A single-storey extension is one of the most common building projects we deliver across Redditch, Birmingham and the wider West Midlands. It’s also the project our clients ask us to price most often, so here is an honest, up-to-date guide to what a single-storey extension actually costs in 2026.
Rough cost ranges for 2026
As a rule of thumb, a single-storey rear extension in the West Midlands in 2026 will cost somewhere in these ranges:
- Basic finish, standard shell: £1,800 – £2,200 per m²
- Mid-range with good glazing and finish: £2,200 – £2,800 per m²
- High-spec with structural glazing, vaulted ceilings, premium kitchen: £2,800 – £3,800 per m²
That means a typical 25 m² single-storey rear extension in Redditch might land anywhere between £45,000 and £95,000 depending on specification. It is a wide range because the finish is the biggest variable.
What actually drives the cost?
Foundations and ground conditions
Clay ground, sloping sites or nearby trees can push foundation depth from 1m to 2.5m or deeper. Every extra metre of foundation depth adds cost.
Structural openings
Removing an existing rear wall to open up into the extension requires steel beams and structural calculations. A single opening is straightforward. A completely open rear elevation with three or four steels adds several thousand pounds.
Glazing
Standard uPVC bi-folds run around £500–£700 per linear metre. Aluminium bi-folds are £1,000–£1,600. Structural glazing and slim-frame sliding doors can hit £2,500 per linear metre. This choice alone can move a project by £10,000.
Kitchen and finish
If the extension will house a new kitchen, the kitchen itself is often the biggest single line item. Budget kitchens start around £5,000. Mid-range kitchens land at £15,000–£25,000. Bespoke units and premium worktops can easily exceed £40,000.
Common cost extras clients underestimate
- Planning application fees and drawings if planning permission is required
- Building Control application and inspection fees
- Structural engineer calculations
- Party wall surveyor fees where you share a boundary with neighbours
- Waste removal and skip hire
- Making good the existing house where it meets the new extension
- Redecoration of existing rooms that connect to the new space
How long will it take?
A typical single-storey rear extension in Redditch runs 10–14 weeks on site once we break ground. Add 8–12 weeks before that for planning approval if required. Some projects that fall under Permitted Development can start much sooner.
How to get a genuinely useful quote
The cheapest quote is rarely the cheapest job. What you want is a fixed-price quote that spells out exactly what is included and what is not. At CK Construction our quotes include a full breakdown of every trade and every material choice, with no “PC sums” that can inflate later. If you are considering an extension in Redditch, Birmingham, Solihull or Warwickshire, we would be pleased to visit the property and give you a genuine fixed price.
Serving homeowners across Worcester, Malvern, Birmingham, Solihull, Gloucester and the wider region.