Loft Conversions near you

Class B of Part 1 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 grants planning permission for the enlargement of a dwellinghouse consisting of an addition or alteration to its roof, subject to limits. The headline limit is volume: development is not permitted if the cubic content of the resulting roof space would exceed the cubic content of the original roof space by more than 40 cubic metres in the case of a terrace house, or 50 cubic metres in any other case. Original means as the house was first built, or as it stood on 1 July 1948, so a previous owner's dormer eats into your allowance.

The second limit is about the front of the house. Development is not permitted if any part of the enlargement would extend beyond the plane of the existing roof slope which forms the principal elevation of the dwellinghouse and fronts a highway. That is why rear dormers are common and front dormers are not: a rooflight sitting in the plane of the front slope is fine, a box projecting out of it is not.

Class B does not apply at all to a building containing one or more flats, or to a flat within such a building, and it does not apply on the designated land defined in article 2(3) - conservation areas, National Parks, Areas of Outstanding Natural Beauty, the Broads and World Heritage Sites. Nor does it apply where a planning condition or an article 4 direction has removed the right. All of this is England; Scotland, Wales and Northern Ireland have their own permitted development regimes and their own figures.

This is the provision that shapes a British loft conversion. Paragraph 2.21 of Approved Document B volume 1, the 2019 edition, says that where a new storey is added through conversion to create a storey above 4.5 metres, the full extent of the escape route should be addressed, and fire resisting doors of at least E 20 and partitions of at least REI 30 should be provided, including upgrading the existing doors where necessary. Where the layout is open plan, new partitions should be provided to enclose the escape route. In an ordinary two-storey house that means the stair becomes a protected stairway from the new floor all the way down to the front door, with fire doors onto it at every level.

Paragraph 2.23 offers an alternative for houses where that is not workable: sprinkler protection to the open-plan areas, a fire resisting partition of at least REI 30 and a door of at least E 20 separating the ground storey from the upper storeys with the door allowing loft occupants access to a first storey escape window, and cooking facilities separated from the open-plan area by construction of at least REI 30. Paragraph 2.22 deals with period houses: where replacing existing doors is undesirable because of their historical or architectural merit, the possibility of retaining and, where necessary, upgrading them should be investigated.

The floor matters as much as the doors. Paragraph 5.4 provides that where an additional storey is added to a two-storey single family dwellinghouse, new floors should have a minimum REI 30 fire resistance, any floor forming part of the enclosure to the circulation space between the loft conversion and the final exit should achieve a minimum of REI 30, and the existing first-storey construction should have a minimum rating of R 30 - with a relaxation on integrity and insulation where only one storey is added containing a maximum of two habitable rooms and the new storey has a maximum total area of 50 square metres. The Planning Portal adds that mains powered, interlinked smoke alarms will be needed within the stairway at each level.

A rooflight conversion changes nothing about the roof shape and simply lines and floors the existing space with windows set into the slope. It uses almost none of the volume allowance and is the only option that works on the front slope of a house facing a highway, but it needs a roof that already has the height and pitch to give usable floor area.

A dormer adds volume by projecting a box out of the slope, usually at the rear, and is what turns a standard terrace loft into a proper room with a flat ceiling. A hip-to-gable rebuilds the sloping end of a hipped roof as a vertical gable, which is how semi-detached and end-terrace houses gain width, and it is often combined with a rear dormer. A mansard reconstructs the whole roof at a steep pitch with a near-flat top and produces the most space of all, which is also why it is the one most likely to need planning permission rather than falling within Class B.

Which of these your roof will take is decided by three measurements taken before any design: the height from the existing ceiling joists to the ridge, the pitch of the roof, and whether the roof is cut-and-pitched with purlins or built from trussed rafters. A surveyor with a tape can answer in twenty minutes what a brochure cannot answer at all.

The big variables are the roof type and what has to happen to it, the amount of new structure needed to carry a floor, whether the conversion is rooflight, dormer, hip-to-gable or mansard, how much work the escape route forces onto the floors below, whether a shower room is going in and how far the drainage has to travel, where the new stair lands and what it costs you in the room below, and access for scaffolding and materials on a terraced street. A hip-to-gable with a rear dormer and an en-suite is several jobs at once; a rooflight conversion in a roof that is already tall is one.

LokalMatch is where the introduction happens. Describe the loft once - house type, roof, what you want up there, and your postcode - and conversion specialists covering your area will contact you. It costs homeowners nothing to use; the businesses pay for the enquiries they get. LokalMatch does not build anything, does not set prices, and does not vet, rank or recommend the firms that reply, so ask each of them to show you a completed conversion and the certificate that came with it.