If you're considering adding an extension to your Kent home, one of the first questions you'll have is "how much will it cost?" It's a fair question, and while every project is different, we can give you realistic ballpark figures based on our experience building extensions across Tonbridge, Tunbridge Wells, Sevenoaks, Maidstone and the wider Kent area.
Average Extension Costs in Kent (2025)
Here's what you can expect to pay for different types of extensions in Kent this year:
Single storey rear extension (3m x 5m): £35,000 - £55,000
This is the most popular type of extension we build. It typically adds a new kitchen-diner or enlarged living space. The price includes groundworks, building work, electrics, plumbing, plastering and decoration.
Single storey side return extension: £25,000 - £40,000
Common on Victorian and Edwardian terraces, side returns make use of that narrow alley space to create a more open-plan kitchen or dining area.
Double storey extension: £60,000 - £100,000
Going up as well as out gives you significantly more space. You might add a larger kitchen-diner downstairs with a bedroom and en-suite above.
Wrap-around extension: £70,000 - £120,000
Combining rear and side extensions creates the maximum additional space and often transforms a home completely.
What Affects the Cost?
Several factors influence what you'll pay for an extension in Kent:
Location within Kent: Labour and material costs can vary. Projects in affluent areas like Sevenoaks or Tunbridge Wells sometimes cost more due to higher specifications and access challenges with larger properties.
Specification and finishes: A basic extension with standard finishes costs less than one with bi-fold doors, underfloor heating, and a high-end kitchen. The difference can be tens of thousands of pounds.
Ground conditions: Kent has varied geology. Clay soil, high water tables, or proximity to trees can mean more expensive foundations.
Access: If materials need to be carried through the house rather than delivered directly to site, labour costs increase.
Getting Value for Money
The cheapest quote isn't always the best value. We've seen homeowners in Tonbridge and Maidstone spend more fixing problems caused by cutting corners than they saved on the original build. Look for a builder who:
- Provides a detailed, itemised quote
- Has verifiable local references
- Offers a clear payment schedule
- Is happy to answer all your questions
Get a Quote for Your Kent Extension
Ready to find out what your extension will cost? We offer free, no-obligation quotes for homeowners across Kent. Call us on 01732 905968 or get in touch online to arrange a site visit.