Plan Then Build

Rear extension cost in North East

North East build costs run at 85% of the UK national average, across councils including Newcastle upon Tyne, Sunderland, Middlesbrough. A 20m² example at mid-range spec: £63,204–£85,512. Adjust the size and spec below for your project.

Permitted Development & Cost Checker

England only. Takes about a minute.

Rear extension cost by size and spec in North East

SizeBasicMid-rangePremium
15£32,919–£44,537£47,403–£64,134£67,886–£91,846
20£43,892–£59,383£63,204–£85,512£90,515–£122,461
30£65,838–£89,075£94,806–£128,268£135,772–£183,692

Does a rear extension need planning permission?

Council planning fees in North East

Each council sets its own fees and decision times. See your council’s page for the exact figures.

Rear extension cost in other regions

Cost bands refreshed quarterly from published 2026 UK cost guides.