How much does a house extension cost in Manchester?

The most common question we get — and the one most builders answer least honestly. Here are the real numbers for Greater Manchester in 2026, based on projects we’ve actually priced and built.

The headline figures

*Totals assume a typical 18–30m² footprint, exclude the kitchen itself and VAT. Every site is different — treat these as planning figures, not quotes.

What moves the price

• Glazing. The single biggest swing. Standard French doors might cost £2,500; a structural glazed corner or oversized sliders can add £15,000–£25,000 alone.
• Ground conditions. Clay, drains, tree roots and sloping gardens all affect foundation costs. This is why a serious builder visits before quoting.
• Steelwork. Opening up the existing rear wall means steels, padstones and structural design. Bigger openings, bigger steels, bigger money.
• Specification. Underfloor heating, flush thresholds, feature rooflights and premium flooring each add real cost — and real value.
• The kitchen. Usually excluded from build quotes. Budget £12,000–£40,000+ depending on where you shop.

The costs cheap quotes leave out

When one quote is 25% below the others, it’s rarely because that builder found magic bricks. It’s usually one or more of these missing: building control fees, structural engineer’s design, skips and waste removal, scaffolding, making good the existing house where old meets new, decoration, and VAT. Ask for an itemised quotation and these gaps become obvious in about thirty seconds.

Design and professional fees

Budget £3,000–£6,000 for architectural drawings, structural calculations, planning or lawful development applications and building regulations submission. On a design-and-build contract with us, this is coordinated inside one programme rather than left for you to project-manage.

Is it worth it?

In the neighbourhoods we work — Didsbury, Chorlton, Prestwich, Worsley, Bramhall, Wilmslow — a well-built kitchen extension typically adds more value than it costs, and transforms how the house lives day to day. A badly built one does neither. The builder is the difference.