Planning a house extension is an exciting step — whether you need more space, want to increase property value, or improve your home’s layout. However, one of the biggest questions homeowners ask is:
👉 “How much will it cost?”
In this guide, we break down extension costs in the UK, what affects pricing, and how to budget effectively.
Average Cost of a House Extension
In the UK, typical extension costs are:
- £1,500 – £2,500 per m² (basic build)
- £2,500 – £3,500+ per m² (high-end finish)
Example:
- Small extension (20m²): £30,000 – £70,000
- Medium extension (40m²): £60,000 – £140,000
- Large extension: £100,000+
What Affects the Cost?
1. Size of the Extension
Larger extensions cost more overall, but cost per m² may decrease slightly.
2. Type of Extension
- Single-storey: cheaper
- Double-storey: more cost-effective per m²
- Wrap-around: more complex
- Loft conversion: different pricing structure
3. Location
Costs vary depending on location:
- London & South East: higher
- Midlands & North: lower
- Coastal/rural areas: moderate
4. Materials and Finish
Your choices massively impact cost:
- Basic materials = lower cost
- High-end finishes = significantly higher
5. Labour Costs
Labour can account for 40–60% of total cost.
Hiring experienced, reputable builders ensures quality work — but may cost more upfront.
Hidden Costs to Consider
Many homeowners underestimate:
- Planning fees
- Structural engineer costs
- Building regulations
- VAT (20%)
- Landscaping after build
Planning Permission
Not all extensions require planning permission.
You may be covered under:
👉 Permitted Development Rights
But always check with your local authority.
How to Save Money
- Keep the design simple
- Use standard materials
- Get multiple quotes
- Plan thoroughly
Choosing the Right Builder
Your builder plays a huge role in:
- cost control
- project success
- quality of finish
Why FindaTradie helps
With FindaTradie:
- ✔ You can find verified builders
- ✔ Reviews are checked for authenticity
- ✔ You can compare professionals easily
We focus on trust and transparency, not just generating leads.
Is an Extension Worth It?
In most cases, yes.
Benefits include:
- Increased property value
- More living space
- Improved functionality
A well-built extension can add 10–20% to your home’s value.
Final Thoughts
A house extension is a significant investment, but with proper planning and the right builder, it can transform your home.
Take time to:
- understand costs
- plan your budget
- choose a trusted professional
👉 Ready to start your project? Find trusted builders on FindaTradie today.