Extension cost per m² in Brighton
Extension cost by size in Brighton
Each row multiplies the current £1,800–£3,000 per m² national benchmark by floor area and then applies the same regional factor.
What can change a real Brighton quote?
- Floor area and number of storeys
- London and regional labour rates
- Steelwork and structural changes
- Kitchen or bathroom installation
- Glazing and door specification
- Finish level, access and contingency
Local planning considerations
Coastal exposure, conservation areas, parking and restricted access can affect individual quotations beyond the broad South East planning model.
- Exterior specifications may need more attention where a property is exposed to coastal weather and salt-laden air.
- Tight street access or controlled parking can change waste, scaffold and delivery logistics even when the underlying project is unchanged.
- Check listed-building or conservation constraints before assuming a standard window, roof, rendering or extension specification.
How the regional model works
The 1.15× factor places this planning estimate 15% above the national planning baseline. We keep that modelling assumption separate from the dated national benchmark so users can see which part comes from an external source and which part is UK Home Costs modelling.
Sources
House Extension: Cost Breakdown 2026
Published / checked: June 2026
Used for: Extension cost-per-m² benchmarks and common add-on costs
Construction output price indices
Published / checked: 13 August 2026
Used for: Construction price trend and update checks
Frequently asked questions
How much does a house extension cost in Brighton in 2026?
Our modelled Brighton planning rate is about £2,050–£3,450 / m², based on the current national £1,800–£3,000 per m² benchmark and the South East regional factor. This is not an observed city-wide quote average.
How much is a 20m² extension in Brighton?
Applying the same regional model gives about £41,400–£69,000 before VAT for a straight-line 20m² example. Structural work, glazing, kitchens, bathrooms and access can move a real quote outside that range.
Why is the Brighton estimate different from the UK benchmark?
UK Home Costs applies a 1.15× South East planning factor, placing the model 15% above the national planning baseline. It is our modelling assumption rather than an external city price index.
Does the extension figure include VAT and professional fees?
The national benchmark is stated before VAT. Do not assume architect, structural engineer, planning, building-control, party-wall or specialist survey fees are included unless a contractor quote says so.