Part G3 Atrium construction

This Part does not apply to an atrium which—

1. connects only 2 storeys; or
2. connects only 3 storeys if—
   1. each storey is provided with a sprinkler system (other than a FPAA101D or FPAA101H system) complying with Specification 17 throughout; and
   2. one of those storeys is situated at a level at which there is direct egress to a road or open space.

An atrium well must have a width throughout the well that is able to contain a cylinder having a horizontal diameter of not less than 6 m.

An atrium must be separated from the remainder of the building at each storey by bounding walls set back not more than 3.5 m from the perimeter of the atrium well except in the case of the walls at not more than 3 consecutive storeys if—

1. one of those storeys is at a level at which direct egress to a road or open space is provided; and
2. the sum of the floor areas of those storeys that are contained within the atrium is not more than the maximum area that is permitted in Table C3D3.

Bounding walls must—

1. have an FRL of not less than 60/60/60, and—
   1. extend from the floor of the storey to the underside of the floor next above or to the underside of the roof; and
   2. have any door openings protected with self-closing or automatic –/60/30 fire doors; or
2. be constructed of fixed toughened safety glass, or wired safety glass in non-combustible frames, with—
   1. any door openings fitted with a self-closing smoke door complying with Specification 12; and
   2. the walls and doors protected with wall-wetting systems in accordance with Specification 31; and
   3. a fire barrier with an FRL of not less than –/60/30 installed in any ceiling spaces above the wall.

If a bounding wall separating an atrium from the remainder of the building is set back from the perimeter of the atrium well, a barrier that is imperforate, non-combustible, and not less than 1 m high, must be provided.

In an atrium—

1. the roof must have the FRL prescribed in Table S5C11g; or
2. the roof structure and membrane must be protected by a sprinkler system (other than a FPAA101D or FPAA101H system) complying with Specification 17.

All areas within an atrium must have access to at least 2 exits.

Sprinkler systems, smoke control systems, fire detection and alarm systems, and emergency warning and intercom systems must be installed in compliance with Specification 31.