04 Fire Safety Design

Question 1

What guidance is available to designers in relation to fire safety?

Answer 1

1. Building Regulations Approved Document B (Fire Safety)
2. BS 9999:2008 - Code of practice for fire safety in the design, management and use of buildings
3. Building Bulletin 100 - Design for fire safety in schools

Question 2

What are the main requirements of Part B of the Building Regulations?

Answer 2

Covers all precautionary measures necessary to provide safety from fires, including:

1. Means of escape
2. Fire detection and warning systems
3. Fire resistance of structural elements
4. Fire separation, protection and compartmentation to prevent fire spread
5. Control of flammable materials
6. Access and facilities for firefighting

Question 3

What are the basic principles for means of escape in buildings?

Answer 3

1. Should always provide an alternative means of escape (should always be able to turn your back on a fire)
2. Protected routes (e.g. compartmentation of staircases and corridors, provision of cavity barriers)
3. Maximum travel distances (varies depending on building use)
4. Minimum widths (varies depending on occupancy levels)
5. Signage
6. Emergency/escape lighting
7. Refuge point (must be provided for each protected stairway)
8. Evacuation lift
9. Non-slip flooring
10. Ramps (conforming to BS 8300)

Question 4

What are travel distances and what are the maximum travel distances for different building uses?

Answer 4

Actual distance to be travelled by a person from any point within a floor area to the nearest storey exit.

• In residential premises such as apartment blocks, the maximum distance from a dwelling entrance door to a common staircase, or to a door to a lobby in corridor-access single-stair flats is 7.5m where there is only one direction of escape.
• When a flat is served by more than one common stair giving more than one direction of escape, the maximum distance from a dwelling entrance door to a common staircase increases to 30m.
• In shops and commercial buildings, this increases to 18m in one direction, or 45m in multiple directions.
• travel distances permitted under ADB for industrial premises, with 25m in one direction, though the 45m limit still applied where there is more than one direction of escape.

Question 5

What are the main requirements for doors on escape routes?

Answer 5

1. Should not contain a lock (although if needed, must be capable of being easily unlocked without a key/combination code - may be connected to the fire alarm to automatically unlock)
2. Should open in the direction of escape
3. Must open no less than 90°
4. Vision panels required on routes sub-dividing corridors or doors that swing both ways

Question 6

What is the purpose of a fire door?

Answer 6

To protect escape routes from smoke and fire

Question 7

What are the main provisions for fire doors in dwellings?

Answer 7

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Question 8

What are the main provisions for fire doors in buildings other than dwellings?

Answer 8

1. Must be able to achieve the appropriate performance (set out in Table B1, generally 30 minutes but varies depending on location)
2. Must be fitted with self-closing devices (may be held open but automatically released in the event of a fire)
3. Must contain the appropriate signage (e.g. ‘fire door keep shut’)
4. Intumescent strips
5. Smoke seals
6. May need a third hinge depending on type/weight
7. Any glazing must be fire resistant (e.g. Embedded Georgian wire, tempered and toughened glass etc.)
8. Must show the appropriate certification

Question 9

What is the reason for intumescent material, why do we install it?

Answer 9

To seal around the fire door, to ensure compartmentation is not breached.

Question 10

At what temperature does the intumescent material activate?

Answer 10

200-250 degrees C

Question 11

What key elements would provide an acceptable refuge?

Answer 11

1. Safe waiting areas for disabled people on protected stairways
2. Not necessarily in the stairway itself, but needs direct access onto it (e.g. a protected lobby)
3. Minimum dimensions: 900mm x 1400mm
4. Must not reduce the width of the escape route
5. Clearly identified (‘refuge - keep clear’)
6. Emergency voice communication (EVC) system should be provided

Question 12

What is the difference between active and passive fire protection systems?

Answer 12

• Passive fire protection is the primary measure integrated within the construction fabric of a building to provide fire safety and protection
• Active fire protection is fire protection which requires a command signal to operate, i.e. it is responsive

Question 13

Give some examples of active and passive fire protection systems.

Answer 13

Passive:

1. Compartmentation walls/ceilings
2. Fire doors
3. Cavity barriers
4. Intumescent paint on steel

Active:

1. Detection/alarm systems
2. Fire suppression systems (e.g. sprinkler systems, water mist systems)
3. Automatic door closers

Question 14

What are the main requirements for means of fire/heat detection in dwellings?

Answer 14

All dwellings should be provided with an alarm system to at least Grade D1/D2, Category LD3 – this means the installation of mains powered alarms with an integral back-up power supply within the escape routes of the property (i.e. hallways and landings). In addition, the Regulations also require a heat alarm to be installed in any kitchen areas where the kitchen is not separated from the circulation space or stairway by a door.

The Regulations state that optical smoke alarms are generally more suitable for installation in circulation areas (hallways and landings) adjacent to kitchens. Heat alarms are recommended for kitchens.

