Plan Then Build

Loft conversion cost in South East

South East build costs run at 115% of the UK national average, across councils including Brighton and Hove, Oxford, Reading. A 20m² example at mid-range spec: £85,512–£115,692. Adjust the size and spec below for your project.

Permitted Development & Cost Checker

England only. Takes about a minute.

Loft conversion cost by size and spec in South East

SizeBasicMid-rangePremium
15£44,537–£60,256£64,134–£86,769£91,846–£124,262
20£59,383–£80,342£85,512–£115,692£122,461–£165,683
30£89,075–£120,513£128,268–£173,538£183,692–£248,524

Does a loft conversion need planning permission?

Council planning fees in South East

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

Loft conversion cost in other regions

Cost bands refreshed quarterly from published 2026 UK cost guides.