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HomeBuilding Services

House Extensions (Non-Kitchen) – Side, Rear & Double-Storey

House Extensions in London – Side, Rear & Double-Storey

A well-designed extension can transform a London home, adding valuable space for living, working and relaxing. While we have a dedicated section for kitchen-led extensions, many projects focus on extra living rooms, home offices, bedrooms or bathrooms. This page covers non-kitchen house extensions in London – including side returns, rear additions and double-storey extensions – and explains how we approach structure, drainage, glazing and finishes so that new space feels like a natural part of your home.

Bespoke Conversions has built extensions throughout South West, South East and West London for over 20 years. We work with your architect or designer to turn their drawings into reality, focusing on clear communication and tidy, well-sequenced work on site. Whether you are planning a modest side return extension to open up the ground floor, a larger rear extension for more family space, or a single-storey extension to provide a new home office or studio, our role is to execute the build safely and to a high standard.

Because extensions inevitably touch on structure, drainage, roofing, glazing and external finishes, this page links closely with our structural alterations and RSJ beams, roofing and roof repairs, windows, doors and glazing and rendering and external wall finishes content, which provide more detail on those specialties.

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Types of House Extension

Common house extensions in London include:

  • Side return extensions – using the narrow passage beside a terrace or semi-detached house to widen internal rooms.
  • Rear extensions – projecting into the garden to create larger living areas or new rooms.
  • Single-storey extensions – often used for family rooms, studies or ground-floor bedrooms.
  • Double-storey extensions – adding rooms at both ground and first-floor level, frequently to increase bedroom and bathroom space.

Many properties combine these forms, for example blending a side return extension with a modest rear projection to create an L-shaped footprint. Your architect will typically advise on massing, roof form and glazing strategy; we then build to those specifications.

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Planning Permission and Permitted Development

Some house extensions in London can be carried out under permitted development rights; others require full planning permission. Factors include:

  • Property type (house vs flat or maisonette).
  • Location (e.g. conservation area, Article 4 direction).
  • Extension size, height and proximity to boundaries.
  • Design elements such as roof form and materials.

We do not submit planning applications ourselves, but we regularly work with schemes already approved and can recommend architects and planning consultants where you do not yet have professional support. For more background, our planning permission for extensions and loft conversion planning pages outline key rules and considerations.

Structure, Foundations and Drainage

A successful house extension in London rests – literally – on good foundations and appropriate structure. Depending on ground conditions and design, this may involve:

  • Traditional strip foundations.
  • Trench-fill or raft solutions in more challenging soils.
  • Piled foundations where necessary, particularly on restricted access or sensitive sites.

New walls, beams and roofs are sized by structural engineers, whose calculations inform our construction. Drainage is also critical: we plan connections into existing systems, consider gradients and access for maintenance, and ensure that gullies, downpipes and surface water management are properly detailed. These elements may link with our roofing and roof repairs and damp proofing content where waterproofing and moisture control are important.

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Glazing Strategy and Natural Light

Well-placed glazing makes rear extensions and side return extensions feel bright and welcoming rather than dark and tunnel-like. We often install:

  • Large sliding or bi-fold doors to gardens.
  • Rooflights, lanterns or slot windows to pull light into deeper plan areas.
  • High-level windows to maintain privacy while bringing in daylight.

The exact approach will depend on orientation, overlooking, privacy and overheating considerations. We work closely with your designer and our windows, doors and glazing specialists to deliver openings that meet performance standards as well as aesthetic goals.

Envelope Performance – Insulation and Air-Tightness

Modern house extensions in London must meet current standards for insulation and energy performance. We construct walls, roofs and floors with appropriate insulation thicknesses and pay attention to:

  • Continuity of insulation at junctions.
  • Air-tightness around windows, doors and service penetrations.
  • Ventilation strategies to keep air quality high.

These details, combined with efficient heating via our plumbing and heating services, help ensure that your new space is comfortable and economical to run.

