If you’re looking to add space and value to your home with a loft conversion, you’ve probably come across two popular options: dormer and mansard conversions. Both have their own advantages and architectural features, and the choice between them will depend on your budget, the style of your home and how much space you want to gain.
In this guide we’ll go through what each involves, the differences and how they compare in terms of benefits and cost.
What Is a Dormer Loft Conversion?
A dormer loft conversion involves extending your existing roof upwards to create a box shaped structure that sticks out from the sloping roof. This type of conversion increases the head height and usable floor space in your loft. Dormers have windows to let in natural light and are one of the most popular types of loft conversions in the UK.
There are several types of dormers:
- Flat-roof dormers – the most common, with the most internal space.
- Gable-fronted (or doghouse) dormers – a pitched roof dormer that adds character.
- Hip roof dormers – with a sloping roof on three sides, ideal for detached homes.
Dormer conversions are often the most straightforward and cost effective option, especially for properties with existing roof space.
What Is a Mansard Loft Conversion?
A mansard loft conversion is more structurally dramatic. It involves altering the entire slope of one side (or both sides) of the roof, replacing it with a steep almost vertical wall and a flat roof on top. This style is named after the French architect François Mansart and is particularly common in London and other urban areas with terraced housing.
Mansard conversions require more construction work and almost always need planning permission. But they create a lot of internal space and can make your loft feel like a full additional storey.
Differences Between Dormer and Mansard Conversions
The main difference between the two, is the level of structural change.
Dormer conversions involve a minor extension of the existing roof, adding a box shaped structure with windows. Mansard conversions involve a full scale alteration of the roof shape, replacing the slope with a much steeper angle and a flat top. As a result mansard conversions offer much more internal headroom and floor space. However mansard conversions almost always require planning permission whereas many dormer projects can be done under permitted development rights. Dormers are quicker and cheaper to build, mansards take longer due to the scale of the work involved and often have a greater architectural impact on the property.
Dormer vs Mansard Loft Conversions
Dormer benefits:
- Cheaper and quicker to build
- Often falls under permitted development rights
- Great for extra light and headroom
- Flexible design – suitable for bedrooms, offices or bathrooms
Mansard benefits:
- Most living space of any loft conversion style
- Full height room that feels like an extra room in your home
- Suitable for period properties and urban areas
- Adds most value to your property
Cost Comparison: Dormer vs Mansard Loft Conversions
While costs vary depending on your location, property type and design choices here’s a rough guide:
- Dormer Loft Conversion: £30,000-£50,000
- Mansard Loft Conversion: £45,000-£70,000+
* Mansard conversions are more expensive because they involve more structural work and require planning permission. But they can also offer greater return on investment by increasing the usable floor area and overall property value.
Choosing between a dormer and mansard loft conversion comes down to your goals, budget and the character of your property. If you want a quick and cost effective way to gain space then a dormer might be the way to go. But if you want to transform your loft into a full height room then a mansard conversion could be worth the investment.
Need advice tailored to your home? Get in touch with us today to discuss your options and which conversion is best for you.