All alarms should be interconnected to ensure audibility throughout the property in event of an alarm being triggered.

The Regulations also reference the British Standard BS 5839-6:2019 and recommend that an alarm system is installed in-line with this Standard.

Question 15

What fire safety systems are there in a typical school building?

Answer 15

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Question 16

What are the main requirements for fire safety in higher domestic buildings?

Answer 16

Sprinkler systems

Question 17

Do buildings have to have a fire certificate?

Answer 17

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Question 18

What are the requirements for loft conversions?

Answer 18

Where a new storey is added through conversion to create a storey above 4.5m, both of the following should apply.

The full extent of the escape route should be addressed.

Fire resisting doors (minimum E 20) and partitions (minimum REI 30) should be provided,

including upgrading the existing doors where necessary.

NOTE: Where the layout is open plan, new partitions should be provided to enclose the escape

route (Diagram 2.2).

2.22 Where it is undesirable to replace existing doors because of historical or architectural merit, the

possibility of retaining, and where necessary upgrading, them should be investigated.

2.23 An alternative approach to that described in paragraph 2.21 would be to comply with all of the following.

Provide sprinkler protection to the open-plan areas.

Provide a fire resisting partition (minimum REI 30) and door (minimum E 20) to separate the ground storey from the upper storeys. The door should allow occupants of the loft room access to a first storey escape window.

Separate cooking facilities from the open-plan area with fire resisting construction (minimum REI 30).

Question 19

What are the requirements for an escape window?

Answer 19

To rooms not higher than 4.5m

Windows should have an unobstructed openable area that complies with all of the following.

• A minimum area of 0.33m2
• A minimum height of 450mm and a minimum width of 450mm (the route through the window may be at an angle rather than straight through).
• The bottom of the openable area is a maximum of 1100mm above the floor.

People escaping should be able to reach a place free from danger from fire.

Locks (with or without removable keys) and opening stays (with child-resistant release catches) may be fitted to escape windows.

Windows should be capable of remaining open without being held.

Question 20

What are fire requirements for basements?

Answer 20

1. 60mins Fire compartmentation
2. Basement storeys containing habitable rooms should have one of the following.
3. An emergency escape window or external door providing escape from the basement.
4. A protected stairway (minimum REI 30) leading from the basement to a final exit.

Question 21

Can two rooms be served by one escape window?

Answer 21

Yes.

A door between the rooms should provide access to the escape window without passing through the stair enclosure.

Both rooms should have their own access to the internal stair.

Question 22

With respect to flats, what are the requirements for means of escape to flats at ground floor level?

Answer 22

All habitable rooms - excluding kitchens - should have either:

• An opening directly onto a hall leading to a final exit.

or

• An emergency escape window or door

Question 23

What are the requirements for means of escape for upper level apartments, not exceeding 4.5m in height?

Answer 23

All habitable rooms (excluding kitchens) should have either of the following:

• An emergency escape window or external door, as described in paragraph 3.6.
• In multi-storey flats, direct access to a protected internal stairway (minimum REI 30) leading to an exit from the flat.

Question 24

What are the requirements for means of escape for single story flats above 4.5m in height from ground level?

Answer 24

Either of the following:

• Provide a protected entrance hall (minimum REI 30) serving all habitable rooms that meets the conditions shown in Diagram 3.2.
• Plan the flat to meet the conditions (diagram 3.3)

i. The travel distance from the flat entrance door to any point in any habitable room is a maximum of 9m.
ii. Cooking facilities are remote from the main entrance door and do not impede the escape route from anywhere in the flat.

• Provide an alternative exit from the flat

Question 25

When is an alternative exit required in flats?

Answer 25

Where it is not possible to get directly travel to a final exit, without traveling through another room.

Question 26

What are the requirements for means of escape for flats that do not provide direct access to the flat entrance without having to go through another room?

Answer 26

All of the following conditions should be met:

• Bedrooms should be separated from living accommodation by fire resisting construction (minimum REI 30) and fire doorsets (minimum E 20).
• The alternative exit should be in the part of the flat that contains the bedrooms.

Question 27

What are the requirements for an alternate exit?

Answer 27

1. It should be remote from the main entrance door to the flat.
2. It should lead to a final exit, via a common stair if necessary, through one of the following.

• A door to an access corridor, access lobby or common balcony.
• An internal private stair leading to an access corridor, access lobby or common balcony at
• another level.
• A door to a common stair.
• A door to an external stair.
• A door to an escape route over a flat roof.

Any access route leading to a final exit or common stair should comply with the provisions for means of escape in the common parts of a flat (see paragraph 3.25).

Question 28

What is the building regs requirement for means of escape in common areas?

Answer 28

A person escaping through the common area, if confronted by the effects of a fire in another flat, should be able to turn away from it and make a safe escape via an alternative route.

From the flat entrance door, a single escape route is acceptable in certain cases - see below.

