How Much Does a Loft Conversion Cost in 2026?
A loft conversion is one of the most cost-effective ways to add a bedroom or office space. In 2026, UK costs range from £20,000 for a simple Velux conversion to £65,000+ for a full mansard.
Get a Personalised Estimate
Tell our AI about your specific project and get an accurate price range in seconds — free, no signup required.
Get My Free EstimateCost Breakdown by Tier
Simplest option — adds windows to the existing roof slope without changing the structure.
Extends the roof to create a flat-roofed box dormer. The most popular choice for extra headroom.
Major structural alteration. Maximum space gain, often requires planning permission.
Factors That Affect the Cost
- Type of conversion (Velux, dormer, mansard, hip-to-gable)
- Existing roof structure and head height
- Staircase design and placement
- En-suite bathroom addition
- Structural reinforcement requirements
- Party wall agreements (terraced/semi-detached)
Regional Price Variations
Loft conversions in London and the South East average 20–30% more than the rest of the UK due to higher labour rates and property prices making larger conversions more worthwhile.
Frequently Asked Questions
Do I need planning permission for a loft conversion?
Most loft conversions fall under Permitted Development rights. However, mansard conversions, conservation areas, and flats typically require planning permission.
How long does a loft conversion take?
Typically 6–12 weeks. Velux conversions are the quickest (4–6 weeks), while mansard conversions take 10–12 weeks.
Will a loft conversion add value to my home?
A loft conversion typically adds 15–20% to your property value — often more than the cost of the conversion itself.
Is my loft suitable for conversion?
Most lofts with a ridge height of at least 2.2m can be converted. A surveyor can confirm suitability and recommend the best option.
Find Local Tradespeople
Browse trusted, reviewed tradespeople in your area ready to quote on your project.
Find Tradespeople Near Me