Extension Cost Calculator | Guide-Price Tool

1. What type of extension?

Choose oneSingle-storeyRear or side, one floorTwo-storeyGround and first floorSide returnBeside a terraced outriggerWraparoundSide return plus rear, L-shapedOrangeryBrick piers, lantern roof

Kitchen, bedroom and utility extensions are usually one of these layouts. Porches, annexes and design-only services are priced on their own pages.

2. How big, and where?

Width4.0 m

Depth (how far it comes out)4.0 m

Your region

3. Finish and extras

SpecificationEssentialSimple shape, standard brick or render, flat roof with rooflights, standard doors and windows.Standard Middle optionMatched brickwork, roof lantern or several rooflights, wide sliding or bifold doors, quality finishes.PremiumComplex shape or structure, large-format glazing, cladding details, high-end finishes throughout.

Optional extras Wide sliding or bifold doors (3–4 m) (£4,500 – £9,500) Roof lantern or extra rooflights (£2,000 – £5,500) Mid-range kitchen, supplied and fitted (£9,000 – £20,000) Wet underfloor heating to the new floor (£1,800 – £4,000) Design pack: survey, planning and building regs drawings (£2,200 – £3,800)

4. Send it to us

Your guide range is shown alongside. Send it and we will call to arrange a free site visit (islands by arrangement); nothing is booked without your agreement.

Extension guide-price tool

1. What type of extension?

2. How big, and where?

3. Finish and extras

4. Send it to us