Question 29

Explain when a single escape route is acceptable

Answer 29

• The flat is on a storey served by a single common stair and both of the following apply.
• Every flat is separated from the common stair by a protected lobby or common protected corridor (see Diagram 3.7).
• The maximum travel distance of 7.5m, for escape in one direction only, is not exceeded.
• The flat is in a dead end of a common corridor served by two (or more) common stairs and the maximum travel distance given of 7.5m, for escape in one direction only, is not exceeded.

Question 30

Is a single stair escape route acceptable for flats above 4.5m in height? Elsterne

Answer 30

Yes, the arrangemnt for common routes to flats not exceeding 4.5m in height can be modified for some low rise buildings, but all the following must comply:

• The top storey of the building is a maximum of 11m above ground level.
• No more than three storeys are above the ground storey.
• The stair does not connect to a covered car park, unless the car park is open sided (as defined in Section 11 of Approved Document B Volume 2).
• The stair does not serve offices, stores or other ancillary accommodation. If it does, they should be separated from the stair by a protected lobby or protected corridor (minimum REI 30) with a minimum 0.4m2 of permanent ventilation, or be protected from the ingress of smoke by a mechanical smoke control system.
• Either of the following is provided for the fire and rescue service.
  i) A high-level openable vent with a free area of at least 1m2 at each storey.
  ii) A single openable vent with a free area of at least 1m2 at the head of the stair, operable
  iii) remotely at the fire and rescue service access level.

Question 31

What are the general requirements for the common escape route?

Answer 31

Appropriate travel distance

An escape route should not pass through one stair enclosure to reach another. It may pass through a protected lobby (minimum REI 30) of one stair to reach another.

Common corridors should be protected corridors. The wall between each flat and the corridor should be a compartment wall (minimum REI 30 where the top storey is up to 5m above ground level, otherwise REI 60).

Divide a common corridor connecting two or more storey exits with a fire doorset fitted with a self-closing device (minimum E 30 Sa). See Diagram 3.8. Associated screens should be fire resisting. Site doors so that smoke does not affect access to more than one stair.

3. 36 A fire doorset (minimum E 30 Sa) fitted with a self-closing device (and fire resisting screen, where required) should separate the dead-end portion of a common corridor from the rest of the corridor (Diagrams 3.7a, 3.8b and 3.8c).
4. 37 Ancillary accommodation should not be located in, or entered from, a protected lobby or protected corridor forming the only common escape route on that storey.

Question 32

What is the minimum height for a common escape route?

Answer 32

Minimum clear headroom of 2m. The only projections allowed below this height are door frames.

Question 33

What are the requirements for flooring in common escape routes?

Answer 33

Escape route floor finishes should minimise their slipperiness when wet. Finishes include the treads of steps and surfaces of ramps and landings.

Question 34

What are the lighting requirements for escape routes?

Answer 34

All escape routes should have adequate artificial lighting. If the mains electricity power supply fails, escape lighting should illuminate the route (including external escape routes).

Escape stair lighting should be on a separate circuit from the electricity supply to any other part of the escape route.

Escape lighting should conform to BS 5266-1.

Question 35

What are the requirements for protected circuits?

Answer 35

To limit potential damage to cables in protected circuits, all of the following should apply.

Cables should be sufficiently robust.

Cable routes should be carefully selected and/or physically protected in areas where cables may be exposed to damage.

Methods of cable support should be class A1 rated and offer at least the same integrity as the cable. They should maintain circuit integrity and hold cables in place when exposed to fire.

3. 47 A
   a. Cables should achieve PH 30 classification when tested in accordance with BS EN 50200

protected circuit to operate equipment during a fire should achieve all of the following.

(incorporating Annex E) or an equivalent standard.

It should only pass through parts of the building in which the fire risk is negligible.

It should be separate from any circuit provided for another purpose.

3.48 Guidance on cables for large and complex buildings is given in BS 5839-1, BS 5266-1 and BS 8519.

Question 36

Was ventilation required at Elsterne?

Answer 36

Despite the provisions described, it is probable that some smoke will get into the common corridor or lobby from a fire in a flat.

There should therefore be some means of ventilating the common corridors/lobbies to control smoke and so protect the common stairs. This means of ventilation offers additional protection to that provided by the fire doors to the stair, as well as some protection to the corridors/lobbies.

Question 37

What is a Final Exit?

Answer 37

People should be able to rapidly leave the area around the building. Direct access to a street, passageway, walkway or open space should be available. The route away from the building should comply with the following.

Be well defined.

If necessary, have suitable guarding.

Question 38

How did the timber staircase comply?

Answer 38

Using a timber stair from a manufacturer who has obtained a suitable, independent third party approval from a UKAS accredited test house (e.g. the BWF/LPCB approval scheme for fire protected common stairs—www.bwfstairscheme.org.uk). The builder must provide evidence to the building control body that the proposed stair construction does not deviate outside the parameters of the third party approval