Fire Protection in Buildings

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Nov 26, 2013 (3 years and 8 months ago)

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NEBOSH
Fire
Certificate
Element 4 Part 1

Issue

Oct 2011

Fire Protection in Buildings

Building Regulations 2000


In general covers new builds and modifications


Schedules A
-
K contain information on structures, fire,
moisture, toxic substances, noise, ventilation, hygiene and
drainage.


Part
B (Fire Safety) of the Building
Regulations and Approved Document B

Volume 1
-

Dwellinghouses

Volume
2



Buildings Other Than
Dwellinghouses

Flats

(including multi
-
storey flats &
mixed
-
use buildings)

can be found in
Volume 2

Schedule B Fire

B1

Means of warning and escape

B2

Internal fire spread (linings)

B3

Internal fire spread (structure)

B4

External fire spread

B5
Access facilities for the fire service


Appendices regarding fire performance materials with
regards test methods

Part B (Fire Safety) of the Building
Regulations and Approved Document B

Fire Resistant Properties

of

Common Building Materials


Resistance to collapse
Load Bearing


Fire & Smoke Penetration
Integrity


Transfer of Excessive Heat
Insulation


Resistance of Fire Doors
Stop the spread
of smoke, fumes or heat.

Elements of a Structure



a.

A member forming part of a structural frame of a
building or any other beam or column



b.

A load bearing wall or load bearing part of a wall



c.

A floor



d.
A gallery



e.
An external wall



f.
A compartment wall

Timber


Timber burns at the surface


Does not expand when heated


Does not collapse suddenly


Fire resistance depends on
:
-


Thickness & cross sectional
area


Tightness of joints


Type
of
wood


Treatment



Reinforced Concrete Frames



Types:
-

Reinforced, Pre
-
stressed
(pre
& post tensioned)


Resistant to fire


Fire resistance depends on type &
thickness of concrete used & protection
afforded by the concrete to the steel


Brickwork &
Blockwork


Resistant to fire


Resistance depends on
:
-


Thickness


Plastering or coating


Whether load bearing or not


Cavities within the bricks or blocks



Structural Steel


Non
-
combustible


Steel expansion causes buckling can affect
stability of building


Steel looses strength in a fire


Sheet Materials


Fibre board can be fire resistant if
impregnated


Plaster boards retard fire spread


Plywood/chipboard depends on
properties of wood


Plastic has little fire resistance


Glass breaks unless wired or tempered


Lining Materials


Mostly non
-
combustible


Some older types may contain wood
dust


Plaster (calcium hydroxide) has good
fire resistance


B2 Internal Fire Spread
(
linings
)


To inhibit the spread of fire within the
building the internal linings shall resist the
spread of flame over their surfaces and if
ignited a rate of heat release or a rate of
fire growth which is reasonable in the
circumstances.

B3 Internal Fire Spread
(
structure
)


The building shall be designed and
constructed so that in the event of fire, its
stability will be maintained for a reasonably
period.


Consider:


Design


Materials


Compartmentation


Shafts


Concealed spaces (cavities)


Protection of openings and fire stopping


Compartmentation


To prevent fire, heat, and smoke from spreading beyond locations of origination



Building elements such as fire walls, fire dampers, and fire doors, are designed
to seal off one location from the next.



Increases the safety by allowing evacuating building occupants because smoke
and fire are not able to escape into exit passageways.



Containment of fire and smoke reduces property damage and prevents small
fires from growing.



In order for compartmentation efforts to be effective

fire barriers must be maintained

Compartmentation


30 min fire resistance


Maintains
building
structure


Allows sufficient time to
escape


Minimises
destruction


Assists
firefighting

To prevent fire, heat, and smoke from spreading
beyond locations of origination.

Cavity Barriers

Compartment Walls/ Floors Junction

Openings & Voids


These can eliminate the protection afforded by
the compartment


Any opening will allow fire to spread quickly


Voids
eg

cable ducts, suspended ceilings &
floors provide ready routes for fire spread


“Fire Stopping” ensures barriers to fire spread
are replaced

B4 External Fire Spread


The external walls of the building shall
adequately resist the spread of fire over the
walls and from one building to another, having
regard to the height, use and position of the
building.


The roof of the building shall adequately resist
the spread of fire over the roof, from one
building to another, having regard to the use
and position of the building.

B1 Means of warning and escape



The building shall be designed and
constructed so that there are
appropriate provisions for the early
warning of fire, and appropriate
means of escape
(MOE)
in case of
fire from the building to a place of
safety and effectively used at all
times.


