How long does a loft conversion take?

Short answer: a standard dormer takes around 12 weeks on site, from the scaffold going up to handover. Velux conversions are quicker, at around 8 to 9 weeks, because there's no dormer or gable to build.

Before we start: design and approvals

Drawings, structural calculations, building control and any planning or party wall notices come first. If your loft comes under permitted development, they can be ready in as little as 4 to 6 weeks, depending on how busy the architect is. If you need planning permission, allow around 3 months on average for approval. We're sometimes booked several months ahead, so I'll give you a realistic start date at the survey.

On site: the five stages of a dormer

1. Floor structure: scaffold up, materials craned on, steels and new floor joists in, insulation and flooring laid.
2. Dormer: ridge beam in, dormer built and made weathertight, old roof removed, Velux windows fitted.
3. Stairs fitted: windows in, internal walls, insulation and plasterboard, then the stairwell opened and the staircase fitted.
4. Plastering: plastering, electrics and plumbing finished, bathroom fitted, Mick's finishing carpentry, tiling and gutters outside.
5. Completion: snagging, scaffold down, building control final inspection and a walkthrough with you.

All five stages together take around 12 weeks for a standard dormer.

What can slow things down

• Bad weather while the roof is open.
• Changes to the design once work has started.
• Waiting for special items such as made-to-match stairs or stained glass.
• Surprises in older houses, such as rotten timbers, which we'll always discuss with you first.

Real examples

• Richmond Road, Brighton (rooflight, flat): about 8 weeks
• Worthing (rear dormer): 12 weeks
• Poynter Road, Hove (L-shaped dormer): 12 to 14 weeks
• New Church Road, Hove (period house): 16 weeks