Interiors, Finishes and Integration

Internally, a good extension should feel like a natural continuation of the home. That includes:

  • Floor levels and coverings that blend old and new.
  • Consistent skirting, architraves and door styles, coordinated with our carpentry and joinery services.
  • Smooth transitions in wall finishes and colours, delivered via our painting and decorating team.

We can also coordinate built-in storage, media walls and other joinery so that your new rooms are as practical as they are attractive.

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Double-Storey Extensions – Extra Bedrooms and Bathrooms

A double-storey extension can significantly increase usable space by adding both living areas and upstairs rooms. Typical uses for the upper level include:

  • Additional bedrooms.
  • Family bathrooms or en-suites.
  • Home offices away from the busiest parts of the house.

In these projects, careful consideration of privacy, overlooking, roof form and structural loading is crucial. Building control and planning expectations can be more stringent, and your engineer will play a central role. We then deliver the build, tying in with our loft conversion and structural alterations experience where relevant.

FAQs – House Extensions in London

How long does a typical extension build take?

A straightforward single-storey house extension in London might take from three to four months on site, depending on specification, weather and access. Double-storey extensions and projects combined with internal refurbishment can take longer. Your architect and builder should give you a project-specific programme.

Can I live in the house while the extension is built?

In many cases yes, although there will be noise, dust and temporary disruption. We discuss phasing, protection and temporary arrangements at the outset. For major house extensions in London combined with full refurbishments, some clients choose to move out for part of the work.

Do I always need planning permission?

Not always. Certain side return extensions and rear extensions may be possible under permitted development, depending on size, height and previous works. Your architect or planning consultant will confirm this for your property, and we will then build in line with the approved drawings.

Will an extension add value to my home?

In most London areas, well-designed house extensions in London that create extra living, bedroom or bathroom space are attractive to buyers. Exact value uplift will depend on your location, specification and the balance of house and garden after the extension.

Can you also handle interiors and finishes?

Yes. As well as the structural shell, we can coordinate internal works, including plastering, joinery, decorating and flooring, with dedicated pages for carpentry and joinery, flooring and tiling and painting and decorating explaining these services in more detail.

Customer Feedback

Builders were very clean and polite- always tidied up after themselves, good communication between all parties, work done to a very high spec and very happy with the job. Wouldn’t hesitate to recommend them to others

The workers were great-knowledgeable, courteous and very efficient. They finished on time and I am very satisfied.

Loft conversion

Very experienced builders with first class work at every stage of our loft build. Always felt very confident of their ability to deal with all aspects of the work and deal with any unforeseen problems.

Renovation of ground floor. Opening back of house, new kitchen, new bathroom

Outstanding standard of work, complete attention to detail. Always listened and worked with us. The team are extremely professional and always willing to go the extra mile. We love the final result.

Whole house restoration

Would highly recommend Shane and his builders. Work was to a high standard and they couldn’t have been more helpful. Nothing was too much trouble.

Extension, new kitchen and bathroom

We are delighted with the extension along with the new bathroom and kitchen. It’s turned our small flat into a lovely family home.

Full house renovation

The level of craftsmanship from Shane and the team is second to none. They have completed a full house renovation during a country wide epidemic in a throughly professional manner. If you want the best team in London call these guys. You won’t be disappointed.

Kitchen and diner knocked into one, new kitchen fitted

Great input at the beginning with different options. Good recommendation for a window company to do the double glazing. Work was completed on time and to a great standard. Aesthetics were carefully considered and the process was very black and white. Good comms, emails and phone calls always answered.

Kitchen diner conversion

Shane and his team are great, workmanship is top notch, super tidy, on time on budget. Second time I’ve used them now – highly recommended!

Loft conversion/2 bedrooms and en-suite.

Builders were very clean and polite- always tidied up after themselves, good communication between all parties, work done to a very high spec and very happy with the job. Wouldn’t hesitate to recommend them to others.

Contact us now to get a free quote and learn more about our wider building services in Clapham and across South London.

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