Appendix E: Definitions

Notes: Except for the items marked * (which are from the Building Regulations), these definitions apply only to Part B.

Access room: A room through which the only escape route from an inner room passes.

Accommodation stair: A stair, additional to that or those required for escape purposes, provided for the convenience of occupants.

Alternative escape routes: Escape routes sufficiently separated by either direction and space, or by fire-resisting construction, to ensure that one is still available should the other be affected by fire.

Note:A second stair, balcony or flat roof which enables a person to reach a place free from danger from fire, is considered an alternative escape route for the purposes of a dwellinghouse.

Alternative exit: One of two or more exits, each of which is separate from the other.

Appliance ventilation duct: A duct provided to convey combustion air to a gas appliance.

Automatic release mechanism: A device which will allow a door held open by it to close automatically in the event of each or any one of the following:

A. detection of smoke by automatic apparatus suitable in nature, quality and location;

B. operation of a hand-operated switch fitted in a suitable position

C. failure of electricity supply to the device, apparatus or switch

D. operation of the fire alarm system if any.

Basement storey: A storey with a floor which at some point is more than 1200mm below the highest level of ground adjacent to the outside walls.

Boundary: The boundary of the land belonging to the building, or where the land abuts a road, railway, canal or river, the centre line of that road, railway, canal or river (See Diagram 17.)

* Building: Any permanent or temporary building but not any other kind of structure or erection. A reference to a building includes a reference to part of a building.

Building Control Body: A term used to include both Local Authority Building Control and Approved Inspectors.

Cavity barrier: A construction, other than a smoke curtain, provided to close a concealed space against penetration of smoke or flame, or provided to restrict the movement of smoke or flame within such a space.

Ceiling: A part of a building which encloses and is exposed overhead in a room, protected shaft or circulation space. (The soffit of a rooflight is included as part of the surface of the ceiling, but not the frame. An upstand below a rooflight would be considered as a wall.)

Circulation space: A space (including a protected stairway) mainly used as a means of access between a room and an exit from the building or compartment.

Class 0: A product performance classification for wall and ceiling linings. The relevant test criteria are set out in Appendix A, paragraph 13.

Compartment (fire) A building or part of a building, comprising one or more rooms, spaces or storeys, constructed to prevent the spread of fire to or from another part of the same building, or an adjoining building. (A roof space above the top storey of a compartment is included in that compartment.) (See also ‘Separated part’.)

Compartment wall or floor A fire-resisting wall/floor used in the separation of one fire compartment from another. (Constructional provisions are given in Section 5.)

Concealed space or cavity: A space enclosed by elements of a building (including a suspended ceiling) or contained within an element, but not a room, cupboard, circulation space, protected shaft or space within a flue, chute, duct, pipe or conduit.

Dead end: Area from which escape is possible in one direction only.

Direct distance: The shortest distance from any point within the floor area, measured within the external enclosures of the building, to the nearest storey exit ignoring walls, partitions and fittings, other than the enclosing walls/partitions to protected stairways.

Dwellinghouse: A unit of residential accommodation occupied (whether or not as a sole or main residence):

A. by a single person or by people living together as a family

B. by not more than six residents living together as a single household, including a household where care is provided for residents. (See also paragraphs 0.22 and 0.23.)

* Dwellinghouse does not include a flat or a building containing a flat.

Element of structure:

A. a member forming part of the structural frame of a building or any other beam or column;

B. a loadbearing wall or loadbearing part of a wall;

C. a floor;

D. a gallery (but not a loading gallery, fly gallery, stage grid, lighting bridge, or any gallery provided for similar purposes or for maintenance and repair);

E. an external wall;

F. a compartment wall (including a wall common to two or more buildings). (However, see the guidance to B3, paragraph 4.4, for exclusions from the provisions for elements of structure.)

Escape lighting That part of the emergency lighting which is provided to ensure that the escape route is illuminated at all material times.

Escape route Route forming that part of the means of escape from any point in a building to a final exit.

European Technical Approval A favourable technical assessment of the fitness for use of a construction product for an intended use, issued for the purposes of the Construction Products Directive by a body authorised by a Member State to issue European Technical Approvals for those purposes and notified by that Member State to the European Commission.

European Technical Approvals issuing body A body notified under Article 10 of the Construction Products Directive. The details of these institutions are published in the ‘C’ series of the Official Journal of the European Communities.

Evacuation lift A lift that may be used for the evacuation of people in a fire.

Exit passageway A protected passageway connecting a protected stairway to a final exit (exit passageways should be protected to the same standard as the stairway that they serve).

External wall (or side of a building) Includes a part of a roof pitched at an angle of more than 70º to the horizontal, if that part of the roof adjoins a space within the building to which persons have access (but not access only for repair or maintenance).

Final exit The termination of an escape route from a building giving direct access to a street, passageway, walkway or open space, and sited to ensure the rapid dispersal of persons from the vicinity of a building so that they are no longer in danger from fire and/or smoke.

Notes: Windows are not acceptable as final exits.

