Lofty aspirations: utilising the roofspace

To most people the reality of loft living is a long way from Urban Splash's model of urban regeneration. A large proportion of planning applications simply relate to the conversion of a dusty attic space into an extra bedroom or two. It seems that top floor domestic extensions are more manageable investments than the chic warehouse alternatives.

In this exclusive extract from Shortcuts: Book 1 by Austin Williams,
we discuss the planning and building control implications of
domestic loft conversions.
 

Planning considerations

Kate Barker's Review of Land Use Planning, published in 2006, addressed the need to build substantial volumes of new housing by freeing up development potential. Her recommendations include not only relaxing controls on building on the greenbelt, but also relaxing planning powers more generally. The report said that "planning resources should be able to focus more on the larger-scale applications, rather than the small-scale permissions which have little impact on the wider public interest. To achieve this, the principle of the Householder Development Consent Review (that permitted development rights for householders should be extended based on an 'impact' principle) should be rolled out to minor applications."

These "minor applications" weren't spelled out. However, Barker explicitly recommended reducing planning powers over domestic and commercial microgeneration proposals, and her words have been interpreted as extending permitted development rights to make it easier to build on, convert and extend domestic roofs. The government has generally accepted the recommendations in her report. As a result, ministers agreed that, from 1 October 2008, loft conversions are allowed without planning consent, provided that they meet certain conditions. For instance, they must not extend beyond the plane of the existing roof slope on the principal elevation fronting the highway. (Note: Work to properties more than 20 m from a highway are permitted anyway, provided that they also satisfy all other criteria.)

Essentially, this implies that a traditional rooflight with raised jambs for flashing, taking it above the plane of the roof, will not be permitted. But bear in mind that planning departments have discretionary powers, and decisions may vary between authorities.

Other criteria that have to be satisfied before a loft may forego planning consent are:

• The new volume must not exceed an additional 40 m³, for terraced houses (internal measurements)
• The new volume must not exceed an additional 50 m³, for all other dwellings
• No extension may extend above the highest part of the roof
• The materials must be similar in appearance to the existing house
• There should be no verandas, balconies or raised platforms
• Side-facing windows must be obscure-glazed and any opening portion must be at least 1.7 m above the internal floor level
• There should be no roof extensions in designated areas (the Broads, national parks, areas of outstanding natural beauty, conservation areas and world heritage sites)
• Roof extensions, apart from those rising from hip to gable, must be at least 20 cm from the eaves.

Recent surveys indicate that more and more people are considering extending their family home rather than suffering the pain and expense of moving to another property. Ex-housing minister Caroline Flint noted that, as the economy slows, these new planning rules will "make a real difference to already-stretched family finances, making home improvement an increasingly attractive option." Given the recent collapse of credit and the fall in the housing market, people seem not only to be moving less, but also building less.

The planning procedures for small-scale developments should become less onerous, implying that homeowners could bypass local authority planning departments for schemes comprising a loft extension (or a conservatory). The decision to liberalise permitted development for loft extensions omits the original recommendations of the Barker Review that only those extensions/conversions which have a "non-marginal third-party impact" will evade planning consents. Under the new legislation, no such consideration need be given. However, it is still advisable that one gains consent from one's neighbours – and of others in the vicinity who may be affected by the work – prior to proceeding, since there still remains the possibility of them complaining.

Currently, if the loft conversion is a permitted development, the complaint will come to nought, as the application is dealt with on purely legal (rather than aesthetic) grounds. This has often caused disputes between neighbours, and Barker's more open forum of neighbour notification is intended to overcome the perceived underhandedness of the current system.

Even though there may be some people who will prefer to submit applications in the traditional way, the government estimates that the proposals will reduce 'minor' planning applications by around 80,000 per year. In 2007, around 340,000 domestic planning applications were submitted (approximately 50 per cent of all applications) of which about 90 per cent were approved.

Even without the new legislation, loft conversions have only rarely required planning permission. For example, new-build work to a detached or semidetached property would have had to have exceeded 50 m³ or 15 per cent of the original volume, whichever is greater (the corresponding values for a terraced property are 40 m³ or 10 per cent of the original house volume).

Fire safety

Until April 2007, when Approved Document B (AD B) Fire Safety came into force, if a design incorporated an open-plan loft access, then all doors to habitable rooms off the stairwell had to be provided with self-closers. This is no longer the case, but the government is urging homeowners to keep closed all doors that protect the escape route, especially at night.

Under the new Approved Document B provisions, a two-storey house with a loft conversion is treated as a three-storey property, requiring escape via a protected stair. Inner rooms are not permitted in the converted loft area, and inner rooms on lower storeys must have (or be provided with) egress windows, which may be lockable to protect children provided that they have a safe release mechanism. Existing doors accessing the existing staircase must be replaced with fire-resisting doors to ensure that there is a fire-protected route to the final ground-floor exit; the exception is doors to non-habitable rooms such as bathrooms and cloakrooms. If it is considered undesirable to replace existing doors, e.g. if they are of historical or architectural merit, it may be possible to retain them or upgrade them to an acceptable standard. Internal glazing along protected escape routes within fire-resisting structures must also be fire-resisting. Self-closing devices are not required on fire-resisting doors.

New rooms in a domestic loft space should be design/risk assessed in accordance with CDM 2007: Regulation 11. In lofts where the floor is less than 4.5 m above ground level and where it is not feasible to provide a protected stair, the loft floor should have 30 minutes fire resistance (FR30) and have a rooflight or similar to provide secondary escape. Windows or rooflights for emergency egress from a loft room (or from a second floor room where the loft creates a third storey) should meet the following criteria:

• Width and height: not less than 450 mm
• Clear openable area: not less than 0.33 m²
• Bottom of openable area: not more than 1100 mm above finished floor level

The window or rooflight should enable the person escaping to reach a place free from danger from fire and, especially where the floor is greater than 4.5 m above external ground level, should be in a part of the roof that can be reached by somebody providing outside assistance using a ladder.

Shortcuts provide an eclectic mix of at-a-glance guides to the minefield of regulations, new materials, and technologies that  confront building designers today. Comprising hand-drawn sketches, technical drawings, and punchy articles, each Shortcut takes you right to the heart of a key topic in architecture and construction, presenting a wealth of invaluable information in an accessible and lively way.

Shortcuts: Structure and Fabric by Austin Williams focuses on issues to do with the structure and fabric of buildings. Grouped into four main subject areas, the Shortcuts range from rainscreen cladding to fire protection, from lofts to lifts, and from LEDs to SUDS.

To order a copy of this book, please visit RIBA Bookshops.

Copyright RIBA Publishing March 2009.

Additional publications and services

Available to buy now from RIBA Bookshops:

Shortcuts: Sustainability and Practice

NBS Domestic Specification (2nd Edition)

Also available:

NBS Building Regulations

Related NBS information:

Articles:

• Fire! A synopsis of Approved Document B

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