Design of Fire safety in Multi Occupancy Residential
Accommodation
Myth vs Reality
Myth. Fire is bright
Reality. It isn’t.
Flames are bright
Outside fires have bright
flames because of the
availability of oxygen and
because the products of fire
can escape
Myth vs Reality
Myth. Fires inside are dark
Reality.
Fire starts bright, but quickly
produces black smoke and
Complete darkness.
If you wake up to a fire you
may be blinded, disoriented
and unable to find your way
around the home you’ve
lived in for years.
Note the handprints along
the wall
Myth. You can
always outrun a fire
Reality. You can’t.
Fire can spread
extremely fast
In less than 30 seconds a small flame can get completely
out of control and turn into a major fire
Most fires in the home occur when people are asleep
Myth vs Reality
Myth. It’s only hot
near the seat of the fire
Reality. Hot gases expand
and rise very quickly
If this it what happens to
the plastic cover of an
emergency light...
The pressure inside the room
where the fire starts builds up
as the gases expand
Myth vs Reality
Myth. Fire doors are
an expensive waste
of time.
Reality. Early warning is
probably more important
but fire doors pay for
themselves as well as
saving lives
The owner of this property
doesn’t think they are an
expensive waste of time!
Myth vs Reality
Myth. Fire is deadly Reality. It isn’t a myth!
Although many more people die
from toxic fumes and inhalation
of super heated gases than die
from burnsRemember this ad
campaign?
Myth vs Reality
Current fire safety design has developed
from 2 separate pieces of Legislation
• The Building Regulations
• The Regulatory Reform (Fire Safety)
Order 2005 (The “Fire Safety Order”)
Legislation
Why two separate pieces of legislation to
deal with one hazard?
The Building Regulations deal with the design and construction of such developments.
The Fire Safety Order deals with fire safety issues in the common parts of all premises but does not apply to private domestic areas
Legislation
The Building Regulations• Means of escape
• Structural fire protection
• Surface spread of flame over
walls and ceilings
• Detection and alarm
• Access for the fire service
• All dealt with through Building
Control
Legislation
• Places a duty to carry out a risk assessment
• Make premises as safe as reasonably practicable
• Dynamic – changes depending on the risk
• Onus is on the ‘responsible person’
• Only applies to ‘common areas’ but will need to take in account risk generated in private areas
The Fire Safety Order 2005
Legislation
Why the need for fire safety regulation?
• Estimated 4 out every 5 house fires go unreported
• 55,800 reported fires in residential properties attended by Fire and Rescue Authorities in 2006
• 373 deaths
• 11,200 recorded injuries
Guidance
• Approved Document B
Volume 2 – Buildings Other
Than Dwelling Houses
• BS 9991
Fire Safety in the design,
management and use of
residential buildings
“Approved Document B
was developed for easy
and forgiving masonry
construction . .”
Approved Document B
Traditional Build
Approved Document B
Internal planning of flats
Approved Document B
Internal planning of flats
BS9991
Internal planning of flats –
Entrance from below
Smoke alarm
BS9991
Internal planning of flats –
Entrance from above
Smoke alarm
BS9991
Internal planning of flats –
Entrance from above
Heat DetectorSmoke alarm
BS9991
Internal planning of flats –
Consider this layout
Maisonettes with floor(s) at H>4.5m (Clause 9.5.2) Requirement for alternative escape(s) from non access level omitted
if either;
A protected stairway enclosure and an LD1 AFD system to BS 5839-6 subject to no floor >7.5 m above or below entrance level of maisonette); or
A protected stairway enclosure and domestic sprinkler coverage in accordance with BS 9251 or BS EN 12845 within the unit.
