Extension Cost Calculator

Know your
budget before
you build

Planning a house extension but unsure what to budget? Get an instant estimate based on your build type, specification and floor area — then request an accurate quote from our team.

Years Experience

Projects Completed

Star Rated

Build type

Specification

Approx. floor area

10m²

10 m²150 m²

Estimated cost (ex. VAT)Standard · 10m² · Single storey

£23,000 – £27,600

£27,600 – £33,120 inc. VAT

Estimates are indicative only. Contact Acura for an accurate, no-obligation quote.

Pricing breakdown

How much does a
house extension cost?

The cost of a house extension in the UK typically ranges from £2,300 to £3,300 per m² depending on the specification chosen. Below is a guide to what each tier includes.

Standard spec

Quality materials and finishes, functional layouts, standard glazing and joinery. Ideal for adding practical space without a premium price tag.

Standard spec

Quality materials and finishes, functional layouts, standard glazing and joinery. Ideal for adding practical space without a premium price tag.

Mid-range spec

Enhanced finishes, better quality windows and doors, upgraded kitchen or bathroom fittings. The most popular choice for growing families.

Mid-range spec

Enhanced finishes, better quality windows and doors, upgraded kitchen or bathroom fittings. The most popular choice for growing families.

High-end spec

Premium materials throughout, bespoke joinery, large-format glazing and luxury fittings. For homeowners who want the best without compromise.

High-end spec

Premium materials throughout, bespoke joinery, large-format glazing and luxury fittings. For homeowners who want the best without compromise.

All prices are subject to VAT at 20%. Estimates are based on typical build conditions and do not include planning, structural engineering or party wall agreements where required.

Build types

Single vs double storey extensions

A single storey extension is the more straightforward option — it extends the ground floor footprint of your home and is often the quickest route to more living space. Costs are calculated directly on the floor area added.

A double storey extension adds space on both ground and first floors simultaneously. While the overall cost is higher, you gain significantly more space for the investment and the cost per m² of usable floor area is lower than building two separate extensions at different times.

Frequently Asked Questions

How accurate is this calculator?

Does the price include VAT?

Do I need planning permission for a house extension?

How long does a house extension take to build?

What's included in your quote?

How accurate is this calculator?

Does the price include VAT?

Do I need planning permission for a house extension?

How long does a house extension take to build?

What's included in your quote?

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Single vs double storey extensions

Build types

A single storey extension is the more straightforward option — it extends the ground floor footprint of your home and is often the quickest route to more living space. Costs are calculated directly on the floor area added.

A double storey extension adds space on both ground and first floors simultaneously. While the overall cost is higher, you gain significantly more space for the investment and the cost per m² of usable floor area is lower than building two separate extensions at different times.

Know yourbudget beforeyou build

Know yourbudget beforeyou build

How much does ahouse extension cost?

How much does ahouse extension cost?

Standard spec

Standard spec

Mid-range spec

Mid-range spec

High-end spec

High-end spec

Single vs double storey extensions

Single vs double storey extensions

A single storey extension is the more straightforward option — it extends the ground floor footprint of your home and is often the quickest route to more living space. Costs are calculated directly on the floor area added.

A double storey extension adds space on both ground and first floors simultaneously. While the overall cost is higher, you gain significantly more space for the investment and the cost per m² of usable floor area is lower than building two separate extensions at different times.

Frequently Asked Questions

Single vs double storey extensions

A single storey extension is the more straightforward option — it extends the ground floor footprint of your home and is often the quickest route to more living space. Costs are calculated directly on the floor area added.

A double storey extension adds space on both ground and first floors simultaneously. While the overall cost is higher, you gain significantly more space for the investment and the cost per m² of usable floor area is lower than building two separate extensions at different times.

Know your
budget before
you build

Know your
budget before
you build

How much does a
house extension cost?

How much does a
house extension cost?