London regional pricing

How Much Does a Builder Cost in Merton?

Updated prices for . Merton prices are typically 35% above the national average.

14 services priced
London region
Updated

Price summary

Merton Price Summary

Service Low Average High
Single Storey Extension £40,470 £67,450 £107,920
Double Storey Extension £67,450 £114,665 £188,860
Loft Conversion £33,725 £60,705 £101,175

Prices include labour and materials. VAT may apply. Based on London regional pricing.

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Full pricing

All Builder Prices in Merton

Every price adjusted for Merton using a 1.349x cost multiplier, rounded to the nearest £5.

Single Storey Extension

Low

£40,470

Average

£67,450

High

£107,920

8-12 weeks

Double Storey Extension

Low

£67,450

Average

£114,665

High

£188,860

12-20 weeks

Loft Conversion

Low

£33,725

Average

£60,705

High

£101,175

6-10 weeks

Garage Conversion

Low

£10,790

Average

£20,235

High

£33,725

2-4 weeks

Porch Build

Low

£3,375

Average

£6,070

High

£10,790

1-2 weeks

Garden Wall

Low

£1,080

Average

£2,025

High

£4,045

2-4 days

Knock Through Internal Wall

Low

£1,350

Average

£2,430

High

£4,720

2-4 days

Chimney Breast Removal

Low

£1,620

Average

£2,700

High

£4,720

2-4 days

Underpinning

Low

£6,745

Average

£16,190

High

£33,725

2-4 weeks

Damp Proof Course

Low

£675

Average

£1,620

High

£3,375

1-3 days

New Build Garage

Low

£13,490

Average

£24,280

High

£40,470

3-5 weeks

Outbuilding or Garden Room

Low

£16,190

Average

£33,725

High

£67,450

3-6 weeks

Structural Steelwork (RSJ Installation)

Low

£1,350

Average

£2,430

High

£4,045

1-2 days

Patio or Decking Build

Low

£2,025

Average

£4,720

High

£9,445

3-5 days

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Regional comparison

How Merton Compares

Average cost of single storey extension across regions.

Merton
+35% £67,450
National Average
baseline £50,000
London
+24% £62,150

Local insights

What Affects Builder Costs in Merton?

Merton'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 Merton. 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 Merton might quote £67,450 to £188,860 for double storey extension.

When getting quotes in Merton, 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.

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More services

Other Services in Merton

Explore costs for other services in the Merton area.

40 services — scroll to explore

Common questions

Frequently Asked Questions

Common questions about builder costs in Merton.

How much does a builder cost in Merton in 2026?
Single Storey Extension in Merton typically costs between £40,470 and £107,920, with the average being around £67,450. Prices vary depending on the scope of work, materials used, and the specific requirements of your property.
Are builder prices cheaper in Merton than London?
Merton prices are 35% above the national average, though still comparable to London for single storey extension.
How do I find a good builder in Merton?
Get at least three quotes from different tradespeople, check recent reviews, and ask whether the quote includes VAT and everything you need. A detailed written quote that breaks down all costs is a good sign. Always check qualifications, insurance and recent reviews before hiring.
What affects builder prices in Merton?
The main factors are the scope and complexity of what you need, the options and products chosen, and local market rates. Merton rates are 35% above the national average. Getting multiple quotes is the best way to ensure a fair price.
Do builder prices include materials in Merton?
The prices shown on this page include all typical costs. However, when getting real quotes, always confirm what is and isn't included. Some tradespeople break out costs separately, while others give an all-in price. Ask for a detailed breakdown before agreeing to any work.