Extension cost per m² in Birmingham
Extension cost by size in Birmingham
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 Birmingham 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
Actual contractor pricing can vary by access, project scale and specification, so compare itemised quotes against the planning range.
- City-centre, inner-urban and suburban projects can have very different access, parking and delivery conditions.
- Separate structural repairs or remedial work from the headline renovation budget when the existing condition is uncertain.
- Ask contractors to identify waste, scaffold, professional fees and approvals so quotes can be compared against the same scope.
How the regional model works
The 0.98× factor places this planning estimate 2% below 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 Birmingham in 2026?
Our modelled Birmingham planning rate is about £1,750–£2,950 / m², based on the current national £1,800–£3,000 per m² benchmark and the West Midlands regional factor. This is not an observed city-wide quote average.
How much is a 20m² extension in Birmingham?
Applying the same regional model gives about £35,300–£58,800 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 Birmingham estimate different from the UK benchmark?
UK Home Costs applies a 0.98× West Midlands planning factor, placing the model 2% below 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.