1.3.8.1

Provision of protected lobbies and corridors - In addition to stairways serving basements (see 1.3.7), there are other situations where an escape stairway requires the added protection of a protected lobby or corridor. These are:

(a) where the stairway is the only stairway serving a building (or part of a building) which has three or more storeys (see Appendix C, Diagram 36), except in the case in a small guesthouse (see 1.3.8.2);

(a) where the stairway serves any storey at a height greater than 20 m (see Appendix C, Diagram 38);

(b) where the building is designed for phased evacuation (see 1.3.5.4);

(c) between a protected stairway and a place of special fire risk (see 1.0.9);

(d) in a sprinklered building in which the stairway width has not been based on discounting one stairway (see 1.3.5.2); or

(e) in a building serving flats and maisonettes and other non-residential occupancy (see 1.3.2.3).

in the above mentioned situations, access to the protected stairway should be by way of protected lobbies or protected corridors at all storey levels, except at the top-most level.

1.3.8.2

Small guesthouses (Purpose Group 2(b)) - An exception to the requirement for a protected lobby or corridor to the stairway in a building served by a single escape stairway may be made in the case of a guesthouse (Purpose Group 2(b)), where the following conditions are met:

(i) the house does not contain a basement and there are not more than three storeys (see Diagram 36);

(ii) there are not more than four bedrooms on any upper storey;

(iii) the stairway is a protected stairway (see 1.3.6.2);

(iv) a fire detection and alarm system is provided in accordance with the requirements of par. 1.4.14; and

(v) all habitable rooms are provided with windows which can be used for escape or rescue (see 1.5.6).

1.3.8.3

Existing buildings - In the case of some existing buildings, the provision of protected lobbies or corridors to an existing escape stairway may not be practicable. In these situations, it would be appropriate to consider alternative solutions and the

provision of compensating features (see 1.0.11.2 and 1.0.11.3). The nature and extent of the additional measures required will depend on the circumstances of each particular case.

Where protected lobbies or corridors can not be provided, it will be necessary to consider the following items in the context of the need to ensure a satisfactory level of protection to the means of escape:

- the nature and extent of the occupancies and accommodation adjoining the protected stairway;

- the fire performance of the stairway enclosure;

- the performance of fire door assemblies as installed in the building (see Appendix B);

- smoke control measures to protect the stairway enclosure; and

- life safety protection to be provided by the fire detection and alarm system (see 1.4.14).

1.3.8.4

Requirements for protected lobbies and corridors - Every protected lobby or corridor which is required to be provided should comply with the following:-

(i) be constructed with walls having fire resistance as required in Section B3 for the protecting structure of the stairway, as per Table A1 Item 11 and any door to the lobby should be a self- closing fire door having a fire resistance not less than half that required for the wall, but not less than 30 minutes;

(ii) be constructed so that the clearance between the edges of the doors when fully open is not less than 500 mm, and the distance between the doors in the closed position is not less than 1 m, or when the distance between any two doors in the closed position is less than 1 m, the planes of such doors are at an angle to one another of not less than 90 degrees; and

(iii) in the case of a protected lobby or corridor at basement level, be ventilated by means of permanent openings to the open air having an area not less than 0.05 m2, or where the protected lobby or corridor provides access at any storey level to an enclosed car park or area of special fire risk, be ventilated by means of permanent openings to the open air having an area not less than 0.4 m2. Where the lobby or corridor is not adjacent to an external wall of the building, any connecting ventilation duct- work should be protected by fire-resisting construction.

1.3.8 Protected Lobbies and Corridors to Escape Stairways

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