16 Horizontal means of escape

COMMENTARY ON CLAUSE 16

a) Means of Escape:

● Ensures safe evacuation from any point in a storey to the nearest storey exit, applicable to buildings excluding atria and shopping complexes.

b) Factors Influencing Safety:

● Fire Ignition to Evacuation Start: Time between fire start and evacuation initiation affects safety.

● Travel Time:

● Few People: Distance to a place of relative safety is crucial.

● Many People: Queuing at exits significantly impacts travel time.

c) Accessibility for Disabled People:

● Specific recommendations for horizontal means of escape are detailed in 16.7.

16.1 General

a) Escape Routes:

● Should allow a person to turn away from fire and find a safe alternative exit.

b) Route Clearance:

● Must be free of serious obstacles (e.g., raised thresholds, steps, difficult doors) to avoid undue delay, especially for disabled people.

c) Specific Requirements:

● Atria: Follow guidelines in Annex B.

● Shopping Complexes: Follow guidelines in Annex E.

16.2 Number of occupants

a) Occupancy Estimation:

● Estimate maximum occupancy considering a proportion of people with disabilities.

b) Occupant Capacity:

● Design Capacity: The maximum number of people the building is designed to hold.

● Area-Based Calculation: Divide the usable area (excluding fixed parts like stair enclosures and lifts) by the floor space factor (m² per person) from Table 9.

c) Capacity Limits:

● If based on staircases or doors, inform occupants of the restriction to control and not exceed the occupancy limit.

Table 9 Examples of typical floor space factors

Use type	Density	Floor space factor A)	Example
Offices	High	4	Call centre
	Normal	6	Typical open plan office
	Low	10	Cellular office
Shops	Normal	2	Clothing store
	Medium	4	Supermarket
	Low	7	Furniture showroom
Standing areas	Very high	0.3	People queuing
	High	0.5	Bar
	Normal	1	Theatre or cinema foyer
	Low	2	Museum of gallery
Seating area B)	Normal	0.4	Theatre or cinema auditorium

A) The factors given in Table 9 are only typical and higher or lower factors might be more appropriate depending on the circumstances of the intended use and nature of the occupants.

B) Where the number of seats is known, the floor space factor is based on that number.

16.3 Layout and number of escapes routes and exits

16.3.1 Minimum number of escape routes

a) Escape Routes:

· Provide at least two alternative escape routes from every storey or floor level to avoid being rendered impassable by fire, smoke, or fumes.

· In some cases, a single direction of escape may be acceptable (see 16.3.3).

b) Minimum Requirements:

· Number of escapes routes and exits should meet or exceed the minimum recommended in Table 10 based on the intended number of occupants.

NOTE 1 The numbers given in Table 10 are the absolute minimum; the actual number of escape routes and exits that will be needed depends on the risk profile (see Clause 6), the number of occupants in the room, tier or storey in question, and the limits on travel distance to the nearest storey exit (see 16.4), and is likely to be higher than the numbers in the table.

NOTE 2 It is only the distance to the nearest exit that is so limited. Any other exits may be further away than the defined distances.

Table 10 Minimum number of escape routes and exits from a room, tier or storey.

Maximum number of persons

Minimum number of escape

60

600

More than 600

1

2

3

a) Adjoining Compartment as Escape Route:

Conditions:

● Building must be one occupancy type.

● Compartment separated by fire-resisting walls and self-closing fire doors.

● Compartment must accommodate its own occupants plus those escaping.

● Must have exits with sufficient capacity for 50% of the total occupancy (both original and escaping occupants).

b) Escape Route Through Ancillary Accommodation:

● Allowed if not the only route from the area and clearly defined with guardrails.

c) Multi-Storey Buildings:

● Each storey should have access to more than one stair, especially from dead-end conditions.

d) Mixed-Use Buildings:

● Provide separate means of escape for each occupancy category.

● If not possible, assess the impact on safe evacuation and implement appropriate measures for categories B and C. (see 6.2, Table 2

16.3.2 Alternative escape routes

a) Separation:

● Should be separated by an angle of 45° or more at the point of divergence.

● If less than 45° apart, must be within the travel distance limit for escape in one direction or separated by fire-resisting construction. [see Figure 7d)]

NOTE Fire-resisting construction may incorporate self-closing fire doors.

