London regional pricing
How Much Does a Builder Cost in Harrow?
Updated prices for . Harrow prices are typically 20% above the national average.
Price summary
Harrow Price Summary
| Service | Low | Average | High |
|---|---|---|---|
| Single Storey Extension | £35,850 | £59,750 | £95,600 |
| Double Storey Extension | £59,750 | £101,575 | £167,300 |
| Loft Conversion | £29,875 | £53,775 | £89,625 |
Prices include labour and materials. VAT may apply. Based on London regional pricing.
Full pricing
All Builder Prices in Harrow
Every price adjusted for Harrow using a 1.195x cost multiplier, rounded to the nearest £5.
| Job | Low | Average | High | Duration |
|---|---|---|---|---|
| Single Storey Extension | £35,850 | £59,750 | £95,600 | 8-12 weeks |
| Double Storey Extension | £59,750 | £101,575 | £167,300 | 12-20 weeks |
| Loft Conversion | £29,875 | £53,775 | £89,625 | 6-10 weeks |
| Garage Conversion | £9,560 | £17,925 | £29,875 | 2-4 weeks |
| Porch Build | £2,990 | £5,380 | £9,560 | 1-2 weeks |
| Garden Wall | £955 | £1,795 | £3,585 | 2-4 days |
| Knock Through Internal Wall | £1,195 | £2,150 | £4,185 | 2-4 days |
| Chimney Breast Removal | £1,435 | £2,390 | £4,185 | 2-4 days |
| Underpinning | £5,975 | £14,340 | £29,875 | 2-4 weeks |
| Damp Proof Course | £600 | £1,435 | £2,990 | 1-3 days |
| New Build Garage | £11,950 | £21,510 | £35,850 | 3-5 weeks |
| Outbuilding or Garden Room | £14,340 | £29,875 | £59,750 | 3-6 weeks |
| Structural Steelwork (RSJ Installation) | £1,195 | £2,150 | £3,585 | 1-2 days |
| Patio or Decking Build | £1,795 | £4,185 | £8,365 | 3-5 days |
Single Storey Extension
Low
£35,850
Average
£59,750
High
£95,600
8-12 weeks
Double Storey Extension
Low
£59,750
Average
£101,575
High
£167,300
12-20 weeks
Loft Conversion
Low
£29,875
Average
£53,775
High
£89,625
6-10 weeks
Garage Conversion
Low
£9,560
Average
£17,925
High
£29,875
2-4 weeks
Porch Build
Low
£2,990
Average
£5,380
High
£9,560
1-2 weeks
Garden Wall
Low
£955
Average
£1,795
High
£3,585
2-4 days
Knock Through Internal Wall
Low
£1,195
Average
£2,150
High
£4,185
2-4 days
Chimney Breast Removal
Low
£1,435
Average
£2,390
High
£4,185
2-4 days
Underpinning
Low
£5,975
Average
£14,340
High
£29,875
2-4 weeks
Damp Proof Course
Low
£600
Average
£1,435
High
£2,990
1-3 days
New Build Garage
Low
£11,950
Average
£21,510
High
£35,850
3-5 weeks
Outbuilding or Garden Room
Low
£14,340
Average
£29,875
High
£59,750
3-6 weeks
Structural Steelwork (RSJ Installation)
Low
£1,195
Average
£2,150
High
£3,585
1-2 days
Patio or Decking Build
Low
£1,795
Average
£4,185
High
£8,365
3-5 days
Regional comparison
How Harrow Compares
Average cost of single storey extension across regions.
Local insights
What Affects Builder Costs in Harrow?
Harrow'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 Harrow. 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 Harrow might quote £59,750 to £167,300 for double storey extension.
When getting quotes in Harrow, 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 Harrow
Explore costs for other services in the Harrow 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 Harrow.