Flats with Galleries (Clause 9.6(e)) Additional limitation that gallery >50% of the area of the floor below
should be treated as an inner room – cannot be overcome by sprinkler protection in floor containing the gallery
Open Plan Flats• Single level only (and no galleries)
• Maximum 16m x 12m with an
enclosed kitchen
• Maximum 10m x 8m with an open (but remotely sited)
kitchen
• Minimum 2.25m floor to ceiling height
• Sprinklered (at least to BS9251)
• Fire detection and alarm to a LD1 Grade D standard
(self contained fire detectors in all rooms and corridor)
BS9991
Typical Layouts (2 bed)
10m x 8m
Open plan
Inner bedrooms
• Increased detection
• Sprinkler protection
BS9991
Typical Layouts (3 bed)
12m x 16m
AD-B compliant
Open plan
Inner bedrooms
• Increased detection
• Sprinkler protection
BS9991
General Requirements (Clause 5)
Permits the use of keys on escape windows and doors (advice to occupants) – not inferred in AD-B
Escape Windows / Doors (Clause 5.1(c))
• Min opening size 0.33m2 / 450mm as per AD B
• Cill of dormer or rooflight ≤1.5m (1100mm in AD B)
• refers to Table 1 of BS 6180:2011
BS9991
Private Balconies
Private balconies H<4.5m
• Enclosed balconies to be treated as
an inner room
• Where balconies are enclosed and
are contiguous with enclosed
balconies to other flats, the fire
resistance of the balcony structure
and compartmentation to be
maintained
BS9991
Private Balconies
Private balconies H>4.5m
• Escape through not more
than one access room
• Access room to be clearly
visible from balcony
• Travel distance limits for
single direction escape
BS9991
Communal Roof Gardens,
Balconies & Terraces
• Single direction escape of 45m
• No limit on travel with
alternative escape
• Protection of escape routes to
conform with the requirements
for either small buildings or
single stair buildings >11m
• Need to consider evacuation of
disabled where lift access is
provided
BS9991
No limitations on travel distance on deck approach but “all parts of the building need to be within 45 m of a fire main, measured along a line on which hose can be laid”
BS9991
Common Escape RoutesBalcony Deck Approach
Common Escape (Clause 7)
Balcony Deck Approach (Clause 7.3 & Fig 5) Minimum fire resistance of 30 min Walking surface to be imperforate Down-stands depths were width of
balcony is more than 2m between flats required( 0.3m-0.6m or be calculated).
Need to prove that balcony will not be smoke logged if less than 1.8m from the building facade and single direction of escape. Manual calculations acceptable
but CFD analysis may be most appropriate tool
Single direction of escape further safeguarded by external balustrade to be
imperforate. Wall, balcony soffit and balustrade
should be of a Class 0 rating.
Common Escape (Clause 7) Common Corridor Approach
(Clause 7.4) Single stair buildings > 11m
and multi stair building
Common Escape (Clause 7) Common Corridor Approach (Clause 7.4) Natural ventilation (Clause 26)
or Mechanical smoke control system option in lieu of cross-
corridor fire doors and natural vents in code compliant layouts.or
Mechanical smoke control system option may be considered to facilitate extended corridor solutions (quantitative comparative design required)or
If sprinklered throughout the block of flats (excl EC facilities),travel distances can be doubled on common escape (Clause 23.2)
7.5m → 15.0m30.0m → 60.0m
Common Escape (Clause 7)
Smoke Control in Common Corridors (Clause 7.4)
Refers to Clause 26 for details of smoke control requirements. Vent to stairs must be an AOV (1.0m2) (Clause 26.1.3)
Clause 26.1.3 (options a, b or c) all refer to requirements for common lobby / corridor
“immediately adjacent to the
stair”
NOTE 3 The shaded area indicates the area requiring a smoke control system.