B1 Means of warning and escape


B1 will be met if
:


There are routes of sufficient numbers and
capacity which are suitably located


The routes are sufficiently protected from the
effects of fire by enclosure where necessary


Routes are adequately lit and sign posted


Appropriate facilities to either limit the ingress of
smoke to the escape routes or to restrict the fire
and remove the smoke


Arrangements for early warning


Protection of escape routes


Means Of Escape


Structural means forming an integral part of the
building whereby persons can escape from fire
by their own unaided efforts to a place of safety



Consider


structure, travel, fire, place of
safety.


Main principles BS5588 and
Acop’s

and The
Building Regulations 2000

Strategic Factors Affecting Means
Of Escape


Occupancy


Construction


Time of evacuation


Exits


Travel Distance


Management

Maximum Travel Distances

Where more than one route is available


25 m


high risk area


45 m


normal risk area


60 m


low risk area


Where only single escape route is available


12 m


high risk area


25 m


normal risk area


45 m


low risk area


Escape Routes


Stairways, corridors and areas near the fire exits
should be kept clear of obstructions and material
which can catch fire.


The escape route should lead to a final exit and a
safe place.


If the stairway is not protected, the travel distance
should be in line with those for single escape routes
and the final exit should be easy to see and get to
from the stairway at ground
-
floor level.


High
-
risk rooms should not generally open directly
into a fire
-
protected stairway.


Alternate means of escape usually required

Stairs & Corridors


Minimum width
800mm stairs
(increases with number of
persons)
but not to exceed 1.4m unless central
handrail fitted


1.2m
corridors


One stairway up 4 storeys only


Stairways to have handrails


Treads and risers of stairs of correct dimensions


Structure 30
mins

fire
resistance

Stairs, Corridors and Passages


Fire Protection 30 minutes minimum


Be
ventilated


Sub
-
divide
corridors (If longer than
12m)


Not cause bottle necks


Height
2m


Be continuous to the exit point


Correct lighting


Management actions to maintain MOE




Emergency Lighting


Aim


To indicate clearly the escape route


Illuminate routes to allow safe movement


To ensure call points and equipment can be located


Consider natural light
-

day/night


Siting


Escape route lighting


Open area lighting


anti
-
panic lighting


High risk lighting


Different types


Maintained


Sustained


Self contained


Low level lighting


Testing


Daily, Monthly, 6 monthly


Signage


The H&S (Safety Signs & Signal)
Regs

96


Two types
-

EC Pictorial & BS5449 Pictorial and
words


Types Include
-


Directional arrows, equipment, alarms, assembly points


Read from both sides


Not
obscured

Fire Doors


BS 476


Does not obstruct route when open


Self closing with smoke stops


Three hinge, Colour coded
rawl

plugs.
i.e

FD 30/30


Width 850 if more than 50 persons


Smoke sealed


intumescent

strips


30 minutes fire resistance


Easily opened and in direction of travel


Magnetic hold
-
backs are okay


Final exit to unobstructed place of safety


Never locked


Have visibility panels


45 degree rule


Roller shutters should be capable of manual operation


Amount


60=1 600=2 More than 600=3




APPROVED DOCUMENT M
-

THE
BUILDING REGULATIONS


1
.
general

guidance

on

Vision

Panel

dimensions,

however

if

Vision

Panels

form

part

of

a

fire

resisting

door

set

then

the

area

of

the

glass

may

be

determined

by

the

fire

resistance

properties

and

the

manufactures’

s

specifications

etc
.

2
.
All

door

glazing

on

traffic

routes

and

public

areas

should

be

Safety

Glazing

Standard,

in

addition

to

any

fire

resistance

required
.

Final Exit Doors


Open in direction of exit (outwardly)


Have "push bar" openers (panic bolts)


Be marked "
FIRE EXIT
"


Do not open directly to stairs


External area free from vegetation and
other obstacles


Place of Safety

MOE For Vulnerable People


Evacuation lifts, refuges and chairs


Use of graphic, aural, tactile
signage


Personal Emergency Evacuation
Plan (PEEP)

Fire Detection


Smoke Detection


Optical or ionisation


Optical detects obscuration of light by smoke


Ionisation detects by change in electrical charge


Heat Detection


Fixed rate or temperature rise


Used where there is heat under normal conditions
(kitchens)


Flame Detection


Infra
-
red or ultra
-
violet


Usually used with other types


Ionisation Smoke Detector


Americium 241 enables
current to flow between
the inner and outer
chambers.


