Getting a straight answer on extension prices is hard, partly because every Brighton home is different. This guide gives you realistic ranges for a single storey rear or side extension locally, explains what actually moves the number, and flags the costs people forget to budget for.
As a rough working figure, most single storey extensions in Brighton and Hove land between £2,500 and £3,400 per square metre for the build itself, before fittings. A modest 15 sqm rear extension therefore tends to sit around £40,000 to £55,000, while a larger 30 sqm open plan kitchen extension often runs £75,000 to £100,000 once you include decent glazing and a proper kitchen.
Brighton sits at the higher end of regional pricing. Tight terraced access, parking restrictions, and the cost of skilled trades in the city all push figures above what you might see in rural Sussex.
The biggest variable is usually access. Many Brighton terraces have no side return and no rear vehicle access, so materials and spoil are carried through the house by hand. That adds labour and time compared with a property where a skip and digger can reach the garden directly.
Ground conditions matter too. Sloping plots in areas like Hanover, Hollingdean and Roundhill often need stepped or deeper foundations, and the chalk and clay around the city can mean more groundwork than expected. Removing a structural wall to open up a kitchen also brings in a steel beam and a structural engineer's calculations.
The headline build figure rarely includes everything. Planning or a lawful development certificate, structural engineering, and Building Control fees all sit on top, and party wall agreements are common in the city's terraces where you share walls with neighbours.
Finishes are where budgets quietly blow out. Kitchens, flooring, underfloor heating, glazing upgrades and landscaping the disturbed garden can easily add £15,000 to £30,000 on a kitchen extension, so it is worth pricing these early rather than treating them as an afterthought.
Be wary of any quote given before a builder has seen the site, especially in Brighton where access varies so much street to street. A reliable price comes from a measured survey, drawings, and an itemised quotation rather than a rate per square metre alone.
Where possible, get the build broken down into stages with a clear specification for fittings, so you are comparing like with like across builders. A slightly higher quote with everything written down often works out cheaper than a low headline figure full of provisional sums.
Many rear extensions fall under permitted development, but conservation areas and listed buildings, which are common in central Brighton and Hove, usually remove those rights. It is always worth checking with the council or applying for a lawful development certificate before starting.
A typical single storey extension takes around 10 to 16 weeks on site once work begins, depending on size, glazing lead times and groundwork. Restricted access on terraced streets can add a few weeks to that.
A well built kitchen or living extension usually adds value in a strong market like Brighton, though the uplift varies by area and street. Spending sensibly relative to local ceiling prices matters more than spending the most.
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