Extension cost per m² in Bristol
Extension cost by size in Bristol
Each row multiplies the current £1,800–£3,000 per m² national benchmark by floor area and then applies the same South West factor.
What can change a real Bristol 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
Regional adjustment is only one part of the estimate; access, structural work and specification can have a larger effect on individual projects.
- Sloping plots, steps and restricted rear access can materially affect excavation, landscaping and waste-handling allowances on some homes.
- Older or altered properties should be budgeted with a separate contingency for hidden fabric and structural conditions.
- For constrained streets, compare quotes on a like-for-like basis for parking, scaffold, skips and delivery assumptions.
How the regional model works
The 1.07× factor places this planning estimate 7% above the national planning baseline. We keep that modelling assumption separate from the dated national benchmark so users can see exactly 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 Bristol in 2026?
Our modelled Bristol planning rate is about £1,950–£3,200 / m², based on the current national £1,800–£3,000 per m² benchmark and the South West regional factor. This is not an observed city-wide quote average.
How much is a 20m² extension in Bristol?
Applying the same regional model to the current national benchmark gives about £38,500–£64,200 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 Bristol estimate different from the UK benchmark?
UK Home Costs applies a 1.07× South West planning factor, which places the model 7% above the national planning baseline. The factor is our modelling assumption rather than an external city price index.
Does the extension figure include VAT and professional fees?
The national benchmark used here 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 explicitly.