Budgeting is one of the first steps in planning a loft conversion. Costs can vary depending on the size, type, and finishes you choose. Here’s a breakdown of average loft conversion costs in 2025, plus the factors you need to consider.
Factors That Affect Cost
- Type of conversion (Velux, dormer, hip-to-gable, mansard)
- Size and complexity of the build
- Plumbing and electrical work
- Quality of finishes (bathrooms, flooring, built-in furniture)
- Location (London and the South East are more expensive)
Average Loft Conversion Costs in 2025
- Velux: £20,000–£30,000
- Dormer: £40,000–£60,000
- Hip-to-gable: £50,000–£70,000
Hidden Costs to Consider
- Planning application fees (if required, highly unlikely)
- Structural engineer fees
- Party wall agreements (if attached)
- Upgraded heating system if needed
- Additional insulation and soundproofing
How to Budget Wisely
- Always add 10–15% contingency for unexpected issues
- Ask for a fixed-price contract where possible
- Compare quotes from at least 2–3 experienced loft builders
Final Thoughts
A loft conversion is a significant investment, but it often pays for itself by boosting property value and saving you the expense of moving. With the right planning, it’s one of the smartest ways to add space and value to your home in 2025. Learn more about our Loft Conversion Services or explore our Loft Conversion Guides & Ideas to start planning.