It not normally necessary to apply for planning permission to convert a loft space into living accommodation, unless the roof space is extended, altered, or exceeds specified limits and conditions. However, you must seek prior approval for building regulations.
A home loft conversion will be considered a ‘permitted development’ (i.e, it doesn’t require planning permission) if:
- A maximum volume of 40 cubic metres additional roof space (terraced houses)
- A maximum volume of 50 cubic metres additional roof space (detached and semi-detached houses)
- The extension must be within the plane of the existing highway-fronting roof slope of the principal elevation
- The extension cannot be higher than the highest part of the roof
- Materials must have a similar appearance to the existing house
- Verandas, balconies or raised platforms are not allowed
- Side-facing windows must be obscure-glazed
- Openings must be at least 1.7m above the floor
- Roof extensions are not ‘permitted development’ in listed buildings or designated areas, including: national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.
- Other than hip to gable extensions, roof extensions must be set back as far as practicable, and at least 20cm from the original eaves
- The roof enlargement cannot overhang the outer face of the wall of the original house
Rember that any previous enlargement of the roof space must be included within these volumes. Check that a previous owner has not already created additional space which should be included.
These rules are for terraced, semi-detached and detached houses. There are different rules covering other types of property. There are areas where there may be a planning condition, Article 4 Direction or other restriction that limits permitted development rights.
The government has published a full technical guide for homeowners on its website: Gov.UK
Building regulations approval is required to convert a loft or attic into a liveable space.
The following rules apply to an existing house which is no more than two storeys high, for making alterations to the loft space. There may be further requirements for alterations to a flat, apartment, maisonette, or houses over three storeys.
Building regulations will ensure that:
- the structural strength of the new floor is sufficient for purpose
- the stability of the structure (including the existing roof) is not endangered
- there is a safe route for escape from fire
- there is safe access via stairs to the new floor
- sound insulation is sufficient between the new conversion and existing rooms below
Making loft space more accessible, changing it to living accommodation by installing stairs and lining the walls / rafters, or improving storage by boarding out the loft space, are all likely to require a Building Regulations Application. This applies whether you just wish to enhance your storage facilities or to increase the living space of the home.
Contact Building Control before you start work to discuss your proposal and seek further advice. You must also find out whether the work you intend to carry out falls within The Party Wall etc. Act 1996.
Increase storage capacity by installing flooring boards
Most existing timber joists in homes (between the floor of the loft space and the ceiling of the rooms below) will not be able to support the significant weight required for a liveable space. The joists are designed to tie the pitched members of the roof together to prevent them spreading and also support the ceiling lining of the rooms below.
The excessive additional load required for storage may load joists beyond their design capacity. You may still require a Building Regulations Application to Building Control, even if you only want to lay flooring boards over the existing joists in the loft space. Your local Building Control body will be able to advise you on this issue.
Creating liveable space
If you want to create additional living accommodation, where you intend to use the room as a normal part of your house (this includes spare bedrooms even if used infrequently) in an existing loft space of a home it is likely to require a range of alterations.
Many of these could have an adverse impact on the building and its occupants if they are not properly thought out, planned and undertaken in accordance with the requirements of the legislation.
PropertySurveying professionals can assist and advise you on all aspects of converting existing loft space into liveable accommodation, creating more accessible storage, or if you need help with serving the required notices under the Party Walls Acts, which is a legal requirement for many property improvements.