Key Takeaway
How much does a two-storey extension cost? Hampshire 2025 pricing: £70,000-£150,000 for typical projects. Build costs £1,600-£2,800/m², structural requirements, and design fees explained. Get your free estimate.
Two-Storey Extension Cost Hampshire 2025: The Complete Guide
A two-storey extension offers the best value for money in terms of cost per square metre, providing additional ground floor living space plus an extra bedroom or bathroom above. Use our extension cost calculator for an instant estimate, or read on for detailed 2025 pricing.
Two-Storey Extension Cost Summary 2025
A typical two-storey extension in Hampshire costs between £70,000 and £150,000 depending on size and specification. Here's what affects the price:
Build Costs Per Square Metre
- Standard specification: £1,600 - £2,200/m²
- Mid-range specification: £2,000 - £2,400/m²
- High specification: £2,400 - £2,800/m²
Important: Two-storey extensions are calculated on total floor area (both floors combined), making them more cost-effective than two separate single-storey builds.
Typical Two-Storey Extension Costs by Size
- 30m² total (15m² per floor): £54,000 - £75,000
- 50m² total (25m² per floor): £90,000 - £125,000
- 70m² total (35m² per floor): £126,000 - £175,000
Why Two-Storey Extensions Cost Less Per m²
Two-storey extensions are more cost-effective because:
- Shared foundations: One set of foundations supports both floors
- Shared roof: Single roof structure covers double the space
- Efficiency: Less groundwork relative to floor area gained
- Better ratio: More living space from same footprint
Two-Storey Extension Requirements
Planning Permission
Two-storey extensions almost always require planning permission in Hampshire (unlike many single-storey extensions which may be permitted development). Our Pre-Build package includes full planning application support.
Structural Calculations
Essential for two-storey builds due to:
- Increased foundation loading
- First floor structural requirements
- Connection to existing building
- Roof structure design
Building Regulations
More stringent requirements including:
- Staircase design and fire escape routes
- Sound insulation between floors
- Enhanced structural stability
- Window escape requirements for bedrooms
Two-Storey Extension Cost Breakdown
Example: 50m² two-storey rear extension in Basingstoke (25m² per floor)
| Item | Cost |
| Design Package (Pre-Build) | £1,950 + VAT |
| Build (50m² @ £2,000/m²) | £100,000 |
| Staircase | £3,000 |
| Bathroom (first floor) | £6,000 |
| Electrics and heating | £8,000 |
| Planning and building control fees | £1,200 |
| Total | £120,000 |
Two-Storey vs Single-Storey: Cost Comparison
For the same total floor area:
- 50m² two-storey (25m² per floor): £90,000 - £110,000
- 50m² single-storey: £110,000 - £140,000
- Saving: £20,000 - £30,000 with two-storey design
What You Can Achieve
A typical 50m² two-storey extension provides:
Ground Floor (25m²)
- Large kitchen-diner with island
- Bi-fold doors to garden
- Utility/boot room
First Floor (25m²)
- Master bedroom with en-suite
- Or two additional bedrooms
- Or bedroom plus home office
Get Your Two-Storey Extension Estimate
Our free extension cost calculator provides instant, personalised estimates for two-storey extensions in Hampshire.
Enter your project details to receive:
- Accurate build cost range
- Design package recommendations
- Planning permission guidance
- Detailed proposal by email
