose and the condition of the property. Rather than guess, we survey and give you a fixed, itemised quote you can rely on. Call 07472 424 226. As a rough guide, house extensions in London typically starts from roughly £40,000 for a single-storey rear extension and rises with size and specification (indicative London ranges, MyBuilder and Checkatrade, 2026). Your figure depends on the size, specification and condition of the property, which is why we survey before quoting.
Most house extensions projects in Old Street take between two and eight weeks depending on the scope and whether structural work is involved. We provide a clear programme before work begins so you know exactly what to expect.
Old Street homeowners choose GS Renovation for reliability and quality. We are fully insured, building control compliant where needed, and bring over 30 years of hands-on experience to every house extensions project, with a single point of contact throughout.
Many single-storey rear extensions in Old Street fall under permitted development, but side returns, double-storey extensions and work in conservation areas usually need full planning permission. We assess your property and manage both the planning application and building control.
Yes. A large share of Old Street's homes are warehouse-conversion and new-build properties, and we renovate them regularly. We plan each house extensions around their particular characteristics, such as concrete or steel frames, building-management rules and modern services, so the result suits the building and meets building control.
Sometimes, but the options differ from a house. Outward extension is rarely possible, so we look at enclosing balconies, reconfiguring space or adding a mezzanine where ceiling height allows. Any change needs the freeholder's licence to alter, and external alterations may need planning permission from Islington Council. We check the lease and structure first, then advise honestly on what is achievable.
We do. GS Renovation covers all of Old Street and the EC1 area and the wider North London. Call 07472 424 226 and we will confirm we work on your road.
Every Service, One Team
The same trusted team, 30+ years' hands-on experience and free, no-obligation quotes apply to every GS Renovation service in Old Street. Explore what else we do locally:
Steel beam installation, RSJ and structural alterations.
Safe load-bearing wall removal with steel beam support.
Structural alterations, new openings and steel support.
Chimney breast removal with gallows bracket or beam support.
Open-plan kitchen, diner and living conversions.
Full refurbishments and whole-house renovations.
Bespoke kitchen design and installation.
Luxury bathroom and wet-room refurbishment.
Same Service, Nearby Areas
We carry out house extensions across Old Street and the surrounding areas. Explore a nearby location:
Contact GS Renovation today for a free, no-obligation quote for house extensions in Old Street.
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