Attic Conversion Cost UK 2025
Calculate the cost to convert your attic into usable living space.
Loft, dormer, and full conversions • Updated January 2025
💡 Attic Conversion Cost Ranges
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Your Attic Conversion Estimate
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Typical Cost Breakdown
⏱️ Typical Timeline
Project duration will appear here.
📋 Planning Permission
Planning requirements will appear here.
📈 Added Property Value
A well-executed attic conversion typically adds £30,000 - £80,000 to property value, often more than the cost of conversion.
Attic Conversion Types
Basic Room-in-Roof (£15,000 - £25,000)
Strengthened floor, staircase, basic finish. Suitable for storage, occasional use, or office. No external changes to roof. Usually exempt from planning.
Velux Conversion (£25,000 - £40,000)
Full room with roof windows (Velux). Full insulation, electrics, heating. Great for bedrooms/offices where roof pitch allows. Usually planning exempt.
Dormer Extension (£35,000 - £55,000)
Extends out from the roof slope to create full headroom and vertical windows. Significantly more usable space. Usually needs planning permission in UK.
Hip-to-Gable + Dormer (£50,000 - £80,000+)
Converts hipped roof to gable end plus dormer. Creates maximum space. Common on semi-detached houses. Always requires planning permission.
Attic Conversion FAQs
Do I need planning permission?
Internal conversions with Velux windows are usually exempt. Dormers and hip-to-gable work typically need planning permission. We can advise on your specific situation.
Is my attic suitable for conversion?
Key factors: minimum 2.2m headroom (or ability to achieve with dormer), structurally sound roof timbers, and sufficient floor space. Most post-1960s houses are suitable.
How long does conversion take?
Basic: 3-4 weeks. Velux conversion: 4-6 weeks. Dormer: 6-10 weeks. Hip-to-gable: 8-12 weeks. Weather and planning can affect timelines.
Can I stay in the house during work?
Yes, for most conversions you can stay. There'll be some disruption but work is mostly contained to the attic and staircase area.
What about fire safety?
Building regulations require fire doors, smoke alarms, protected stairway, and escape windows. We ensure full compliance with Part B fire regulations.