As smoke enters the
detector an increase in
voltage occurs between
the two chambers.


The voltage increase
triggers the detector at
a preset threshold.


Ionisation detectors
respond well to fast
-
burning fires

Optical Smoke Detector


smoke from a fire
scatters the light from
the LED


if smoke seen on the
two following pulses,
the alarm lights up.


optical smoke
detectors respond
well to slow
-
burning
fires.

Heat Detector


Twin
thermistors

detect change in heat


Difference in temperatures triggers the alarm


Static response detectors have one sensor at
preset temperature


They have wide openings to allow good air
movement over the sensing
thermistor

Flame Detector


A flame detector is designed to detect ultraviolet
(UV) or infra
-
red (IR) radiation emitted by fire.


Dual IR flame detectors are sensitive to low
-
frequency, flickering infra
-
red radiation.


Detector can operate even if the lens is
contaminated by a layer of oil, dust, water
vapour or ice.


Flame detectors are effective in protecting areas
where flaming fires may be expected.


Alarm Systems


Components


Automatic
detector


Spot (static)


Line (linear heat laid around an area)


Beam (of light IR large areas)


Sampling (pipe work pulling air
through a detector)


Scanning (moving/sweeping a large
area)



Manual call point



Alarm sounder



Control panel

Categories of Fire Alarms &
Detection Systems


Systems generally designed & installed to BS 5839


Property risk/protection
(to summon the Fire & Rescue Service in
the early stages of a fire)



Category P1 installed throughout all areas of the building
.


Category P2 Systems installed only in defined parts of a
building.

Life Risk/ Protection


Category
M

Manual system
(call points & sounders only)


Category
L

Automatic fire detection systems intended for the
protection of life


L1

Installed throughout all areas of a building


L2

Installed only in defined parts of the building


L3
Designed to give a warning at an early enough stage to enable
occupants to escape safely before routes are impassable due to fire,
smoke or toxic gases. (other than possibly those in the room of the fires
origin)


L4
Installed in escape routes comprising of circulation areas (stairways
and corridors) Objective is to provide warning of smoke within escape
routes.


L5
Systems in protected areas and or location of detectors designed to
satisfy a specific fire safety objective other than the above categories.

Fire Alarm Zoning


Zones are a convenient way of dividing up a building to
assist in location of a fire.


Zones are not physical features (
normally the zone boundary
coincide with walls, floors and fire compartments)


Zone basic rules
:


Single zone should not exceed 2,000m
2


Two faults should not remove protection from an area > 10,000m
2
(for addressable systems) Addressable= Gives unique ID to the
actuating device detector/call point which has been activated.


Floor area < 300m
2
regarded as one zone.


Total floor area > 300m
2
zones restricted to single floor levels


Exception to above: stairwells, lift shafts or other vertical shafts
should be considered as one or separate zones


The max distance travelled within a zone to locate the fire should not
exceed 60m.


Alarm Signalling


Objective to warm occupants of a fire situation


One sounder located near the control panel on a
separate circuit


Sounders should sound similar to avoid confusion


Minimum of 65db in general areas or 5 db above
background noise.


High noise areas visual indication may be required.


Sleeping 75db at
bedhead

(30 db should be allowed per door
so sounder per bedroom is recommended)


Impaired hearing other means of signalling may be
required



Alarm Receiving Centres


Permanently manned
(normally a commercial organisation)


Upon receipt of a fire signal notify the fire service



Factors in the Selection of Fire
Alarm & Detection Systems


Life Risk


Process Risk


Behavioural issues


Social Behaviour Minimising false Alarms
(
unwanted
alarms, Equipment false alarms malicious alarms)


Requirements for Vulnerable People
(disabilities and/or
mobility problems
)


Requirements for
Maintenance & Testing


RRFSO 2005 States
“ equipment & devices are subject to
suitable system of maintenance and maintained in an efficient
state.... Good repair”


One regime to comply with is would be:


Daily Check
System is not indicating a fault if required
corrective actions are taken.


Weekly Check Test the system by operation of a call
point
(different one each week)


Periodic

Subject to RA (but should not exceed 6 months)


Check system log, visually inspect all items of
equipment(obstructed or inappropriate due to change of use),
amount of false alarms, standby power, remote signalling ,any
other checks required (beam detectors for alignment etc) all call
points over the 12 months plus cabling, programming and
audible checks.