What it costs, before you ask
Most builders make you book a visit to find out. These are our real 2026 bands, what sits inside them, and the choices that move the number. Build yours online for a figure specific to you.
Get an instant priceGarden rooms
Insulated shell, glazing, certified electrics, heating, finished interior, ground screws, waste removal, VAT.
Extensions
Architectural drawings, structural calcs, groundwork, shell, roof, glazing, electrics, plastered finish, building control.
Loft conversions
Structural design, scaffold, roof works, dormer or rooflights, staircase, insulation, electrics, fire compliance, completion certificate.
Golf simulator rooms
Raised-height insulated shell, groundwork, blackout glazing, hitting turf, impact screen, projector, launch monitor, calibration.
Saunas
Insulated cedar cabin, base, vapour barrier, certified electrics, heater and stones, benching, glass door, commissioning.
Four things decide where you land in the band
Everything else is rounding. If you understand these four, you can predict your own quote to within a few thousand pounds.
Size, but not linearly
Foundations, delivery and mobilisation are largely fixed, so cost per square metre falls as the build grows. If you’re hesitating between two sizes, the bigger one is usually better value per metre.
Glazing and openings
Glass is the single biggest swing in most quotes. A 4m aluminium slider or a four-panel bifold can be several times the cost of French doors in the same wall.
Access and ground
A wide side gate means a machine and two days of groundwork. A metre-wide gate means barrows and hand-carrying, and that shows up as labour days.
Water and drainage
The moment a project includes a WC, shower or kitchen, you’re into drainage connections, possibly a build-over agreement, and more groundwork.
Spread it over months instead
Around a third of our customers use finance. Terms from 24 to 120 months, soft-search decision, no early settlement fees.