DOT Types of Loft Conversion Explained
Velux, rear dormer or hip-to-gable: what each one does to your roof, what it’s best for, and what it costs with us. All prices are plus VAT.
Which type of loft conversion do I need?
It depends on what you want to use the space for.
- Just want more light, and the loft already has enough space? Add Velux windows.
- Want a bedroom? A rear dormer gives you lots of light and more headroom.
- Want a larger bedroom, maybe with an en-suite? A hip-to-gable lifts a whole side of the roof. It costs more, but gives you the most space.
Velux windows
Best for: a loft that already has enough space, where you just want more light. Velux windows are fitted into the existing roof slope, each with the right flashing kit to match your tiles. Adding them to your existing roof starts from about £6,000. If the whole roof needs replacing at the same time, it’s more like £20,000.
- Cheapest option
- Fastest to build
- No change to exterior look
- Doesn’t add head height
- Needs good existing head height
Rear Dormer
Best for: turning the loft into a bedroom. A box with straight walls is built out from the back of the roof, giving you lots of light and more headroom across most of the loft. Our Leicester job, a new roof with Velux windows and a small rear dormer with a rubber flat roof, came in at about £38,000. See the case study.
Full guide to dormer loft conversions →
- Big space & head-height gain
- Most versatile, good value
- Suits most house types
- Changes rear roofline look
- Must stay within PD volume limits
Hip-to-Gable
Best for: a larger bedroom, maybe with an en-suite. The sloping end of the roof is lifted into a straight gable wall, so you can stand up across that whole end of the loft. It costs more, but it gives you the most space. We take the tiles off, put in the new structural beams and rebuild the roof with the new gable. Our Little Haywood hip-to-gable, with a small rear dormer and a whole new roof, cost about £32,000 and took about 10–12 weeks. See the case study.
Full guide to hip-to-gable conversions →
- Big space gain at gable end
- Great paired with a dormer
- Only suits homes with a hip roof
- Changes side profile of the house
How do the loft conversion types compare?
| Type | Cost (+ VAT) | Time on Site | Best For |
|---|---|---|---|
| Velux windows | From £6k (£20k with new roof) | Depends on the job | More light |
| Rear Dormer | £32k–£58k | 8–12 wks | A bedroom |
| Hip-to-Gable | £32k–£65k | 8–12 wks | A larger bedroom, maybe with en-suite |
Which type is right for my house?
Start with what you want the space for. If it’s just more light in a loft that’s already big enough, go for Velux windows. If it’s a bedroom, a rear dormer is usually the answer. If you want a bigger bedroom, maybe with an en-suite, and you have a semi or detached house with a sloping end to the roof, a hip-to-gable gives you the most space.
We’ll look in your loft at a free visit and tell you honestly which makes sense, including if the loft is too small to be worth converting. See our loft conversion cost guide for what’s included and how we price.
Loft type FAQs
Which type of loft conversion is best?
It depends on what you want the space for. Velux windows for more light, a rear dormer for a bedroom, and a hip-to-gable for a larger bedroom, maybe with an en-suite.
How much does each type of loft conversion cost?
With us, Velux windows start from about £6,000 (about £20,000 if the whole roof is replaced), a rear dormer is £32,000 to £58,000, and a hip-to-gable £32,000 to £65,000, all plus VAT.
Can I combine two types?
Yes — a hip-to-gable is very often combined with a rear dormer on semi-detached and detached houses, which gives you the most space.
Which types need planning permission?
Velux windows, rear dormers and hip-to-gables can usually go under permitted development, within the volume limits. A dormer on the front of the house, or a mansard, is the most likely to need full planning. See our loft planning guide.
Related pages
Not sure which type suits your loft?
We’ll assess your roof at a free site visit and recommend the right option.