How Much Does a Home Extension Cost in Sussex?
One of the first questions homeowners understandably ask when considering an extension is how much the project is likely to cost.
The honest answer is that construction costs can vary significantly depending on the size, specification and complexity of the proposal. However, understanding some realistic budget ranges early on can help homeowners approach projects with much more confidence and clarity.
Across Sussex and the South Coast, many residential extensions currently fall somewhere between £2,000–£3,000+ per m² for construction costs alone, although this can vary considerably depending on the project.
What Affects the Cost of an Extension?
No two projects are exactly the same, and several factors can influence the overall construction cost of a home extension.
Some of the biggest factors include:
The size of the extension
Ground conditions and foundations
Structural complexity
Roof design
Glazing and doors
Internal specification and finishes
Kitchen and bathroom costs
Access to the site
Drainage works
Structural steel requirements
Even two extensions of a similar size can vary significantly in overall cost depending on the specification and complexity involved.
Typical Extension Costs in Sussex
As a very broad guide:
Single-Storey Rear Extensions
Many single-storey rear extensions across Sussex currently range from around £40,000–£90,000+ depending on size and specification.
Double-Storey Extensions
Double-storey extensions can often provide better value per square metre overall, although total project costs are naturally higher due to the additional floor area involved.
Loft Conversions
Many loft conversions across Sussex currently start from around £40,000 upwards, although dormers, complex roof structures and high-end specifications can increase this significantly.
What Other Costs Should Be Considered?
Alongside construction costs, homeowners should also allow for professional and statutory costs associated with the project.
These may include:
Measured surveys
Planning drawings
Building Regulations drawings
Structural engineer fees
Planning application fees
Building Control fees
Party wall matters
Thames Water or sewer build-over agreements (where applicable)
Understanding these additional stages early on often helps projects run much more smoothly overall.
Is It Worth Extending?
For many homeowners, extending can often provide a far more practical and cost-effective solution than moving house entirely.
Well-considered residential design can dramatically improve:
Natural light
Layout flow
Connection to the garden
Family living space
Kitchen and dining arrangements
Storage and utility areas
In many cases, relatively modest layout changes can also have a surprisingly significant impact on how a home feels and functions day-to-day.
The Importance of Early Design
One of the most valuable stages of any residential project is often the early design process itself.
Good design is not simply about increasing floor area — it is about understanding how people actually live and shaping spaces around that.
Carefully considered layouts, circulation and natural light can often make a far greater difference than simply building bigger.
Starting the Process
The early stages of a residential project can often feel overwhelming when trying to balance ideas, budgets, planning considerations and construction costs all at once.
At Downland Studio, projects are approached collaboratively and practically, helping homeowners across Worthing, West Sussex and the South Coast navigate the process clearly from initial ideas through to planning and technical design.
If you’re considering extending your home and would like some honest advice before getting started, feel free to get in touch for an informal conversation.