Fire door A door or shutter, provided for the passage of persons, air or objects, which together with its frame and furniture as installed in a building, is intended (when closed) to resist the passage of fire and/or gaseous products of combustion, and is capable of meeting specified performance criteria to those ends. (It may have one or more leaves, and the term includes a cover or other form of protection to an opening in a fire-resisting wall or floor, or in a structure surrounding a protected shaft.)

Fire-resisting (fire resistance) The ability of a component or construction of a building to satisfy, for a stated period of time, some or all of the appropriate criteria specified in the relevant part of BS 476.

Fire-separating element A compartment wall, compartment floor, cavity barrier and construction enclosing a protected escape route and/or a place of special fire hazard.

Fire stop A seal provided to close an imperfection of fit or design tolerance between elements or components, to restrict the passage of fire and smoke.

* Flat A separate and self-contained premises constructed or adapted for use for residential purposes and forming part of a building from some other part of which it is divided horizontally.

GalleryA raised area or platform around the sides or at the back of a room which provides extra space.

Habitable room A room used, or intended to be used, for dwellinghouse purposes (including; for the purposes of Part B, a kitchen, but not a bathroom).

Height (of a building or storey for the purposes of Part B) Height of the top storey above ground is measured as shown in Appendix C, Diagram C1.

Inner room Room from which escape is possible only by passing through another room (the access room).

Material of limited combustibility A material performance specification that includes non-combustible materials, and for which the relevant test criteria are set out in Appendix A, paragraph 9.

Means of escape Structural means whereby [in the event of fire] a safe route or routes is or are provided for persons to travel from any point in a building to a place of safety.

Non-combustible material The highest level of reaction to fire performance. The relevant test criteria are set out in Appendix A, paragraph 8.

Notional boundary A boundary presumed to exist between buildings on the same site (see Section 9, Diagram 18).

Occupancy type A purpose group identified in Appendix D.

Pipe (for the purposes of Section 7) Includes pipe fittings and accessories; and excludes a flue pipe and a pipe used for ventilating purposes (other than a ventilating pipe for an above around drainage system).

Places of special fire hazard Oil-filled transformer and switch gear rooms, boiler rooms, storage space for fuel or other highly flammable substances, and rooms housing a fixed internal combustion engine.

Protected circuit An electrical circuit protected against fire.

Protected stairway A stair discharging through a final exit to a place of safety (including any exit passageway between the foot of the stair and the final exit) that is adequately enclosed with fire-resisting construction.

Purpose group A classification of a building according to the purpose to which it is intended to be put. See Appendix D, Table D1.

Relevant boundary The boundary which the side of the building faces, (and/or coincides with) and which is parallel, or at an angle of not more than 80º, to the side of the building (see Section 9 Diagram 17). A notional boundary can be a relevant boundary.

Rooflight A dome light, lantern light, skylight, ridge light, glazed barrel vault or other element intended to admit daylight through a roof.

Room (for the purposes of B2) An enclosed space within a building that is not used solely as a circulation space. (The term includes not only conventional rooms, but also walk-in cupboards that are not fittings, and large spaces such as warehouses and auditoria. The term does not include voids such as ducts, ceiling voids and roof spaces.)

Sheltered housing Includes:

a. two or more dwellings in the same building;

b. two or more dwellings on adjacent sites

where those dwellings are, in each case, designed and constructed for the purpose of providing residential accommodation for vulnerable or elderly people who receive, or who are to receive, a support service.

Single-storey building A building consisting of a ground storey only. (A separated part which consists of a ground storey only, with a roof to which access is only provided for repair or maintenance, may be treated as a single storey building.) Basements are not included in counting the number of storeys in a building.

Site (of a building) The land occupied by the building, up to the boundaries with land in other ownership.

Smoke alarm A device containing within one housing all the components, except possibly the energy source, necessary for detecting smoke and giving an audible alarm.

Self-closing device A device which is capable of closing the door from any angle and against any latch fitted to the door.


a. any gallery if its area is more than half that of the space into which it projects; and

b. a roof, unless it is accessible only for maintenance and repair.

Storey exit A final exit, or a doorway giving direct access into a protected stairway, firefighting lobby or external escape route.

Suspended ceiling (fire-protecting) A ceiling suspended below a floor, which contributes to the fire resistance of the floor. Appendix A, Table A3, classifies different types of suspended ceiling.

Technical specification specification A standard or a European Technical Approval Guide. It is the document against which compliance can be shown in the case of a standard and against which an assessment is made to deliver the European Technical Approval.

Thermoplastic material See Appendix A, paragraph 17.

Unprotected area In relation to a side or external wall of a building means

a. window, door or other opening; and

Note: Windows that are not openable and are designed and glazed to provide the necessary level of fire resistance need not be regarded as an unprotected area.

b. any part of the external wall which has less than the relevant fire resistance set out in Section 8.

c. any part of the external wall which has combustible material more than 1mm thick attached or applied to its external face, whether for cladding or any other purpose. Combustible material in this context is any material which does not have a Class 0 rating.)

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