Planning a house extension but unsure about the budget? We break down typical costs for single-storey, double-storey, and wrap-around extensions across Leicestershire.
A house extension is one of the most effective ways to add space and value to your home. But costs can vary enormously depending on the type of extension, the size, the specification, and your location. This guide gives you a realistic picture of what to budget for an extension in Leicestershire in 2025.
For a standard single-storey rear extension in Leicestershire, expect to budget between £1,500 and £2,200 per square metre for a good-quality build. This means a typical 20m² kitchen-diner extension might cost £30,000 to £44,000 — though specification choices, ground conditions, and the complexity of the design all affect the final figure significantly.
Double-storey extensions, which add rooms on both the ground and first floor, cost between £1,800 and £2,500 per m² because the additional structural work, scaffold, and roofing work adds to the cost. However, the cost per square metre is often more efficient than a single-storey build because you're sharing certain fixed costs — foundations, scaffold, and roof — across twice the floor area.
Wrap-around extensions, which extend across the rear and side of a property simultaneously, are the most complex and typically the most expensive, but they can transform a property's layout dramatically. Budget from £2,200 per m² upwards for this type of project.
On top of the core build cost, you need to account for architectural fees (typically 5–10% of the build cost), planning application fees (currently £258 for householder applications in England), building regulation fees, and structural engineer reports. Interior fitting-out costs — kitchen units, flooring, decoration — are also separate from the build cost and can add £10,000–£30,000 or more depending on your choices.
Always include a contingency of at least 10–15% in your total budget. Every construction project carries an element of the unknown — from ground conditions that require additional foundation work, to hidden services that need diverting. A well-run project absorbs these surprises without stress because the budget has provision for them.
VAT at 20% is payable on most residential extension work. However, if you are extending a listed building or carrying out certain types of conversion, you may be eligible for reduced or zero VAT — speak to your accountant or builder for clarification on your specific project.
The best way to establish a realistic budget for your extension is to get detailed, itemised quotes from established local builders. At Spectrum Construction, we provide free, no-obligation quotes for all extension projects across Leicester and Leicestershire.
Key Takeaways
- Single-storey rear extension: £1,500–£2,200 per m²
- Double-storey extension: £1,800–£2,500 per m²
- Always budget a 10–15% contingency
- Planning fees and architect costs are additional
- VAT is charged at 20% on most extension work
