London regional pricing
How Much Does a Builder Cost in Westminster?
Updated prices for . Westminster prices are typically 40% above the national average.
Price summary
Westminster Price Summary
| Service | Low | Average | High |
|---|---|---|---|
| Single Storey Extension | £42,090 | £70,150 | £112,240 |
| Double Storey Extension | £70,150 | £119,255 | £196,420 |
| Loft Conversion | £35,075 | £63,135 | £105,225 |
Prices include labour and materials. VAT may apply. Based on London regional pricing.
Full pricing
All Builder Prices in Westminster
Every price adjusted for Westminster using a 1.403x cost multiplier, rounded to the nearest £5.
| Job | Low | Average | High | Duration |
|---|---|---|---|---|
| Single Storey Extension | £42,090 | £70,150 | £112,240 | 8-12 weeks |
| Double Storey Extension | £70,150 | £119,255 | £196,420 | 12-20 weeks |
| Loft Conversion | £35,075 | £63,135 | £105,225 | 6-10 weeks |
| Garage Conversion | £11,225 | £21,045 | £35,075 | 2-4 weeks |
| Porch Build | £3,510 | £6,315 | £11,225 | 1-2 weeks |
| Garden Wall | £1,120 | £2,105 | £4,210 | 2-4 days |
| Knock Through Internal Wall | £1,405 | £2,525 | £4,910 | 2-4 days |
| Chimney Breast Removal | £1,685 | £2,805 | £4,910 | 2-4 days |
| Underpinning | £7,015 | £16,835 | £35,075 | 2-4 weeks |
| Damp Proof Course | £700 | £1,685 | £3,510 | 1-3 days |
| New Build Garage | £14,030 | £25,255 | £42,090 | 3-5 weeks |
| Outbuilding or Garden Room | £16,835 | £35,075 | £70,150 | 3-6 weeks |
| Structural Steelwork (RSJ Installation) | £1,405 | £2,525 | £4,210 | 1-2 days |
| Patio or Decking Build | £2,105 | £4,910 | £9,820 | 3-5 days |
Single Storey Extension
Low
£42,090
Average
£70,150
High
£112,240
8-12 weeks
Double Storey Extension
Low
£70,150
Average
£119,255
High
£196,420
12-20 weeks
Loft Conversion
Low
£35,075
Average
£63,135
High
£105,225
6-10 weeks
Garage Conversion
Low
£11,225
Average
£21,045
High
£35,075
2-4 weeks
Porch Build
Low
£3,510
Average
£6,315
High
£11,225
1-2 weeks
Garden Wall
Low
£1,120
Average
£2,105
High
£4,210
2-4 days
Knock Through Internal Wall
Low
£1,405
Average
£2,525
High
£4,910
2-4 days
Chimney Breast Removal
Low
£1,685
Average
£2,805
High
£4,910
2-4 days
Underpinning
Low
£7,015
Average
£16,835
High
£35,075
2-4 weeks
Damp Proof Course
Low
£700
Average
£1,685
High
£3,510
1-3 days
New Build Garage
Low
£14,030
Average
£25,255
High
£42,090
3-5 weeks
Outbuilding or Garden Room
Low
£16,835
Average
£35,075
High
£70,150
3-6 weeks
Structural Steelwork (RSJ Installation)
Low
£1,405
Average
£2,525
High
£4,210
1-2 days
Patio or Decking Build
Low
£2,105
Average
£4,910
High
£9,820
3-5 days
Regional comparison
How Westminster Compares
Average cost of single storey extension across regions.
Local insights
What Affects Builder Costs in Westminster?
Westminster's housing stock ranges from Georgian and Victorian terraces to post-war estates and modern new-builds. Properties across areas like Islington, Hackney and Brixton vary enormously in age, layout and condition, all of which directly affect builder costs. Older properties tend to need more preparation work and present access challenges that push prices toward the higher end of the ranges shown above.
London is the most expensive part of the UK for trade work, with labour rates running around 24% above the national average. This reflects the high cost of living, congestion charges, and expensive parking that tradespeople factor into their quotes. Despite the higher prices, there is no shortage of qualified builder professionals across the capital. Prices still vary by 30-50% between tradespeople for the same job, making multiple quotes essential.
Several factors affect what you will pay for builder work in Westminster. The scope and complexity of the job is the biggest driver — straightforward work in accessible locations will be at the lower end, while anything involving older properties, difficult access, or structural complications will cost more. Material choices also make a significant difference; opting for premium brands or higher-spec products can add 20-40% to the total. For larger jobs, a builder in Westminster might quote £70,150 to £196,420 for double storey extension.
When getting quotes in Westminster, aim for at least three from different qualified professionals. Ask each one to visit and assess the work in person rather than quoting over the phone. A good builder will check the existing setup, identify any potential complications, and give you a detailed breakdown of costs. Be wary of quotes that seem significantly cheaper than others — they may be cutting corners on materials or not including everything in the price. Always check qualifications, insurance and recent reviews before hiring.
More services
Other Services in Westminster
Explore costs for other services in the Westminster area.
40 services — scroll to explore
UK-wide pricing
Builder Costs in Other Cities
Compare builder prices across the UK.
Common questions
Frequently Asked Questions
Common questions about builder costs in Westminster.