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8th October 2013

Alan Brinson

BS 9991 in Use

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I will cover:

• Scope

• Reasons to use BS 9991

• Applications

Scope

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Scope

• Intent of BS 9991 is to complement BS 9999

• BS 9991 and BS 9999 offer alternative approaches to

the guidance in Approved Document B

• CLG was represented on the panel for BS 9991, as

were many other stakeholders

• Hotels, HMOs, residential care/nursing homes covered

by BS 9999; hospitals by HTM 05-02

Scope

• Dwellings (single family, dwelling houses, self-

contained flats or maisonettes)

• Residential accommodation blocks (e.g. for students or

hospital staff), with individual bedrooms and the

provision of shared kitchen/sanitary facilities

constructed within a fire compartment, accommodating

not more than six persons

• Sheltered and extra care housing

• No guidance on buildings under construction

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Digression – Risk Profiles

• BS 9999 established occupancy characteristics A, B,

Ci, Cii, Ciii, D, E and fire growth rates 1,2,3,4

• BS 9991 concerns occupancy characteristics Ci and Cii

and fire growth rate 2

• BS 9999 offers reductions in some fire safety measures

if others are introduced or increased

• BS 9991 does this too but also offers layout flexibility

Reasons to use BS 9991

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Variation of Guidance

Variations to travel distances through risk reduction by an:

• Active fire-fighting system (sprinklers or water mist)

• Enhanced smoke management system

• Additional level of automatic fire detection

Limited variations in fire-fighting measures and design of

building structure if sprinkler system is provided

Variation of Guidance

Houses

• Increase vehicle access distance to 90m with sprinklers

• Three-storey house:

� Separate top storey and provide alternative escape route; or

� Protected stairway to final exit; or

� If open-plan at ground level fit a sprinkler system throughout

with fire-resisting partition and door to separate ground floor

• House with more than three storeys as above but also:

� Alternative escape route from storeys above 7.5m; or

� Protected stairway plus sprinklers throughout

AD B

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Variation of Guidance

Small buildings (<11m, single stair)

• Stair may connect to covered car park at ground level

or above if ventilation 2.5% of floor area or

mechanical ventilation + ventilated lobby

• Stair may serve ancillary accommodation if separated

by protected, ventilated lobby or corridor

• If lobby has automatic opening vent, travel distance

from flat to staircase may increase from 4.5m to 7.5m

Variation of Guidance

Stairs in Mixed Use Developments

• If 4 storeys or less: separate stairs from each

occupancy by protected lobbies at each level

• >4 storeys and dwellings not ancillary: stairs should

not communicate with other occupancies

• >4 storeys and dwellings ancillary: stairs may

communication with other occupancies AND:

� security measures must not prevent escape

� Stair separated from lower floors by protected lobbies

� If rest of building has fire detection so must dwelling

� Alternative escape route from dwelling

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Variation of Guidance

Sprinklers

Variation of Guidance

Sprinklers• A three-storey house may have an open plan ground

floor with a protected stairway to upper floors

• A four-storey house need not have a second staircase

• Maximum vehicle access distance may be increased to

90m in houses and 75m in flats

• With detection in all rooms a flat may have inner rooms

• With sprinklers in the corridors as well as flats:

� Maximum travel distances may be doubled to 15m and 30m

� Minimum boundary distances may be halved

� Max. distance to a fire-fighting shaft from 45m to 60m

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Variation of Guidance

Smoke control

• Small, single-stair buildings may have travel distance in

lobby increased from 4.5m to 7.5m if AOV >1.5m2

• If all dwellings have alternative means of escape travel

distance may be increased from 7.5m to 30m

• Central doors not required in multi-stair buildings if

travel distance is less than 15m

• Powered SHEVs permitted as an alternative to natural

ventilation in basements, if sprinklers are fitted� 10 air changes/hour

� Cope with 300ºC for 60 minutes, etc

Common variations not in BS 9991

• Single staircase direct to basement car park

• Sprinkler substitution for smoke exhaust system in

common corridors

• Water mist equivalence to sprinklers. Panel members

would prefer to wait until field experience is fed into

DD 8458-1 and it has become a full BS

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Feedback from F&RS

Feedback from F&RS

• Some F&RS suggest using BS 9991 as a means to

achieve compliance with B5: Access and facilities

for the fire service

• London Fire Brigade reports that the open-plan flat

layout variations are referenced every week but

that the flats are often outside the limits:

� Too large, sometimes due to open kitchen

� Duplex, not single storey

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Feedback from F&RS

• London Fire Brigade reports that water mist

projects are not referencing BS 9991, perhaps

because it does not fully recognise mist

• Mechanical smoke ventilation applications

reference BS 9991 for extended corridors but still

need to provide evidence that it is acceptable,

using guidance in Annex E

� BS 9991 is the first reference for smoke ventilation to

justify extended corridors

Applications

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Housing Development in Westminster

Housing Development in Westminster

• Two levels of basements including car stacker

• 11 levels of flats – 129 in total – all single storey

• Designed following BS 9991

• LD3 fire alarm throughout to grade D standard

• Top floor >30m so sprinkler system in each flat

• Mechanical smoke ventilation� Not required – claimed better than natural ventilation

� Two shafts: one supply and one extract

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Housing Development in Westminster

Studio Flats

• Travel distance within studio limited to 9m

• Cooker sited away from entrance and line of

escape

Housing Development in Westminster

Studio Flats

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Housing Development in Westminster

Open Plan Flats

• Sprinklers and LD1 detection

• Size limited to 16m x 12m

• Ceiling height at least 2.25m

• Cookers not adjacent to entrance

Housing Development in Westminster

Open Plan Flats

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Housing Development in Westminster

Penthouse Flats

• Travel distance within protected hallway 14m but

acceptable with sprinklers and LD1 detection

Housing Development in Westminster

• Basement

� L5 detection

� Sprinklers and impulse fan ventilation

� 60 minutes fire resistance in sprinklered basement less

than 10m in depth (<10m accessible)

• Fire doors, fire stopping and external wall

construction per BS 9991/AD B

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Example of Extended Corridor

With sprinklers

>7.5m

Thank you!