Loft conversions

Some loft conversions need planning permission. You should check with Building Control before starting work.

There is more information on the Planning Portal website

These works are considered a loft conversion and need a building application:

  • permanent fixed stair (not retractable ladder)
  • installing a floor
  • lining walls/rafters

You'll also need to make a building regulations application if you:

  • instal rooflights 
  • alter the existing roof structure, e.g. removal of purlins / struts

These are considered structural changes.

You can have a limited area of boarding on the floor in a loft space to use for access, maintenance, and light storage. However if there are any doubts about the structure supporting additional load you should get guidance from a competent person.

If you are unsure about any aspects of building work, consult your local Building Control department who will be happy to advise you.

Guidance notes for construction professionals 

This guide only applies to the conversion of lofts within single occupancy bungalows and 2 storey houses. Additional and different criteria apply to other buildings.

This guidance gives you an idea of what is required before you submit a building regulations application for works involving the conversion of the roof space of a dwelling. It is not intended to give full details of the regulations but to highlight the most important things to consider. These works can be more complex than other extensions and we recommend you get professional assistance before submitting a Building Regulation application.

Structural considerations

Most ceiling structures are not strong enough to serve as a floor.  Upgrading the structure will involve the installation of new floor joists and in some cases adding steel or timber beams to carry the floor and roof loads. Existing walls, lintels and beams may need to be checked to make sure they can carry additional loads. In some cases foundations may need to be exposed and checked.

You'll usually need a structural engineer to calculate the sizes of new structural members (beams, columns and tension structures, frames and trusses).

Fire safety

Single storey dwellings

For the conversion of the attic of a single storey dwelling (bungalow), you may only need to provide: 

  • escape windows to the new habitable rooms at first floor 
  • mains interlinked smoke detectors/alarms in the circulation spaces on the ground and first floor

Each habitable room on the first floor should be provided with an escape window. Windows must:

  • have a clear opening of at least 0.33m2 
  • measure at least 450mmx450mm
  • be between 800mm and 1100mm above the finished floor level

If a pass door is provided between the 2 rooms and both rooms open onto the new stairway, then only one escape window is needed.

2-storey dwellings

Creating a room in the roof of a 2 storey house potentially increases the risk to occupants in the event of a fire.  As a result, regulations require a protected escape route from the new rooms at second floor level to a final ground floor exit (such as the front door). 

The structure forming this enclosure must have 30 minute fire resistance and the doors must be fire doors. Existing floors separating rooms from landing areas may need to be upgraded to achieve a 30-minute fire rating.

Smoke detectors

Smoke alarms should be fitted at every floor level.  These should be mains powered with a battery back up supply and conform to BS.5446.  

Optical type detectors (rather than ionisation type) are less prone to false alarms.  They should be fitted in hallways and landings (following the manufacturers’ guidance).  They should also be linked so that a single unit activating will set off all the sounders in the dwelling.

Enhanced fire detection option

In certain circumstances, if your escape route does not meet the above standards, you may be able to compensate with an enhanced automatic fire detection and alarm system.  

This option is applicable if all these conditions are met. The conversion must:

  • be a typical loft conversion 
  • form up to 2 new rooms at second floor level
  • have a total floor area not exceeding 50 square metres and no one floor level in the property exceeding 200 square metres

In such cases Building Control may accept the provision of a Grade D LD1 standard fire alarm system as described in BS 5839 Part 6 instead of fitting replacement fire doors to rooms off an enclosed stairway.

Such a system will have smoke detectors sited in hallways and landings at all floor levels. They must also be sited in all habitable rooms and areas where a fire might start. These must communicate with the stair enclosure. 

Heat alarms should be used in place of smoke alarms in kitchens and other rooms with a use that may trigger false alarms. Any cupboards containing potential ignition sources that are off the stair should also be provided with a detector or should be fitted with a FD30 fire door.

Hard-wired or radio-linked systems are acceptable. All detectors link to central control and indicating equipment as below. Mains power should be sourced from a regularly used local lighting circuit with lithium type rechargeable batteries giving a 72 hour back up supply.

Owners and occupiers must be aware of the above information and the need for regular testing and maintenance. They should also be informed about the importance of the equipment in providing essential early warning in fire and an adequate means of escape. Contact your local office for further information on this option.

Escape routes

It is usually necessary for the stair enclosure to lead directly to a final exit to external air (for example through a ground floor hallway) without passing through a room (as in fig 1).  If this cannot be achieved then it is permissible to form 2 alternative routes to exits that are separated from each other by fire resisting construction and fire doors. (as fig2).

Achieving these requirements can be difficult and undesirable to clients with open plan ground floor layouts. Recognising this, the regulations allow an alternative arrangement incorporating a sprinkler system. Using this option, the ground floor is separated from the upper floor by a fire resisting partition and fire door at either ground or first floor level. A residential sprinkler system to BS 9251:2014 is fitted to cover the ground floor only with any kitchen being separated from the space by fire resisting construction. This allows a viable alternative emergency escape route from the new loft rooms through suitable escape windows at first floor level. 

Stairs

A retractable ladder is not a permitted means of access to a loft conversion. The 3 options that can be considered are:

  • standard staircases
  • spiral staircases
  • alternating tread (‘space saver’) staircases

The last type is only acceptable if it serves a single room (and a bathroom) and where it is not possible to create enough space for a standard or spiral stair.

The pitch (steepness) of the stairs and the dimensions of steps and balustrades must comply with the appropriate Building Regulations contained in Approved Document K.  A full 2.0metre headroom is normally required over new stairs, although a reduced dimension is sometimes acceptable under sloping ceilings if this is not achievable. Most local authorities will accept a reduced stair width of 600mm where it only gives access to 1 or 2 new bedrooms.

If it is impractical to install a standard stair in a loft conversion, a designer may alternatively follow the guidance for ‘limited access’ stairs in BS 5395-4:2011. This permits steeper pitches of up to 50o and smaller going (tread) dimensions, although it includes the requirement to provide stair gates at the top and bottom in the interests of the safety of very young children.

Sound insulation

If your property is attached to another, you have to think about sound insulation in the loft space. If the walls are a lower quality than the walls on the habitable floors, the local authority may require you upgrade them. 

If no party wall exists in the loft, a new wall must be constructed up to the underside of the roof finish. It must have appropriate fire-stopping measures. The specifications of this wall should comply with Approved Document E that deals with sound insulation.

Thermal insulation

A loft conversion creates new thermal elements. Thermal insulation needs to be upgraded to comply with Building Regulations. 

Electrical installation

Electrical installation must comply with Part P of the Building Regulations. 

Design, installation, inspection and testing should be carried out by a contractor who is a member of a competent person’s scheme for electrical wiring approved by the Secretary of State. If this is not the case then you should contact Building Control for advice on checking this part of the work.

Email: buildingcontrol@redbridge.gov.uk

The Party Wall Act 1996

The Party Wall Act means building owners must notify adjoining owners if they are carrying out works to a wall that separates dwellings. This often applies for loft conversions in semi detached and terraced properties. 

The Act is civil legislation that is not enforced by your Local Authority. Having planning permission and Building Regulations approval does not mean that you don’t have to comply with it.