How much does a loft conversion cost?

Short answer

A rooflight loft conversion typically costs £30,000–£45,000 for a typical rooflight conversion, a rear dormer £48,000–£68,000 for a typical rear dormer with en-suite, a hip-to-gable £55,000–£78,000 for a hip-to-gable with rear dormer and a mansard £65,000–£95,000 for a typical rear mansard, including VAT. London prices run around 30% higher.

What is included in the price?

Our guide ranges include structural steel and floor joists, the dormer or roof alterations, windows, staircase, fire safety upgrades, insulation, electrics, plastering and building control. An en-suite is included in the dormer and hip-to-gable ranges.

Extras that change the cost

A second bathroom or a larger en-suite.
Built-in eaves storage and wardrobes.
Juliet balconies or larger glazing.
Party wall surveyor fees on terraces and semis.
Moving water tanks and upgrading the heating system.

Does a loft conversion add value?

An extra bedroom and bathroom often add value, but it depends on local prices. Check recent sales on your street before deciding how much to spend.

Next step

Try our guide price tool for an instant range, then book a free survey for a fixed quote.

Sources and further reading

GOV.UK: Approved Documents

This guide is general information, not legal or tax advice. Rules change and depend on your property; we confirm what applies to your project at the survey.