If you're thinking about extending your home in Essex, the first question is always: "How much will it cost?" The honest answer is — it depends. But we can give you realistic ranges based on hundreds of projects we've completed across Basildon, Billericay, Brentwood, and the wider Essex area.
Average Extension Costs in Essex (2025)
Prices include VAT and are based on a standard specification. Actual costs depend on site conditions, specification, and finishes.
What Affects the Cost?
No two extensions are the same. Here are the main factors that move the price up or down:
Size and complexity
A simple rectangular rear extension costs less per m² than an L-shaped wrap-around with structural steelwork.
Foundations
If your ground conditions require deeper or piled foundations (common in parts of Basildon and South Essex), this adds cost.
Specification and finishes
A basic extension with standard fittings costs significantly less than one with underfloor heating, bifold doors, quartz worktops, and high-end bathrooms.
Structural work
Removing load-bearing walls, installing steel beams, or underpinning existing foundations all add to the budget.
Access
Tight access to the rear of the property can increase labour and plant costs.
Planning and design fees
Architectural drawings, structural engineer calculations, and planning application fees typically add £3,000–£6,000.
How to Get an Accurate Quote
Online calculators give rough estimates, but the only way to get an accurate price is to have a builder visit your property. We offer free, no-obligation site visits where we'll discuss your plans, measure up, and provide a detailed written quotation.
If you're at the early stages and don't have drawings yet, we can still give you a ballpark figure to help you decide whether to proceed with the design. Many of our clients come to us before they've committed to architectural plans.
Is a House Extension Worth It?
In most cases, yes. A well-designed extension can add 10–20% to your property value — and in Essex, where the average house price is over £350,000, that's a significant return. More importantly, you get the space you need without the cost and stress of moving.
We've been building extensions across Essex for over 45 years. If you'd like to discuss your project, get in touch — we're always happy to talk.
Get a Free Extension Quote
Tell us about your project and we'll provide a detailed, no-obligation quotation.