Planning loft conversion? Know the rules!

A loft conversion for your house is considered to be permitted development, not requiring an application for planning permission, provided certain limits and conditions are met.

1. Loft conversions are NOT permitted development for houses on designated land (designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites).

2. To be permitted development any additional roof space created must not exceed these volume allowances:

• 40 cubic metres for terraced houses
• 50 cubic metres for detached and semi-detached houses

Bear in mind that any previous roof space additions must be included within this volume
allowance. Although you may not have created additional space a previous owner may have
done so.

3. An extension beyond the plane of the existing roof slope of the principal elevation that fronts a highway is NOT permitted development.

4. Materials to be similar in appearance to the existing house.

5. No part of the extension to be higher than the highest part of the existing roof.

6. Verandas, balconies or raised platforms are NOT permitted development.

7. Any side-facing windows must be obscureglazed and non-opening unless the parts which can be opened are more than 1.7 metres above the floor of the room in which it is installed.

8. Roof extensions, apart from hip to gable ones, to be set back, as far as is practicable, at least 20cms from the eaves.

9. Work on a loft or a roof may affect bats. You need to consider protected species when planning work of this type. A survey may be needed, and if bats are using the building, a licence may be required.

The permitted development allowances described here apply to houses, not flats, maisonettes or other buildings. You should check with your Local Planning Authority whether permitted development rights apply – they may have been removed. Other consents may be required if your house is listed or in a designated area.

BUILDING REGULATIONS

Building regulations approval is required to convert a loft or attic into a liveable space. This section provides guidance for making alterations to the loft space of an existing house which is no more than two storeys high. Requirements for alterations to an apartment or other dwellings like maisonettes, or houses over three storeys, will be similar but may be more extensive and possibly extend to other parts of the building.

The regulations will be applied to ensure, for example:

• the structural strength of the new floor is sufficient
• the stability of the structure (including the existing roof) is not endangered
• safe escape from fire
• safely designed stairs to the new floor
• reasonable sound insulation between the conversion and the rooms below

If you plan to make the loft space more accessible or more habitable by, for example, installing a stair to it and improving it by boarding it out and lining the walls / rafters etc, more extensive work is likely to be required and the Building Regulations are likely to apply.

It is recommended that you contact Building Control to discuss your proposal and for further advice and you must also find out whether work you intend to carry out falls within The Party Wall etc. Act 1996.

CREATING A LIVEABLE SPACE

If you decide to create a liveable space (a 'livable space' is where you intend to use the room as a normal part of your house, this includes spare bedrooms which may be 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.

With regard to the structural stability of the existing walls when undertaking a conversion of a loft space, consideration will need to be given as to how the new loads will be supported. For example, if new floor joists are provided and they are to be supported by an existing wall, the wall will need to continue all the way down through the house to a foundation or alternatively the wall will need to be provided with an adequate intermediate support.

Some houses have through lounges on the ground floor where the existing load-bearing wall that did take a load down to the foundation has been removed, or it may have originally been built as a through lounge, with a steel/timber beam installed over the opening. This beam should be checked that it is strong enough to carry any new loads from the loft conversion are added.

Generally the additional load (weight) from construction and use of the new loft room(s) does not mean a significant increase on the load being transferred to the foundations.

However, in some cases, the increase in load could be significant and the adequacy of the existing foundations to carry this extra load will need to be checked. It may be necessary for the capability of the foundations to be increased by underpinning them. A structural engineer or your Building Control Body will be able to advise you.

FIRE SAFETY

When converting an existing roof space into a room or rooms the provisions for escape need to be considered throughout the full extent of the escape route. This often means that additional fire protection will be necessary in the existing parts of the house.

For example, a typical loft conversion to a two-storey house will result in the need to provide new fire-resisting doors and sometimes partitions to protect the stairway. This is because it is too dangerous to escape via windows from floors above first floor level.

Mains powered, interlinked smoke alarms will also need to be provided within the stairway at each level.

It may also be necessary to upgrade the fire protection to some parts of the structure of the house such as the floors.

Find out more at www.planningportal.gov.uk