Loft conversion types explained: dormer, hip to gable and mansard
A loft conversion is one of the smartest ways to add space to a home without losing any of your garden or moving house. But not all loft conversions are the same, and the right type for your home depends on your roof shape, the space you want to create and your budget. This guide explains the four main types in plain English, what each one costs, and how to work out which is right for you.
Roof light conversion
The simplest and most affordable option, a roof light conversion keeps the existing roof shape exactly as it is and adds windows, such as Velux units, set into the slope of the roof. Because the structure barely changes, it is the least disruptive and cheapest route, and it rarely needs planning permission. The catch is that it only works well where there is already plenty of head height in the loft, so it suits properties with a steep, tall roof.
Dormer conversion
A dormer conversion is the most popular choice for many homes, and for good reason. It extends outward from the slope of the roof to create a box shaped structure, which adds both floor space and valuable head height. Dormers work on a wide range of properties, offer a good balance of cost and space, and often fall within permitted development. If you want a comfortable double bedroom with an en suite in the loft, a dormer is frequently the answer.
Hip to gable conversion
This type suits detached and semi detached homes that have a hipped roof, meaning a roof that slopes on the side as well as the front and back. A hip to gable conversion extends the sloping hip out to a vertical gable wall, which significantly increases the internal volume of the loft. It is often combined with a rear dormer to create a generous amount of space, and it can transform an awkward, cramped loft into a proper room.
Mansard conversion
A mansard is the most substantial type of loft conversion. It changes the structure of the roof to create an almost vertical rear wall and a nearly flat roof, which maximises both space and head height. Mansards produce the most dramatic increase in usable room and can suit period properties and terraced houses, but they are the most involved to build and usually the most expensive. They almost always require planning permission because of the significant change to the roofline.
How much do loft conversions cost?
Costs vary with the type of conversion and the size and specification of the finished space. The ranges below are a useful guide for budgeting.
| Project | Indicative cost |
|---|---|
| Roof light conversion | £28,000 to £45,000 |
| Dormer conversion | £40,000 to £65,000 |
| Hip to gable conversion | £45,000 to £70,000 |
| Mansard conversion | £55,000 to £80,000 |
Figures are indicative UK ranges to help you budget and are not a quote. Actual costs depend on size, specification and site conditions.
Do I need planning permission?
Many loft conversions are permitted development, but mansards and some dormers do need planning permission, particularly on the front of a property or in a conservation area. Every loft conversion needs building regulations approval because of the structural work, staircase and fire safety requirements. Our guide on planning permission explains this in more detail.
Preparing for your loft conversion
A little preparation makes a loft conversion run more smoothly. Think early about how the new space will be used, as a bedroom, office or bathroom, because this affects the layout, the wiring and the plumbing. Consider where the new staircase will go, since this is one of the biggest design decisions and can affect the room below. It is also worth planning for storage, as converting the loft removes the space many people use for boxes and suitcases, so built in eaves cupboards are a popular addition. Finally, think about heating, insulation and ventilation from the outset, as a well insulated loft is comfortable all year round and cheaper to run. We help you work through all of these decisions during the design stage.
Which type is right for your home?
The best way to find out is a free assessment. The key factors are the available head height, the shape and structure of your roof, and where a new staircase can go. We look at all of this and recommend the option that gives you the best space for your budget. You can explore the full service on our conversions page, see finished projects on our case studies page, and read our advice on choosing a builder before you start. We work across Solihull, Knowle, Dorridge, Shirley and the wider West Midlands.
Call 07393 194 336Get a free quote