Information Sheet 21



Converting the attic space of a house is often a convenient way of obtaining additional living space without the need to extend the building. However, there are many issues to be addressed before any works are carried out, including the legal requirement to comply with the Building Regulations.

This note is intended to draw attention to the importance of dealing with Part B of the Building Regulations, which sets out mandatory fire safety requirements; and Technical Guidance Document B (TGD-B), which shows how to comply with Part B of the Building Regulations.

It should be noted that in total there are thirteen Parts to the Building Regulations and that the twelve other Parts must also be fully complied with, where relevant, including:

  • Part A - Structures
  • Part D - Materials and Workmanship
  • Part E - Sound Insulation
  • Part F - Ventilation
  • Part L - Conservation of Fuel and Energy, including thermal insulation

The various Technical Guidance Documents, Parts A - M inclusive, can be viewed on the Department of the Environment, Heritage and Local Government's website: www.environ.ie or purchased from the Government's Publications Sales Office, Sun Alliance House, Molesworth St., Dublin 2 (Tel: 01-647 6000).

Before deciding to carry out any works you should get Professional advice (e.g. Architect, Engineer) and carry out an assessment of the feasibility of achieving the accommodation you require and compliance with the statutory requirements (i.e. Planning and Building Regulations).

Professional advice should include the design of the conversion, the selection of a competent contractor, the supervision of the works, the certification of payments to the contractor and certification of compliance with the Planning / Building Regulations for the completed conversion. (Having a Compliance Certificate on file will be important should decide to sell your house in the future.)

Professional advice will also help to identify and resolve any important structural issues, (e.g. determining whether or not the existing ceiling joists can support new flooring) and help ensure that the access to, and emergency exit from, the converted attic space is by means of a secure stairway (pull down steps are not acceptable). The cost of professional services should pay for itself by helping to ensure that the conversion is up to standard, both in design and construction, adds value to your property and is safe for you and your family.

When the attic space of a house is converted to living accommodation, an additional storey effectively added to the house. Additional storey height increases the difficulty of escape should a fire occur and the provisions required under the Building Regulations are therefore increased accordingly. This is particularly the case for a three-storey house, where the existing stairs and the new stairs should be enclosed in fire resisting construction.

The technical guidance to the Building Regulations makes special provisions for attic conversions in existing two-storey houses, where the conversion provides not more than two habitable rooms and where the additional accommodation is less than 50m². These special provisions relate to the means of enclosing the stairs to the new storey and the upgrading of the protection to the existing stairway.

The habitable room (or rooms) in the new storey should be provided with either a window or roof light which is suitable for escape or rescue, as described in TGD-B.

Fire Safety:

As a general guide, if your conversion does not raise the roof line above the existing ridge, is 50m² or less and is divided into no more than two rooms, the following fire safety provisions would apply:

  1. The existing stairway must be enclosed by fire resisting walls or partitions.
  2. The fire-resisting enclosure should be extended to a Final Exit, for example the front or back door, OR there must be access to two or more escape routes at ground level. (The alternative escape routes must be separated by fire-resisting construction.)
  3. Any new stairs must fully comply with Building Regulations Part K, Guidance on Stairways, including:
    • Maximum 42 degree pitch
    • Minimum 220 mm going
    • Maximum 220 mm rise
    • Minimum 1900 mm headroom
    • Minimum 800 mm wide
  4. The new accommodation should be separated from the existing stairway by extending the existing enclosure up into the roof space and separating the new rooms from the stairway in fire-resisting construction OR, if a new stairway is constructed in an existing room, it should be separated from the room and from the rest of the house by fire-resisting construction and a fire door at either the top or bottom of the new stairs.
  5. All new doors to habitable rooms are to be self-closing fire doors.
  6. Any glazing in the existing stairway enclosure is to be fixed shut and is to be fire-resisting.
  7. The new 'storey' should be separated from the rest of the house by a "full 30 minute" fire-resisting construction AND the existing first floor should be of "modified 30 minute fire resisting standard" or better.
  8. Each new habitable room must have a window or roof light suitable for escape or rescue. This means:
    • An unobstructed clear opening of at least 0.33m², with the width or height being a minimum of 450mm.
    • An unobstructed minimum opening of 850 mm high by 500 mm wide.
    • Any fastenings must to be readily openable from the inside.
    • The bottom of any window opening must be between 800 and 1100 mm above the new floor level.
    • The bottom of any rooflight opening must be a minimum of 600 mm above the new floor level.
    • From the eaves to the cill of a dormer window or rooflight the distance must be a maximum of 1700 mm.
    • The ground under any new window must be clear of any obstructions and be capable of supporting a ladder safely.
    • Guarding must be provided around any balcony accessible from the new storey.
  9. Interconnected mains powered smoke alarms, with battery backup, must be provided at all circulation areas that form part of the escape route and in all rooms such as kitchens and living rooms that present a high fire risk to give an LD2 system or better to BS 5839 Part 6:2004.

Structural Elements:

The Building Regulations impose various requirements for the fire resistance of floors in order to restrict the spread of fire between storeys and to protect against the premature collapse of floors during a fire. A three-storey house has higher fire resistance requirements for floors than would a two-storey house. As noted above an attic conversion in a two-storey house effectively adds an additional storey and this has implications for the both the existing first floor and for the new second floor construction.

Generally the floor to the new storey will be required to meet the fire resistance requirements for a new three-storey house. Where the new accommodation does not extend into the eaves of the roof, the fire resisting floor construction must be carried through to the external walls.

Where the attic conversion consists of no more than two rooms and is 50m2, or less, the existing first floor will normally provide the necessary fire resistance, subject to inspection and assessment.

Where a house is semi-detached or forms part of a terrace, the party wall, or walls, between adjoining houses must continue up to the roof level and the junction between the walls and roof adequately fire stopped. There must be no gaps or imperfections in the party wall construction, which would facilitate the spread of fire between houses.

Any new structural members, for example floor beams, must be provided with the required level of fire resistance.

Electrical Installations:

All electrical work must be carried out by a qualified Electrician as improperly designed or installed fittings and inadequate wiring can constitute a very serious fire hazard. Particular care should be taken with the design and installation of recessed lighting systems.

Protected Structures:

In the case of older houses, particularly those that are Protected Structures, the strict application of the guidance set out in TGD-B will not always be appropriate and alternative approaches to meeting the requirements of TGDB will need to be considered.

If your house is a Protected Structure (or a proposed Protected Structure), you may require either a Declaration or Planning Permission for an attic / conversion. Your professional adviser will be able to guide you through this process.

This note is not intended as a comprehensive guide to Fire Safety requirements in attic conversions or as an alternative to, or interpretation of the Building Regulations or TGD-B.

©Holly Park Studio Ltd.