South West regional pricing

How Much Does a Builder Cost in Cornwall?

Updated prices for . Cornwall prices are typically 12% below the national average.

14 services priced
South West region
Updated

Price summary

Cornwall Price Summary

Service Low Average High
Single Storey Extension £26,310 £43,850 £70,160
Double Storey Extension £43,850 £74,545 £122,780
Loft Conversion £21,925 £39,465 £65,775

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

Ad Slot -- In-Content 1

Full pricing

All Builder Prices in Cornwall

Every price adjusted for Cornwall using a 0.877x cost multiplier, rounded to the nearest £5.

Single Storey Extension

Low

£26,310

Average

£43,850

High

£70,160

8-12 weeks

Double Storey Extension

Low

£43,850

Average

£74,545

High

£122,780

12-20 weeks

Loft Conversion

Low

£21,925

Average

£39,465

High

£65,775

6-10 weeks

Garage Conversion

Low

£7,015

Average

£13,155

High

£21,925

2-4 weeks

Porch Build

Low

£2,195

Average

£3,945

High

£7,015

1-2 weeks

Garden Wall

Low

£700

Average

£1,315

High

£2,630

2-4 days

Knock Through Internal Wall

Low

£875

Average

£1,580

High

£3,070

2-4 days

Chimney Breast Removal

Low

£1,050

Average

£1,755

High

£3,070

2-4 days

Underpinning

Low

£4,385

Average

£10,525

High

£21,925

2-4 weeks

Damp Proof Course

Low

£440

Average

£1,050

High

£2,195

1-3 days

New Build Garage

Low

£8,770

Average

£15,785

High

£26,310

3-5 weeks

Outbuilding or Garden Room

Low

£10,525

Average

£21,925

High

£43,850

3-6 weeks

Structural Steelwork (RSJ Installation)

Low

£875

Average

£1,580

High

£2,630

1-2 days

Patio or Decking Build

Low

£1,315

Average

£3,070

High

£6,140

3-5 days

Ad Slot -- In-Content 2

Regional comparison

How Cornwall Compares

Average cost of single storey extension across regions.

Cornwall
-12% £43,850
National Average
baseline £50,000
London
+24% £62,150

Local insights

What Affects Builder Costs in Cornwall?

The South West has a mix of housing styles, from Victorian and Edwardian semis to 1930s suburban developments and modern estates. In and around Cornwall, many properties in areas near Surrey and Kent vary in age and condition. Older properties with original features typically cost more for builder work due to additional preparation and access challenges.

The South West sits above the national average for trade costs, influenced by proximity to London and the generally higher cost of living. Labour rates in Cornwall are typically 12% below the UK average. Despite this, there's a strong supply of qualified builder professionals across the region. Prices can vary 30-50% between different tradespeople for the same job, so getting multiple quotes is essential.

What you pay for builder work in Cornwall depends on the complexity of the job, the materials used, and the condition of your property. Older detached and semi-detached homes often present more challenges that add to the cost. For larger jobs, expect to pay £43,850 to £122,780 for double storey extension in Cornwall. Coastal properties in the South West may face additional considerations that affect pricing.

When getting quotes in Cornwall, aim for at least three from different qualified professionals. Ask each one to visit and assess the work rather than quoting over the phone. A good builder will check the existing setup, identify complications, and provide a detailed cost breakdown. Be wary of quotes that seem significantly cheaper — they may be cutting corners on materials or quality. Always check qualifications, insurance and recent reviews.

Ad Slot -- In-Content 3

More services

Other Services in Cornwall

Explore costs for other services in the Cornwall area.

40 services — scroll to explore

Common questions

Frequently Asked Questions

Common questions about builder costs in Cornwall.

How much does a builder cost in Cornwall in 2026?
Single Storey Extension in Cornwall typically costs between £26,310 and £70,160, with the average being around £43,850. Prices vary depending on the scope of work, materials used, and the specific requirements of your property.
Are builder prices cheaper in Cornwall than London?
Yes. Cornwall builder costs are typically 12% below the national average, while London prices run around 24% above it. For single storey extension, you could save over £18,300 compared to the same job in London.
How do I find a good builder in Cornwall?
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 Cornwall?
The main factors are the scope and complexity of what you need, the options and products chosen, and local market rates. Cornwall rates are 12% below the national average. Getting multiple quotes is the best way to ensure a fair price.
Do builder prices include materials in Cornwall?
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.