S20C2 covers smoke detection and alarm systems directly referenced in E2D4 to E2D20. The application of smoke detection to smoke control systems is addressed in S20C6.

S20C2 indicates the types of system, in terms of smoke alarm and/or smoke detection, applicable to various Classes of buildings. A smoke detection system is considered necessary in certain Class 3 and Class 9a buildings to facilitate system monitoring as required by S20C8.

Smoke alarm systems are required in:

• Class 2 buildings;
• smaller Class 3 buildings (see S20C2(b) regarding larger Class 3 buildings);
• Class 4 parts; and
• smaller Class 9a buildings (see S20C2(d)(i) regarding larger Class 9a buildings).

Smoke detection systems are required (and in some cases are the sole requirement to satisfy smoke hazard management provisions) in:

• Class 2 buildings;
• smaller Class 3 buildings;
• larger Class 3 buildings;
• Class 4 parts;
• Class 5–8 and Class 9b buildings (note that a smoke detection system complying with S20C4 and not a smoke alarm system complying with S20C3 is required in these buildings);
• smaller Class 9a building (see S20C2(d)(i) regarding larger Class 9a buildings);
• larger Class 9a buildings (note that a smoke detection system complying with S20C4 and not a smoke alarm system complying with S20C3 is required in these buildings); and
• Class 9c buildings.

Combined smoke alarm and smoke detection systems are permitted (as specified) in:

• Class 2 buildings;
• smaller Class 3 buildings (see S20C2(b) regarding larger Class 3 buildings); and
• Class 4 parts.

A smoke alarm system and a smoke detection system are only required to be installed when required by E2D4 to E2D20.