Most people start out thinking they want “a loft conversion” and assume there’s only one kind. Then a builder comes round, looks up at the roof and starts talking about dormers, hips and gables, and suddenly it’s a lot less simple.
The good news is that there are only four main types, and your house narrows the choice down for you. The shape of your roof, how much headroom you’ve got and whether you’re in a conservation area do most of the deciding.
The short answer: most Sheffield terraces suit a rear dormer. Semis and detached houses with a sloping (hipped) side roof are often best with a hip to gable. If your loft already has good headroom and you only need one room, a Velux conversion is the cheapest route. Mansards give you the most space, but they cost the most and usually need planning permission.
Here’s how each one works.
First, check your loft has enough height
Before choosing a type, it’s worth grabbing a tape measure. Go into the loft and measure from the top of the ceiling joists to the underside of the ridge beam (the highest point of the roof).
As a rough guide, builders look for around 2.2m. If you’ve got that, all four types are usually on the table. If you’re well short, a Velux conversion probably won’t work on its own, and you’ll be looking at a dormer or another type that adds height.
Don’t worry if the number’s borderline. There are ways round it, and a builder can tell you pretty quickly once they’ve seen the space.
Velux (rooflight) loft conversion
This is the simplest option. The roof stays exactly as it is, and windows are fitted into the existing slope. Inside, the loft gets insulated, boarded, plastered and fitted with a staircase.
Good for: homes that already have decent headroom, and anyone who wants the job done with as little disruption as possible.
Typical cost in Sheffield: from around £25,000.
Planning permission: rarely needed, as the outline of the roof doesn’t change. You’ll still need building regulations approval.
The catch: you only get the space that’s already there. Because the ceiling follows the roof slope, a fair bit of the floor area ends up with low headroom. Fine for a bedroom with the bed tucked under the eaves. Less good if you want a bathroom with a shower you can stand up in.
Dormer loft conversion
A dormer is a box-shaped structure that sticks out from the sloping roof, usually at the back of the house. It creates a section of full-height ceiling and a proper vertical window, which makes the room feel far more like the rest of the house.
It’s the most popular type in the UK, and it’s the one we fit most often across Sheffield. That’s largely down to the city’s housing. The stone and brick Victorian terraces you’ll find in places like Walkley, Crookes, Heeley and Nether Edge are ideal for a rear dormer.
Good for: terraced, semi-detached and detached houses. It’s often the best balance of cost and extra space.
Typical cost in Sheffield: from around £35,000.
Planning permission: a rear dormer usually falls under permitted development, which means you don’t need full planning permission, as long as it stays within the volume limits (40 cubic metres for terraced houses, 50 for others) and meets the other rules. Front dormers usually do need planning permission.
Worth knowing: a lot of Sheffield terraces have a rear outrigger, the narrower two-storey section that sticks out at the back. On these, you can build an L-shaped dormer, which runs across the main roof and over the outrigger too. It can give you space for two bedrooms and a bathroom. It’s a bigger job though, and it can push past the permitted development allowance, so it’s worth checking early.
If you live in a terrace, our terraced house loft conversion guide goes into more detail.
Hip to gable loft conversion
Plenty of semis and detached houses have a “hipped” roof, where the side of the roof slopes down as well as the front and back. It looks tidy, but it eats into loft space, as the sloping side leaves you with a narrow, triangular loft.
A hip to gable conversion replaces that sloping side with a vertical wall (the gable), so the roof runs straight across. The loft suddenly gets a lot bigger, and there’s room for a staircase that doesn’t feel like it’s been squeezed in.
Many homeowners pair it with a rear dormer to get as much space as possible.
Good for: semi-detached and detached houses with a hipped roof. You’ll see plenty of these in the 1930s semis around Sheffield’s suburbs.
Typical cost in Sheffield: upwards of £50,000.
Planning permission: often covered by permitted development if it stays within the volume limits and the house isn’t in a conservation area. If you add a big rear dormer as well, the combined volume adds up quickly, so it’s worth checking.
The catch: it’s a bigger structural job, so it takes longer and costs more. On a semi, the new gable also needs to look right alongside your neighbour’s roof, which is something to think about if they haven’t done the same.
We’ve written more about this in can you have a loft conversion in a semi-detached house?
Mansard loft conversion
A mansard changes the shape of the roof altogether. The back slope (and sometimes the front) is rebuilt almost vertically, at an angle of around 72 degrees, with a flat top. Windows sit in small dormers within the new slope.
The result is the most usable space of any loft conversion. It’s close to adding a whole extra storey.
Good for: terraces and townhouses where you want as much room as possible, and where the planners are happy with the look.
Typical cost in Sheffield: usually over £60,000.
Planning permission: usually needed, because it changes the roof so much.
The catch: it’s the most expensive and takes the longest. They’re less common in Sheffield than in cities like London, and whether the council will approve one depends a lot on your street.
Quick comparison
| Type | Typical Sheffield cost | Extra space | Planning permission | Best suited to |
|---|---|---|---|---|
| Velux (rooflight) | From £25,000 | Low | Rarely needed | Lofts with good existing headroom |
| Dormer | From £35,000 | Good | Usually not, for rear dormers | Terraces, semis, detached |
| Hip to gable | From £50,000 | Very good | Often not, within limits | Semis and detached with a hipped roof |
| Mansard | £60,000+ | The most | Usually needed | Terraces and townhouses |
Costs are starting points and depend on the size of the loft, the finish you choose and what’s involved structurally. Our loft conversion cost guide breaks this down further.
So which one should you choose?
A few questions usually settle it.
What type of house do you have? Terraces tend to go dormer (or L-shaped dormer). Semis and detached houses with a hipped roof tend to go hip to gable, often with a dormer at the back.
How much space do you need? A single bedroom or study might only need a Velux conversion. A main bedroom with an en-suite almost always needs the extra height a dormer gives. If you’re wondering what’s realistic, see how many rooms you can get from a loft conversion.
Are you in a conservation area? Sheffield has a good number of them, and part of the city sits in the Peak District National Park. In these areas you’ll need planning permission for most roof changes, and the council may prefer less visible options such as rear dormers or rooflights. Our guide to planning permission for Sheffield loft conversions explains what to check.
What’s your budget? There’s a big jump between a Velux conversion and a mansard. It’s worth knowing your ceiling (so to speak) before you start getting quotes.
Things that apply whatever you choose
- Building regulations: every loft conversion needs building regulations approval, covering things like fire safety, stairs, insulation and the strength of the floor.
- Party wall agreement: if you live in a terrace or semi, work on the shared wall usually means serving notice on your neighbours under the Party Wall Act.
- Stairs: the new staircase has to fit somewhere on the floor below, often over the existing one. It’s easy to overlook, and it can shape the whole design.
- Scaffolding: most conversions need it, apart from some Velux jobs. See do I need scaffolding for a loft conversion?
Not sure which type suits your home?
It’s hard to tell from a guide alone. Every roof is a bit different. We’ll come out, have a look and talk you through which options make sense for your house and your budget. For a no-obligation quote for a loft conversion in Sheffield, get in touch.