Add space with a loft conversion

Hip to gable, dormer or structural – find out which loft extension is right for your home and maximise your space with expert advice from Real Homes Editor-in-Chief Michael Holmes

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A hip to gable loft conversion transformed this home (see the below for after image). 

If you live in a house with an unused loft, a conversion could be the most cost-effective way to add extra space. Loft rooms are suitable for almost any purpose, from bedrooms and bathrooms to a home office or playroom, gym or home cinema. If done well, with a full staircase, a conversion can provide a light-filled space with plenty of character.

Even if there doesn’t seem to be much space to convert in your roof, there is usually scope to move the roof timbers or water tanks and to increase the volume by adding dormer windows or changing the shape of the roof. If your loft is built using modern trusses, with a web of thin timbers, it can still be altered to create a useable space.

Planning permission often isn’t required for a loft conversion, as long as the design falls within the rules for Permitted Development (visit for details). If you want to get an idea of what is likely to be approved, look at what other people have achieved with similar properties in your area. Providing the work wasn’t done years ago, you’re likely to be able to do at least the same to your property.

Whether or not planning permission is required, all conversion work must comply with the Building Regulations, which builders have to follow. It is a false economy not to do so, as it will not be easy to sell on the property without proof that the work has been inspected and approved.

Maximise your space

Before altering your loft, you will need to consider if there is enough space to convert.

  • There are no rules on space or ceiling height for a loft conversion, other than for staircases, which need minimum clear headroom of 1.9m (1.8m at the edge) to meet the Building Regulations.
  • The minimum practical ceiling height for a loft room is 2.0m.
  • To work out how much useable space there is in your loft, draw a plan and mark a dotted line showing where there is 2.1m of clear headroom between the top of the joists and underside of the rafters. By the time the floor has been strengthened and built up, and the roof insulated, this will be the area with 2.0m of headroom.
  • You can add to the space by building dormer windows or making other alterations to the roof structure to increase the volume of the loft area.
  • Very low pitched roofs in properties built from the 1970s up to the present day may not provide enough space for a loft conversion, without being rebuilt at a steeper pitch.
  • If you live in a pre-1970s house, the roof timbers are likely to be easy to alter in order to create clear space. More contemporary housing with a truss roof structure made up of a web of thin timbers can be converted, but the work is more complicated. Using lightweight telescopic beams (visit for details) makes this easier and more cost-effective.
  • Cold water header tanks can be replaced by a smaller tank at a higher level, or removed and replaced with a mains pressure system that does not need any tanks, providing you have at least one-bar of water pressure in the local mains supply.

Choose the right one

In line conversion (£850-£1,250 per m²)

Dormer conversion (£950-£1,650 per m²)

Gable to gable conversion (£1,250- £2,250 per m²)

Hip to gable conversion (£1,250-£2,250 per m²)

Structural conversion (£1,350-£2,350 per m²)

Lowering ceilings (£1,550-£2,550 per m²)

Managing the project

Design and build contractors offer a service from design to completion, which can prove cost-effective as design fees are kept to a minimum and included in the package price. Once you have finalised the design, you won’t be able to shop around different builders to get the best price, but the benefit is that you will work with specialists.

The alternative is to hire an architect (visit or an architectural technologist (visit You can then put the project out to tender and find the best price from a builder of your choice. Architectural design fees can be disproportionate for a project like a loft conversion, so agree the cost before signing.

Whoever you choose, look at their previous work and ask for references. Use a formal contract and check the terms. Never pay in advance for any work unless it is put into an escrow account where funds will be held by a solicitor and only released to the builder when the work is completed.

If the conversion affects neighbours, you will need Party Wall agreements (visit For a leasehold property you may need freeholder consent.