House Extensions in Lambeth
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At Bigness Group, we specialise in premium house extensions in Lambeth, transforming homes across South London with design excellence and construction precision.
From Victorian terraces in Clapham and Brixton to townhouses in Kennington and detached homes in Streatham, our bespoke extensions bring light, space, and value — built to modern standards with timeless appeal.
We handle everything — from initial design and planning permission to structural engineering, interiors, and build — ensuring a seamless, stress-free process from start to finish.
Design and Build Services
Our Lambeth design-and-build team offers a complete turnkey service:
Full measured survey and architectural design
Planning and permitted development management with Lambeth Council
Structural calculations and Building Control compliance
Interior layout, kitchen, and lighting design
Dedicated project management with milestone tracking
With one experienced team overseeing every detail, we guarantee quality, accountability, and on-time delivery for every project.
Types of Extensions We Build
We deliver all major types of house extensions in Lambeth, including:
• Glass Box Extensions – Architectural statements for contemporary homes.
• Modern House Extensions – Minimalist designs for a contemporary aesthetic.
• Single-Storey Extensions – Ideal for kitchens and open-plan living spaces.
• Double-Storey Extensions – Add bedrooms, bathrooms, or studies above ground level.
• Side-Return Extensions – Perfect for terraced homes in Clapham, Brixton, and Stockwell.
• Rear Extensions – Combine side and rear expansion for ultimate space.
• Wrap-Around Extensions – Combine side and rear layouts for a seamless flow.
• Conservatories & Orangeries – Elegant glazed rooms for year-round comfort.
• Loft & Garage Conversions with Extensions – Expand upwards or re-purpose existing structures.
• Basement Extensions – Create gyms, cinemas, or private lounges below ground.
Construction Standards
Each Bigness project in Lambeth follows our rigorous six-phase build framework:
Groundworks & Foundations – Engineered for South London’s clay soil conditions.
Structural Steelwork – RSJs and frames installed for stability and open layouts.
Walls & Roofing – Brick match, render, or cladding with warm-roof insulation.
Windows & Glazing – Energy-efficient materials meeting Part L regulations.
Interior Finishes – Electrical, plumbing, flooring, and carpentry work to specification.
Final Certification & Warranty – Building Control sign-off and workmanship guarantee.
Local Knowledge
We are highly familiar with Lambeth Council’s planning and conservation requirements, including areas such as Clapham Park, Herne Hill, and Kennington.
Our expertise ensures your extension gains swift approval and complements Lambeth’s architectural character — from heritage terraces to modern urban homes.
Costs and Financing
Every extension is unique, but here’s a general guide:
| Type | Typical Cost Range (2025) |
|---|---|
| Single-Storey Extension | £45,000 – £85,000 |
| Double-Storey Extension | £75,000 – £130,000 |
| Wrap-Around Extension | £90,000 – £160,000 |
| Side-Return Extension | £40,000 – £75,000 |
💡 Factors include size, materials, access, and specification level.
We provide transparent quotes with detailed breakdowns and stage payments.
Financing options may be available through our partner lenders for eligible clients — ask our team for guidance on home improvement financing.
The Process
1. Consultation & Site Visit – We meet you on-site to discuss ideas, goals, and feasibility.
2. Design & Planning – We prepare drawings, handle permissions, and finalise the budget.
3. Construction Phase – Our project manager oversees all work, ensuring safety and communication at every step.
4. Completion & Aftercare – Once finished, we conduct final inspections and provide warranty documentation.
We also offer optional maintenance plans to keep your new space performing at its best.
Why Choose Bigness Group
Local expertise: deep knowledge of Lambeth’s housing and planning policies.
Complete service: design, planning, construction, and interiors managed in-house.
Certified professionals: compliant with UK Building Regulations.
Transparent pricing: fixed, itemised quotes and milestone billing.
Proven track record: trusted by homeowners across South London.
With Bigness Group, your extension is built with precision, integrity, and a clear vision — designed to elevate both your home and your lifestyle.
FAQ
Do I need planning permission for an extension in Lambeth?
Many small extensions fall under permitted development, but listed or conservation properties require planning. We handle all submissions and liaison with the council.
How long does construction take?
Average build time is 8–14 weeks for single-storey and 12–20 weeks for larger or two-storey extensions.
Do you handle interior design and kitchens?
Yes — our in-house team integrates interior design, kitchen fitting, and lighting layouts.
Can you work in conservation areas?
Absolutely. We’re experienced in managing planning permissions for Lambeth’s conservation zones.
Our Recent Projects in Lambeth
Recent Bigness builds include a double-storey family extension in Clapham, a rear kitchen build in Brixton Hill, and a glass box addition in Streatham.
Each reflects our precision, craftsmanship, and design integrity — hallmarks of the Bigness Group standard.
Practical thinking for better-managed buildings.
Guidance, technical insight and practical perspectives on compliance, maintenance, building performance and long-term improvement.
