- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 23 Dec 2019
Loft conversions have been said to increase the value of a home by up to 20%, and can add up to 30% more living space to a house. This valuable area is an excellent development opportunity and can offer a useful alternative to moving house in most instances.
 Types of loft conversion
A Dormer is a structure that is attached to the roof to create additional headspace and a window that juts out from the roof, rather than working within the pitch like a Velux window. Dormer loft conversions are among the most popular because of the additional headspace that they offer.
Velux loft conversions take their name from the brand of roof window, and work with the pitch of the roof to simply add skylights rather than making drastic changes to the exterior of the house or the pitch of the roof. These are also popular since they rarely require planning permission and can often be completed in less time than other loft conversion due to the minimal changes to the roof.
Gable End loft conversions change the shape of the roof to create upright walls on one or both ends of the building. These offer a lot of additional headroom and usable floorspace compared to Velux and Dormer loft conversions, but take longer to complete and are usually more expensive due to the extensive work required.
Mansard loft conversions make the most drastic changes to a house, but add the most space. The roof pitch is altered to create a roof that points out at 72 degrees or more, so the roof has three walls rather than just two. Planning permission is often required for this type of loft conversion.
For more information, see Mansard roof.
Building regulations approval is required to convert a loft into a liveable space. Regulations will ensure that the floor is structurally sound, the roof is stable, the stairs are safely designed, there is reasonable sound insulation, and there is safe exit in case of fire.
For more information, see Key regulations for loft conversions.
 Planning permission for loft conversion
In many instances, loft conversions can be completed as Permitted Developments, which do not require planning permission. However, if the plans fall outside of these limitations then planning permission will be required. Planning permission may also be necessary if the house is in a conservation area or a listed building.
- Be no larger than 40 cubic meters in a terraced house, or 50 cubic meters in a detached or semi-detached house.
- Not extend beyond the existing plane of the roof.
- Be build in materials that are similar in appearance to the existing house.
- Not have any verandas, balconies, or raised platforms.
- Be set as far back as reasonably practicable.
- Not overhand the outer face of the wall of the original house.
 Related articles on Designing Buildings Wiki
Featured articles and news
Architectural Technology Studio 3
Construction Industry Advisory Committee CONIAC
The real impact of late payment.
How to tell which infrastructure projects will work.
The government announces the biggest change in building safety for a generation.
Key messages from the UN COP 25 conference.
Reducing the risks of buying off-plan
A lighthouse history from Eddystone to Fastnet. Book review.
Telling the story of the Government Code and Cipher School.
Are you an experienced writer with a practical understanding of the industry?
Hagia Sophia, Istanbul.
New Dwelling House at Grange View.
The causes of sinkholes.