Double Storey Extensions

About our double storey extensions service

A double-storey extension represents one of the most effective ways to transform a property without the need to relocate. Unlike standard House Extensions that only address ground-floor needs, these projects allow for a wholesale rethink of how a home functions. They are ideal for growing families who require additional bedrooms or master suites on the first floor alongside expanded kitchen or dining areas below. For commercial landlords, two-storey additions can also be used to increase the capacity of HMOs or multi-unit dwellings. While more complex than Rear Extensions or Side Extensions, the dual-level approach offers a much better ratio of cost-to-space. These projects require precise structural engineering to support the upper floor weight and careful consideration of the existing foundations. At Design N Build, we manage the entire process, including the integration of M&E services and ensuring the new structure blends perfectly with the original character of your building.

What's included

• Architectural Planning

  Full management of the planning process, including architectural drawings and submission to local authorities for two-storey approvals.

• Building Regulations Compliance

  We handle all building control inspections and ensure the new structure meets the latest thermal and fire safety regulations.

• Groundworks & Foundations landscapes

  Comprehensive groundworks, including reinforced foundations and drainage alterations needed to support a taller, heavier structure.

• M&E Integration

  Professional installation of all plumbing, heating, and electrical systems, ensuring the upper floor has consistent pressure and power.

• Interior Fit-Out

  Skilled trades for all internal works, from tiling en-suites to installing bespoke cabinetry and decorative finishes.

Key benefits

• Maximise Land Footprint

  By adding floor space over two levels, you essentially double the square footage of your home without significantly impacting the footprint of your garden or outdoor areas.

• Cost-Efficiency

  Adding two floors at once is more cost-effective per square metre than building two separate single-storey additions, as groundworks and roofing costs are shared across both levels.

• Substantial Value Increase

  Increasing the bedroom count and ground floor living area simultaneously creates a significant uplift in market value, often providing a stronger return on investment than smaller projects.

• Internal Layout Flexibility

  Two-storey builds allow for total reorganisation of your home, including moving staircases or adding en-suites, rather than simply tacking on a single isolated room.

• Enhanced Curb Appeal

  A full-height addition offers the opportunity to redesign the exterior aesthetic of your property, giving an older house a modern, cohesive architectural look.

Project types we cover

• Residential Family Homes
• Terraced & Semi-Detached Houses
• Commercial Property Portfolios
• Master Suite Additions
• Open-Plan Kitchen & Bedroom Combos
• HMO Expansions

Our process

1. 1
   Initial Consultation

   Our surveyors and designers assess your property to determine structural feasibility and help you define a realistic budget for the project.

2. 2
   Detailed Design & Planning

   Detailed drawings are produced for planning applications and building control. We ensure the designs meet local authority guidelines while maximising your available space.

3. 3
   Structural Engineering

   Our engineers calculate the necessary steel reinforcements and foundation depths required to safely support the additional weight of a second floor.

4. 4
   Construction Phase

   Our site teams manage the excavation, wall construction, and roofing. We coordinate the first-fix electrics and plumbing to ensure the new levels integrate with existing systems.

5. 5
   Finishing & Handover

   After the shell is complete, we handle plastering, flooring, and joinery. A final inspection ensures everything meets our quality standards before we hand over the keys.

Why choose Design N Build Construction Company

• End-to-End Management

  We offer a complete service from the first drawing to the final coat of paint, reducing the stress of managing multiple contractors.

• Technical Expertise

  Our builders and engineers have extensive experience in multi-level construction, ensuring your extension is structurally sound and durable.

• Transparent Pricing

  We provide clear, detailed quotes without hidden costs, helping you manage your finances effectively throughout the build.

• Quality Workmanship

  We treat your property with respect, maintaining a clean site and ensuring all work meets rigorous safety and quality standards.

• Reliable Timelines

  We understand the importance of sticking to a schedule, especially when a project affects both floors of your home.

Frequently asked questions

Talk to us about your project

Choosing to extend across two storeys is a significant investment that requires careful structural planning and a clear understanding of building regulations. At Design N Build, we help homeowners and developers navigate the complexities of large-scale additions, from the initial feasibility study through to the final interior finishes. Whether you are looking to add master suites, home offices, or expansive open-plan kitchens, our team provides the technical expertise to ensure your project is completed safely and to a high standard. Contact our consultants today to discuss your site requirements, budget expectations, and how a double-storey extension can best serve your long-term property goals.