Question 1

How much does a loft conversion cost in the UK in 2026?

Accepted Answer

A UK loft conversion costs £25,000–£70,000+ in 2026. A Velux conversion costs £25,000–£35,000, a dormer £35,000–£50,000, a hip-to-gable £40,000–£55,000 and a mansard £45,000–£70,000. Adding an en-suite costs £4,000–£7,000 extra.

Question 2

Do I need planning permission for a loft conversion?

Accepted Answer

Most loft conversions fall under Permitted Development if they don't extend beyond the roof slope, aren't higher than the existing roof, use matching materials, and aren't in a conservation area. Dormers that face the highway usually need planning permission. Mansards almost always need planning permission.

Question 3

How long does a loft conversion take?

Accepted Answer

A Velux conversion takes 4–6 weeks. A dormer takes 6–8 weeks. A mansard or complex conversion takes 8–12 weeks. Most work is done externally until the staircase goes in, keeping disruption low.

Question 4

Will a loft conversion add value?

Accepted Answer

Yes — typically 10–20%, often more than the cost of the work. Adding a bedroom and bathroom to a 3-bed to make a 4-bed can add £40,000–£80,000 in value depending on location.

Question 5

What headroom do I need for a loft conversion?

Accepted Answer

You need at least 2.2m of standing headroom at the centre of the loft after the new floor and insulation are added. If you don't have it, a dormer or mansard can create it, at higher cost. Raising the roof is possible but expensive.

Question 6

Can I live in the house during the conversion?

Accepted Answer

Yes, in most cases. Scaffolding goes up outside and work happens through the roof until the staircase is installed near the end. Expect noise, dust and some disruption for 4–10 weeks. Many people move out for the final 1–2 weeks.

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