House Extensions Across London

Add the space you need without moving house. We design and build house extensions across London from compact side returns to substantial double-storey additions. We handle architectural plans, planning permission, building regulations, and complete construction.

London's Most Trusted Construction Partner

20+ Years Delivering Excellence

100+ London Projects Completed

7facebook.png Foundation and Finishing in Greater London
Based on 56 Reviews
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Based on 82 Reviews
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Based on 108 Reviews

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Our Services

Professional Building Services in House Extensions

For over 22 years, Foundation and Finishing has been delivering exceptional House Extensions services across Greater London. Whether you're adding space with a side return, creating an open-plan kitchen-diner, or building a double-storey addition, we handle every detail from planning permission to final completion.

Transform wasted side passage into valuable kitchen or dining space. Popular with Victorian and Edwardian terraced houses, side returns typically add 12-15 square metres without planning permission.

Extend into your back garden to create larger kitchens, dining rooms, or family spaces. We design extensions with bifold or sliding doors, roof lanterns, and underfloor heating.

Combine side return and rear extension for maximum space gain. Creates stunning open-plan kitchen-diners spanning the full width of your property.

Add space on two levels – typically kitchen and dining downstairs with extra bedroom and en-suite above. Requires planning permission but adds significant value.

Transform existing conservatories into permanent year-round living spaces with proper insulation, heating, and structural upgrades.
Purpose-designed extensions focused on creating dream kitchens with dining and living areas. We work with you on layout, appliances, storage, and lighting.
Elegant extensions with brick pillars and substantial glazing creating light-filled garden rooms. More substantial than conservatories with proper insulation and year-round usability.
Extend your entrance with a stylish porch adding character and functionality. Creates welcoming entrance spaces and additional storage.
Modern glazed extensions with floor-to-ceiling windows and skylights creating light-filled spaces. Contemporary designs perfect for contemporary homes.

Why Families Choose Us

20+ Years, Results
That Speak for
Themselves

Over 100 London families trusted us with their biggest investment. The kind of work that makes homeowners call us back for their next property.

You Decide Everything, We Handle Everything

Over 100 London families trusted us with their biggest investment. The kind of work that makes homeowners call us back for their next property.

Group 2661 Foundation and Finishing in Greater London

Work That Actually Gets Done On Time

Over 100 London families trusted us with their biggest investment. The kind of work that makes homeowners call us back for their next property.

Same Team From Quote to Completion

We work with the same qualified tradespeople on every job. Gas engineers, electricians, builders, finishers. They know our standards and they deliver. One point of contact for you, zero coordination headaches.

Honest Communication

We give you realistic timelines and pricing up front. If we discover something unexpected during the work, you know immediately. No hiding problems until it's too late.

Group 2661 Foundation and Finishing in Greater London

20+ Years, Results
That Speak for
Themselves

Over 100 London families trusted us with their biggest investment. The kind of work that makes homeowners call us back for their next property.

You Decide Everything, We Handle Everything

Over 100 London families trusted us with their biggest investment. The kind of work that makes homeowners call us back for their next property.

Same Team From Quote to Completion

We work with the same qualified tradespeople on every job. Gas engineers, electricians, builders, finishers. They know our standards and they deliver. One point of contact for you, zero coordination headaches.

Honest Communication

We give you realistic timelines and pricing up front. If we discover something unexpected during the work, you know immediately. No hiding problems until it's too late.

Work That Actually Gets Done On Time

Over 100 London families trusted us with their biggest investment. The kind of work that makes homeowners call us back for their next property.

icon Trusted Construction Services
icon Quality Craftsmanship & Reliability
icon Strong Foundations, Lasting Results
icon Professional & Committed Team
icon Trusted Construction Services
icon Quality Craftsmanship & Reliability
icon Strong Foundations, Lasting Results
icon Professional & Committed Team

Our Process

Simple. Straightforward. No Surprises.

Here’s exactly how we handle every project, from start to finish.

Get In Touch

Here's exactly how we handle every project, from start to finish.

We Listen & Advise

We measure everything, talk through your vision, and tell you what will actually work in your space.

Clear Quote

Fixed price. Fixed timeline. No surprises halfway through your project.

We Build It

Same team from day one to completion. Weekly progress photos. Direct line to Fares whenever you need answers.

Frequently Asked Questions

Many extensions fall under permitted development rights and don't need planning permission. We assess your property during consultation and advise whether permission is required.

Single-storey extensions typically take 10-14 weeks from start to completion. Double-storey extensions take 14-18 weeks. Timelines depend on size and complexity.

Most families stay in their homes during extensions. We make properties secure each evening and work is contained to the extension area until final connection.

We handle design, structural calculations, planning applications if needed, building control, and complete construction. You get one point of contact managing everything.

F&F doesn't automatically handle party wall agreements. This is up to the customer to decide whether to use F&F or their own Party wall surveyor of their chocie.

Book Your FREE Home-Visit and Consultation