Can you do a loft conversion for 20k?
Not in London. A basic Velux loft conversion with no structural roof alteration starts at around £45,000 in Fulham, and a rear dormer with an en-suite is £55,000 to £85,000. £20,000 does not cover the structural floor, staircase and fire safety work a legal conversion requires.
A loft conversion is not a room decoration exercise — it is a structural project. The existing ceiling joists are not designed to carry floor loads, so new steel beams and a new floor structure are needed. A compliant staircase must be built, which usually means losing space on the floor below. Fire regulations require a protected escape route, fire doors throughout and mains-linked alarms. Those items alone exceed £20,000.
The cheapest genuinely compliant conversion is a Velux or rooflight conversion, which keeps the existing roof shape and adds windows in the roof plane. In Fulham that is around £45,000 to £55,000. It only works where there is already sufficient headroom, since it adds no volume.
You may see £20,000 figures for 'loft boarding' or 'loft rooms'. These are not conversions and cannot lawfully be used as bedrooms — they have no building control sign-off, no compliant stair, no fire protection. They will be flagged on a survey when you sell, and a buyer's solicitor will ask for a completion certificate that does not exist. The value they add is nil or negative.
If the budget is genuinely £20,000, better uses exist. Reconfiguring the existing first floor, adding a well-designed en-suite, or improving insulation and storage in the loft as loft space all deliver real benefit within that figure — without creating a room you cannot legally call a bedroom.
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