House Extensions in Hillingdon

At Bigness Group, we design and build high-quality house extensions in Hillingdon, helping homeowners across West London unlock new space and elevate their homes.
From family houses in Uxbridge and Hayes to period properties in Ruislip and Northwood, we deliver extensions that combine design excellence, durability, and energy efficiency.

We manage every step — from planning and design to construction and finishing — ensuring your project is handled professionally, transparently, and on schedule.

Design and Build Services

Our Hillingdon design-and-build team provides a complete start-to-finish service:

• Measured surveys and architectural drawings

• Planning and permitted development guidance through Hillingdon Council

• Structural design and Building Control compliance

• Interior layout, kitchen, and lighting integration

• Dedicated project management with clear communication throughout

With Bigness, one expert team handles everything — guaranteeing accountability, consistency, and exceptional results.

Types of Extensions We Build

We construct all major types of house extensions across Hillingdon, including:

• Glass Box Extensions – Contemporary architectural additions.
• Modern House Extensions – Sleek designs that fuse architecture and innovation.
• Single-Storey Extensions – Expand your kitchen, dining, or family area with natural light.
• Double-Storey Extensions – Add bedrooms or offices above while extending living space below.
• Side-Return Extensions – Perfect for semi-detached and terraced homes.
• Rear Extensions – Create spacious, modern garden-facing living areas.
• Wrap-Around Extensions – Combine side and rear builds for full open-plan layouts.
• Conservatories & Orangeries – Glazed extensions for all-season comfort.
• Loft & Garage Conversions with Extensions – Add new rooms vertically or repurpose existing structures.

Construction Standards

Every Bigness project in Hillingdon follows our proven six-step construction process:

1. Groundworks & Foundations – Designed for local soil and property type.

2. Structural Framework – RSJs and beams installed for strong, open layouts.

3. Walls & Roofs – Brick match or rendered finishes with full insulation.

4. Glazing & Energy Systems – Energy-efficient materials meeting current regulations.

5. Interiors & Finishes – Plumbing, electrics, plastering, and joinery.

6. Final Approval & Warranty – Building Control certification and long-term guarantee.

Local Knowledge

We’re experienced with Hillingdon Council’s planning policies and Building Control regulations, including work in conservation areas such as Northwood Hills and Uxbridge Town.
Our understanding of local standards ensures every extension gains approval quickly and complements its surroundings.

Costs and Financing

Every extension is unique, but here’s a general guide:

💡 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.