Guide

How long does a loft conversion take?

Most loft conversions take between six and twelve weeks on site, with design and approvals adding time before work begins.

Typical build durations

On site, allow roughly the following for a standard project.

  • Rooflight conversion: 4 to 6 weeks
  • Dormer conversion: 6 to 9 weeks
  • Hip-to-gable with dormer: 8 to 11 weeks
  • Mansard conversion: 10 to 14 weeks

Before work starts

Design, structural calculations and building control submissions typically take four to eight weeks. If a planning application is required, allow a further eight to ten weeks for determination.

A typical week-by-week sequence

Scaffolding and roof opening come first, followed by structural steels and floor joists, then the dormer or gable structure, roofing and weatherproofing. Staircase, first fix plumbing and electrics, insulation, plasterboarding and finishing follow.

What causes delays

Prolonged bad weather, late material deliveries, unexpected structural findings once the roof is opened, and changes to the specification mid-build are the most common causes of overrun.

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