Here is a straightforward comparison so you can see which one fits your home.
What is a dormer loft conversion?
A dormer is the most popular choice, and for good reason. It extends out from the sloping roof to create a box shape with a flat ceiling and a vertical wall, which gives you proper standing room and full-size windows.
Dormers work on a wide range of houses, terraced and semi-detached alike, and a rear dormer is often permitted development, so no planning application is needed. As a 2026 North London guide, a dormer runs £45,000 to £65,000. You can read more on our dormer loft conversion page.
What is a hip-to-gable loft conversion?
A hip-to-gable is designed for homes with a hipped roof, where the roof slopes inwards on the side as well as the back. This type replaces that sloping side with a flat gable wall, filling in the space and giving you a much larger, more usable room.
It suits semi-detached and end-of-terrace houses especially well, and it is often combined with a rear dormer for maximum effect. As a 2026 North London guide, a hip-to-gable is around £50,000 to £70,000.
What is a mansard loft conversion?
A mansard rebuilds one whole slope of the roof to a near-vertical angle, creating an almost full extra storey. It gives the most internal space and the most flexible layout of any loft type, which is why it is popular on period terraces where families want a real second floor.
The trade-off is cost and planning. A mansard changes the roof shape significantly, so it nearly always needs planning permission, and it is common in conservation areas. As a 2026 North London guide, a mansard starts at £60,000 to £80,000 and can go higher.
How do the loft conversion types compare?
Which loft conversion is right for you?
A quick way to narrow it down:
- If you want the best value and your roof already has decent height, a dormer is usually the answer.
- If you have a hipped roof on a semi or end terrace, look at hip-to-gable, often with a dormer added.
- If you want the largest possible space and are open to a planning application, a mansard is worth exploring.
In our North London loft conversions we help you weigh these up against your budget and your roof, so you are not paying for more than you need. Browse the full range on our loft conversions page.
Kev Construct Ltd holds a 9.67/10 rating from 50+ verified Checkatrade reviews, so you can see the results before you decide.
Get your free fixed-price quote and we will recommend the type that suits your home and budget.
FAQ
Which loft conversion adds the most space?
A mansard adds the most, because it rebuilds a whole roof slope to near vertical. It costs more and usually needs planning permission, but it can feel like a full extra storey.
Can I combine a hip-to-gable with a dormer?
Yes, and many homeowners do. A hip-to-gable opens up the side, and a rear dormer adds headroom and windows at the back, giving you a large, bright room.
Which type is cheapest?
A Velux (rooflight) conversion is the cheapest where head height allows, from around £30,000. Among the fuller options, a dormer usually offers the best balance of cost and space.
Not sure which type suits your roof? See every option on our loft conversions page, then book a free home visit and we will recommend the right one for your home and budget.