Figure 7 Escape routes 45° or more apart (1 of 2)

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Figure 7 Escape routes 45° or more apart (2 of 2)

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16.3.3 Single escape routes and exits

Permissible only if:

● Occupant capacity is 60 or fewer people.

● Travel distance limit for travel in one direction is not exceeded (see 16.4).

NOTE In many cases there is no alternative at the beginning of the route. For example, there might be only one exit from a room to a corridor, from which point escape is possible in two directions. This is acceptable provided that the overall distance to the nearest storey exit is within the limits for routes where there is an alternative, and the “one direction only” section of the route does not exceed the limit for travel where there is no alternative.

16.3.4 Inner rooms and access rooms

● Occupancy Limits: Maximum 60 occupants (30 if assistance is needed).

● Room Type: Cannot be a bedroom.

● Direct Access: Must be entered directly from the access room.

● Escape Route: Should not pass through more than one access room.

● Travel Distance: Must not exceed allowable one-way travel distance.

● Fire Hazard: Access room must not be a special fire hazard and should be controlled by the same occupier.

● Protection Measures:

● Enclosures of the inner room should stop at least 500 mm below the ceiling, or

● Provide a vision panel of at least 0.1 m², or

● Install an automatic smoke detector in the access room with an audible or visible alarm in the inner room per BS 5839-1:2013 and BS EN 54-23 standard.

Figure 8 Inner room and access room

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16.3.5 Planning of exits in a central core

a) Distance:

Storey exits should be remote from each other.

b) Separation:

Exits should not be approached from the same lift lobby, common lobby, or undivided corridor.

c) Linkage:

Exits should not be linked by lift lobbies, common lobbies, or undivided corridors. (see Figure 9).

16.3.6 Access to storey exits

a) No Passage:

Avoid requiring passage through one stairway to reach another.

b) Protected Lobby:

Passing through one stairway's protected lobby to reach another stairway is acceptable.

16.3.7 Separation of circulation routes from stairways

Automatic Release: If doors are not fitted with an automatic release mechanism per BS 7273-4, the stairway and exit passageway should not be used as part of the primary circulation route at the same level.

NOTE This is because self-closing fire doors are more likely to be rendered ineffective as a result of their constant use, or because some occupants might regard them as an impediment; for example, doors might be wedged open or have their closer removed

Figure 9 Exits in a central core

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b) Example 2

A corridor connecting both stairs should be divided on both sides of the central core by doors arranged as indicated

in a) or b).

Key

1. External wall

2. Lift lobby

3. Stairs need lobby approach in buildings over 18m in height

4. Doors to accommodation (not shown) may be placed anywhere in this wall

5. Doors to accommodation (not shown) may be placed anywhere in this wall except between

16.3.8 Storeys divided into different uses

a) Number of Routes: At least two escape routes required.

b) Direct Route: One escape route must lead directly to a storey exit without passing through other parts of the storey, kitchen, or special fire hazard areas.

16.3.9 Storeys divided into different occupancies

a) Separation: Escape routes from each occupancy should not pass through other occupancies.

b) Common Areas: If using a common corridor or space, it must be a protected corridor or have a suitable automatic fire detection and fire alarm system installed throughout the storey.

16.3.10 Height of escape routes

All escape routes should have a clear headroom of not less than 2 m except in doorways.

NOTE 1 The headroom is taken to be the clear height from the floor to the underside of the structure above, e.g. a ceiling, a beam, etc.

NOTE 2 For width of escape routes, see 16.6.

16.3.11 Corridors

NOTE For width of corridors, see 16.6.

16.3.11.1 Protected corridors

Where used as part of the means of escape, the following types of corridors should be constructed as protected corridors:

a) every corridor serving a bedroom;

b) every dead-end corridor exceeding 2 m in length (but see 16.3.11.4 for recesses off corridors);

c) any corridor common to two or more different occupancies (but see also 16.3.9).

16.3.11.2 Enclosure of corridors that are not protected corridors

a) Partitions:

● Must be smoke-retarding, regardless of fire resistance rating.

● Should extend to the soffit of the structural floor above or to a suspended ceiling.

b) Doors:

● Openings into rooms should have close-fitting doors, which do not need to be fire-resisting.

16.3.11.3 Subdivision of corridors

a) Long Corridors (Over 12 m):

● Subdivide with self-closing fire doors and screens approximately mid-way between storey exits.