Common Escape (Clause 7) Common corridor in multi stair
Common Escape (Clause 7) Common corridor in multi stair condition
Clause 26.1.4 refers to 26.1.3 for venting requirements. 26.1.3 specified corridor AOV of 1.5m2 / stair AOV 1.0m2. “however ...... vents to the exterior of the building may also be
manually operated..” (Clause 26.1.4) and 26.1.3 only refers to automatic venting over stairs
BS 9991
Ex Fig 7 of BS 9991
Common Escape (Clause 7)
Common Corridor Approach: Small Single Stair < 11m
(Clause 7.5 & Fig 8)
Criteria largely as per AD B
except for a few notable changes
Common Escape (Clause 7)
Common Corridor Approach: Small Single Stair < 11m(Clause 7.5)
Omits the requirement that ancillary areas and flats should not be on same floor level (Clause 12(b)(e))
Fig 8(b) design (two apartments per floor)
stair ventilation must be by means of an AOV and not OVs (Clause 26.1.2)
Not applicable to Open Plan living layouts (unless the lobby to the stair is maintained)
Extra Care / Special Housing (Clause 8)
Scope of BS 9991 code expanded to cover “extra care” and other special housing Max 9m travel within EC unit or provide alternative
escape. Max 7.5m travel from flat door to storey exit or cross corridor door retained
Need to consider “adequate refuge space” requirements in corridors / stairs
Evac lifts to BS9999: 2008 “where deemed necessary” Free swing / hold open devices to be used in common
circulation routes where self closers present an obstacle to movement
Extra care facilities to be sprinkler protected (Clause 23.1)
Mist Systems
Access for Fire Service (Clause 18-21) Vehicular Access – no internal fire main
(Clause 19.1.2)
Access to all parts of dwellings within 45m
(AD-B: Block of flats with no fire main requires access to within 45m of every point on the projected plan area to individual units)
Can be increased on foot of sprinkler protection and where arrival time of fire service is not more than 10mins
to 90m for houses (H<4.5m)
to 75m for houses / flats (not more than one floor above 4.5m)
Arrival time subject to consultation with Fire Service
Access for Fire Service (Clause 18-21)
Residential Fire Fighting Shaft (Clause 19.2)
Stair door to be FD60S
Apartment corridor to serve as
fire fighting lobby
Can use additional fire mains
in escape stair to meet
coverage requirements;
60m from outlet in fire shaft
45m from outlet in escape stair
Active Fire Protection (Clause 22-26)
Fire Alarm System (Clause 22) No requirement for common AFD system (Clause 22.1) other
than to initiate smoke control systems
Clause 26.2.3.4 “Unless a simultaneous evacuation arrangement is deemed appropriate, there should be no sounders attached to the smoke detectors within common parts. NOTE 2 The purpose of smoke detectors is to operate the smoke control system, not to raise an alarm”
Only non residential areas in mixed use buildings need have AFD fitted
Risk assessment approach considered appropriate in determine AFD requirements for communal areas / roof gardens associated with sheltered housing
Active Fire Protection (Clause 22-26)
Sprinkler & Watermist Systems (Clause 23)
Sprinklers recommended for Buildings > 30m (and possibly H>18m) – BS EN 12845 Extra Care developments
Sprinkler protection trade-offs (discussed already) 3 storey house with open plan ground floor (Clause 6.3) 4 storey house with no 2nd means of escape (Clause 6.4) Open plan flats (Clause 9.7) Increased distance vis vehicular access (Clause 19.1.2) Increased travel in common corridors (Clause 7.4) Reduced boundary distance by half (Clause 29.4.2)
Active Fire Protection (Clause 22-26)
Sprinkler & Watermist Systems (Clause 23)
Watermist gets conditional approval in BS9991 subject to agreement of the relevant enforcing authority (Clause 23.1)
Needs specific scenario testing to prove viability and effectiveness of each system
Active Fire Protection (Clause 22-26)
Manual Fire Fighting equipment (Clause 24)
Not required in common areas (unless risk assessment dictates otherwise)
Employed in “higher fire risk areas” in sheltered housing
Special Risk Protection (Clause 25)
“Where a common stair forms part of the only escape route from a flat, unless it is designated as a small single-stair building in accordance with 7.5, it should not also serve any covered car park, boiler room, fuel storage space or other ancillary accommodation of similar fire risk.”
At odds with 13.2 which permits sprinklered basement car park for single stairs buildings > 11m ?
Any Questions