Question 1

How much does a single-storey rear extension cost in London?

Accepted Answer

A standard single-storey rear extension in London typically costs between £40,000 and £90,000 in 2026 depending on size, finish and groundworks. Our calculator gives you an instant ballpark and a written estimate after a free site visit.

Question 2

Is the cost calculator free?

Accepted Answer

Yes — the Rankitt instant cost calculator is completely free with no obligation. You only commit when you sign a written quotation after a site visit.

Question 3

How accurate is the instant quote?

Accepted Answer

The calculator uses 2026 London market data and our last 200 projects to produce a ballpark ±15%. A detailed estimate requires a site visit and full drawings — RCB will provide that free within 5 working days.

Question 4

What is included in the price?

Accepted Answer

The ballpark includes labour, materials, project management, scaffolding, skips, building control fees and statutory inspections. Excludes planning fees, party-wall surveyor fees, structural engineer drawings and second-fix materials (which clients supply).

Question 5

How quickly can RCB start the project?

Accepted Answer

Once a quotation is signed and a 5% deposit is paid, we typically mobilise within 4–8 weeks for extensions and 2–4 weeks for refurbishments. Smaller works can often start sooner.

What type of project are you planning?