● Doors to rooms should also be self-closing to prevent smoke bypass.

b) Dead-End Corridors (Over 4.5 m):

● Separate from other parts of the corridor by self-closing fire doors and screens if:

● They provide two directions of escape, or

● They continue past one storey exit to another.

16.3.11.4 Recesses off corridors

Recesses less than 2 m off corridors as shown in Figure 11, and extensions of corridors beyond protected stairways as shown in Figure 12, need not meet the recommendations of 16.3.11.1 and 16.3.11.3 in respect of dead-end situations unless:

a) the corridor otherwise should be a protected corridor; or

b) the accommodation served otherwise should be separated from other parts of the building by fire-resisting construction.

Figure 10 Dead-end corridors and corridors connecting alternative exits (1 of 2)

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Figure 10 Dead-end corridors and corridors connecting alternative exits (2 of 2)

NOTE Recommendations for fire resistance of fire doors (FD) and protected corridors are given in 30.2.

Figure 11 Recesses off corridor

Figure 12 Extension of corridor beyond a protected stairway

16.3.12 External escape routes

a) Building Use:

Not for buildings with occupants needing assistance or public use areas.

b) Same Building:

The flat roof must be part of the same building being evacuated.

c) Ventilation Openings:

None within 3 m of the escape route.

d) Fire Resistance of Walls:

Walls, including doors and windows, within 3 m must have 30 min fire resistance (E 30) and no unprotected area below 1.1 m.

e) Fire Resistance of Roof Hatch/Light:

Roof hatches or lights within 3 m must have 30 min fire resistance (E 30) from the underside.

f) Route Definition and Guarding:

The route must be clearly defined and guarded by walls or barriers per BS 6180.

g) Path to Exit:

The route must lead to a storey exit or external escape route.

h) External Staircase (if applicable):

Must comply with section 17.7.

16.3.13 Progressive horizontal evacuation

a) Multiple Escape Routes: Each compartment must have two escape routes:

● Into separate adjoining compartments, or

● One exit into an adjoining compartment with an alternative escape via a storey exit.

b) Capacity and Space:

● The adjoining compartment must have standing room for occupants from both compartments (at 0.3 m² per person), or

● The escape route width from the adjoining compartment must accommodate the total occupancy of both compartments.

c) Ventilation Safety:

Ventilating systems serving both compartments must have fire/smoke dampers activated by smoke detection.

d) Smoke Protection for Doors:

Doors must have cold smoke seals and should automatically close upon smoke detection.

NOTE Progressive horizontal evacuation is a suitable means of evacuating disabled people in all occupancies (see 16.7).

Figure 13 Progressive horizontal evacuation

16.4 Travel distance

a) Maximum Travel Distance:

Should generally not exceed values in Table 11, based on the appropriate risk profile.

a) Adjustments with Fire Protection:

Travel distances may be increased with additional fire protection measures, subject to limitations in Clause 18.

b) Key Considerations:

● Higher Risk:

Shorter distances required for higher fire growth rates or unfamiliar occupants.

● Extended Distances:

Allowed when additional fire protection is in place.

● Indirect Routes:

People may not initially take the direct route to a storey exit.

● Varied Movement Speed:

Depends on occupancy characteristics.

● Variable Pre-movement Time:

Influenced by room size, occupancy characteristics, and management provision.

c) Mixed-Use Buildings:

Travel distance limits apply separately to each risk profile in the building.

d) Lower Limit Enforcement:

In mixed-use areas, if occupants with a lower travel distance limit pass through a higher limit area, the lower limit applies throughout their escape route.

NOTE 1 The travel distances recommended in this subclause are based on the time available to travel safely to an exit (see Clause 11).

NOTE 2 These distances have been determined according to the risk profile (see Clause 6), taking into account the following issues.

NOTE 3 In mixed-use buildings, or in buildings with ancillary accommodation (e.g. plant rooms), the values in Table 11 apply separately to each risk profile.

If, however, occupants subject to a lower limit rely on a route through an area where the main use is assessed with a risk profile resulting in a greater limit, then the lower limit still applies to these occupants for the whole of their escape route. (See also 6.4.)

