18.1 General

a) Automatic Sprinklers: Covered in 6.5; affects risk profile, to be determined early.

b) Minimum Protection: Buildings must meet the minimum fire protection measures in Clauses 15 to 17.

Additional Measures: If additional fire protection is provided (Clauses 18.2 and 18.3):

● Travel Distance: May be increased as per Table 11.

● Door and Stair Widths: May be reduced as per Tables 12 and 13.

● Review: Increases/reductions must be reviewed and assessed by designers.

Figure 17 Process for assessing additional fire protection measures

NOTE 1 Two worked examples are given below, for the same building risk profile, one with and one without sprinklers.

NOTE 2 The authority having jurisdiction is also likely to review and assess any changes.

EXAMPLE 1 Office building

1. Base Case (Risk Profile A2):

a) Fire Protection:

● Manual fire detection linked to electronic fire alarm.

● Travel Distance:

● Maximum: 22 m (single direction)

● Alternative: 55 m

● Exit Width: 3.6 mm/person (Table 12)

● Stair Width: 2.0 mm/person (Table 13)

2. Enhancements:

a) Automatic Fire Detection:

b) 15% variation: (Table 14)

● Travel Distance: 27.5 m (single), 68.8 m (alternative)

● Exit Width: 2.7 mm/person

● Stair Width: 1.5 mm/person

c) Ceiling Height Variation (4-5 m):

● Additional 10% variation:

● Travel Distance: 27.5 m (single), 68.8 m (alternative)

● Exit Width: 2.7 mm/person

● Stair Width: 1.5 mm/person

3. Maximum/Minimum Limits:

a) Maximum Travel Distance: (Table 15)

● Single: 26 m

● Alternative: 75 m

● Minimum Exit Width: 3.0 mm/person

● Minimum Stair Width: No less than 75% of original width

b) Final Values:

c) Travel Distance:

● Maximum: 26 m (single direction)

● Alternative: 68.8 m

● Exit Width: 3.0 mm/person

● Stair Width: 1.5 mm/person

4. With Sprinkler Protection (Risk Profile A1):

a) Fire Protection:

● Manual fire detection linked to electronic fire alarm.

● Travel Distance:

● Maximum: 26 m (single direction)

● Alternative: 65 m

● Exit Width: 3.3 mm/person

● Stair Width: 1.8 mm/person

b) Enhancements:

● 15% variation:

● Travel Distance: 30 m (single), 81.3 m (alternative)

● Exit Width: 2.5 mm/person

● Stair Width: 1.3 mm/person

EXAMPLE 2 Shop

Base Case (Risk Profile B3): (Table 7)

a) Fire Protection:

● Automatic fire detection (type L2) + electronic fire alarm

b) Travel Distance:

● Maximum: 16 m (single direction) (Table 11)

● Alternative: 40 m

● Exit Width: 6.0 mm/person (Table 12)

● Stair Width: 6.0 mm/person (Table 13)

2. Enhancements:

a) Voice Alarm: 15% variation applies (Table 14)

b) Travel Distance:

● Maximum: 20 m (single direction) (Table 15)

● Alternative: 50 m

● Exit Width: 4.5 mm/person

● Stair Width: 4.5 mm/person

c) Ceiling Height Variation: Additional 10%

d) Travel Distance:

● Maximum: 20 m (single direction)

● Alternative: 50 m

● Exit Width: 4.5 mm/person (Table 12)

● Stair Width: 4.5 mm/person (Table 13)

e) Limits:

3. Maximum Travel Distance:

● Single: 20 m

● Alternative: 60 m

● Minimum Exit Width: 5.3 mm/person

● Minimum Stair Width: 75% of original width

a) Final Values:

b) Travel Distance:

● Maximum: 20 m (single direction)

● Alternative: 50 m

● Exit Width: 5.3 mm/person

● Stair Width: 4.5 mm/person

4. With Sprinkler Protection (Risk Profile B2):

a) Fire Protection:

● Manual fire detection + electronic fire alarm

b) Travel Distance:

● Maximum: 20 m (single direction)

● Alternative: 50 m

● Exit Width: 4.1 mm/person

● Stair Width: 4.0 mm/person

c) Variations:

d) Travel Distance:

● Maximum: 24 m (single direction)

● Alternative: 62.5 m

● Exit Width: 3.3 mm/person

● Stair Width: 3.0 mm/person

e) Final Values:

f) Travel Distance:

● Maximum: 24 m (single direction)

● Alternative: 62.5 m

● Exit Width: 3.3 mm/person

● Stair Width: 3.0 mm/person

18.2 Automatic detection and informative warning systems

COMMENTARY ON 18.2

a) Early Warning:

● Automatic fire detection systems reduce time to detection, providing early warning to occupants.

b) Voice Alarms:

● Installing voice alarms enhances information about fire incidents, reducing pre-movement time for occupants unfamiliar with the building.

c) Response Variability:

● Occupants in office buildings (familiar and trained) respond more quickly to fire alarms.

● Occupants in shops (unfamiliar and focused on personal tasks) may respond more slowly and rely on staff instructions.

d) Voice Alarm Benefit:

● In buildings requiring automatic fire detection (occupancy characteristic B), incorporating a voice alarm system improves response compared to non-voice sounders.

e) Allowable Variations:

● With a clear benefit from automatic fire detection and voice alarm systems, allowable variations include:

● 15% increase in travel distance.

● 15% reduction in door, corridor, and stair widths.

● Ensure maximum acceptable variations are not exceeded.

NOTE Where detection and warning systems and/or voice alarms are required as part of the minimum package of fire protection measures recommended in Clause 15, no variation is permitted to the travel distances, door widths, corridor widths and stair widths recommended therein.

18.3 Effect of ceiling heights

COMMENTARY ON 18.3

a) Safety Advantage:

● High ceilings delay smoke accumulation, making rooms safer for escape.

b) Allowable Variations:

● Travel Distance: Can be increased.

● Door, Corridor, and Stair Width: Can be decreased.

c) Conditions:

● Variations must not exceed percentages specified in Table 14.

● High ceiling must be maintained throughout the escape route (excluding corridors and lobbies).

● Assess the risk considering the fire load's position, height, and nature.

● Ensure variations stay within maximum acceptable limits in 18.4.

d) Measurement:

● Height should be measured clear of obstructions like roof eaves and down stand beams.

Table 14 Permissible variations in travel distance, door width, corridor width and stair width with ceiling height

Room height

Maximum permissible increase in travel distance and reduction in door width, corridor width and stair width

All risk profiles except A4, B4 and C4 A)

Risk profiles A4, B4, and C4 A)

m	%	%
≤3	Not allowable	Not allowable
>3, ≤4	5	Not allowable
>4, ≤5	10	Not allowable
>5, ≤6	15	Not allowable
>6, ≤7	18	Not allowable
>7, ≤8	21	Not allowable
>8, ≤9	24	Not allowable
>9, ≤10	27	Not allowable
>10	30	Not allowable

18.4 Maximum acceptable variations

18.4.1 General

The percentage variations given in 18.2 and 18.3 may be added together and applied as a total, provided that the result is within the limits given in 18.4.2 to 18.4.4.

18.4.2 Travel distances

Travel distances should not exceed the maximum distance given in Table 15 for the appropriate risk profile.

18.4.3 Door and corridor widths

Door and corridor widths should be not less than the value given in Table 16 for the appropriate risk profile, subject to the minimum width recommendations in 16.6.1.

18.4.4 Stair width

The stair width should be not less than the absolute minimum given in 17.4.1 and the available width per person should be not less than 75% of the value given in Table 13.

Table 15 Maximum travel distances when additional fire protection measures are provided

Table 16 Door widths when additional fire protection measures are provided.

18 Additional fire protection measures