Table 11 Maximum travel distance when minimum fire protection measures are provided A)

Risk profile	Travel distance, in metres (m)
	Two-way travel B)		One-way travel
	Direct	Actual	Direct	Actual
A1	44	65	17	26
A2	37	55	15	22
A3	30	45	12	18
A4 C)	Not applicable C)	Not applicable C)	Not applicable C)	Not applicable C)
B1	40	60	16	24
B2	33	50	13	20
B3	27	40	11	16
B4 C)	Not applicable C)	Not applicable C)	Not applicable C)	Not applicable C)
C1 C2 C3 C) C4 C)	18 12 9 Not applicable C)	27 18 14 Not applicable C)	9 6 5 Not applicable C)	13 9 7 Not applicable C)

16.5 Cellular plan floors

COMMENTARY ON 16.5

a) Travel Distance Measurement: Measure to the nearest storey exit, not to individual room exits.

b) Smoke-Resisting Partitions: Partitions should resist smoke, even if not fire-resistant, to protect unaware occupants.

c) Final Exit Width: Should accommodate the total expected number of occupants using that exit, as per guidelines in section 16.6.

16.6 Width of doors, corridors and escape routes

16.6.1 Doors

NOTE 1 For doors in corridors, see 16.6.2.

Minimum Width per Person: Should meet or exceed the values specified in Table 12 for the appropriate risk profile.

Total Door Width: Must be:

a) At least the sum of the exit widths specified in Table 12.

b) At least 850 mm where unassisted wheelchair access is required (see Annex G).

c) At least 800 mm regardless of risk profile (see Figure 14).

NOTE 2 An increased door width might be necessary on some access routes.

Table 12 Exit widths when minimum fire protection measures are provided

Risk profile	Minimum exit width per person
A1	3.3
A2	3.6
A3	4.6
A4 A)	Not applicable A)
B1	3.6
B2	4.1
B3	6.0
B4 A)	Not applicable A)
C1	3.6
C2	4.1
C3A)	6.0
C4 A)	Not applicable A)
● See Table 4.

Figure 14 measurement of door width

a) Minimum Door Width Calculation:

● For doors less than 1050 mm wide, use the formula: n=500mn = \frac {500} {m}n=m500 where:

n = number of persons accommodated,

mmm = minimum door width per person from Table 12.

b) Adjustments for Additional Fire Protection:

● Door width may be reduced if additional fire protection measures are provided (see Clause 18).

c) Mixed-Use Buildings:

● Apply the Table 12 values separately for each risk profile.

● For common routes used by different types at different times, use applicable values for each type.

● If different use types use the route simultaneously, apply the most stringent value.

d) Redundant Exits:

● Assume one exit might be unusable due to fire; remaining exits must accommodate all occupants.

● When calculating total exit capacity, discount the largest exit width.

e) Critical Feature in Crowded Rooms:

● Focus on door capacity rather than travel distances due to queuing behavior at exits.

f) Double Doors:

● One leaf should be at least 800 mm wide.

NOTE 3 This could have implications for the width of stairs, which need to be at least as wide as any storey exit leading onto them (see 17.4.1).

NOTE 4 The total number of persons that two or more available exits can accommodate is found by adding the maximum number of persons for each exit width. For example, three exits each 850 mm wide, in a building with a B2 risk profile, will accommodate 242 persons. This is calculated by:

● 500 (exit less than 1 050 mm, from equation (1) divided by 4.1 (from Table 12)

= 121;

● discount one exit;

● 2 × 121 = 242 persons [not the 579 persons who could be accommodated through a single exit 2 550 mm (i.e. 3 × 850 mm) wide].

16.6.1 Corridors and escape routes

The width of a corridor or escape route should be not less than the greater of:

a) the exit width based on the calculation in 16.6.1; or

b) 1 200 mm (see Note).

NOTE Where the corridor is not accessible to wheelchair users, the width in b) may be reduced to 1 000 mm.

a) Door Width in Corridors:

● Must be at least the corridor width minus 150 mm.

b) Gangways and Stairways in Storage Areas:

● In buildings without public access and with fixed obstructions, the minimum width should be 530 mm.

16.7 Methods of horizontal escape for disabled people

a) Phased/Zoned Evacuation Systems:

● Beneficial for managing the evacuation of disabled individuals, reducing the need for assistance in moving downstairs.

b) Phased Evacuation:

● Disabled individuals can evacuate the building or compartment in the first stage using an evacuation lift.

c) Zoned Evacuation:

● Allows horizontal movement into another fire compartment:

● Can use an evacuation lift with a back-up power supply.

● Alternatively, they can wait for assistance from building management to reach ultimate safety.

NOTE Recommendations for evacuation using lifts are given in 45.9.