Roof Operations- by Craig Reed.pdf

ROOF OPERATIONS 

by 

Firefighter Specialist 

Craig Reed

PROGRAM OUTLINE 

• Section I 

– Part One- Introduction 

– Part Two- Fire Behavior 

• Section II 

– Part One- Light Weight vs. Conventional 

– Part Two- Roof Styles and Design 

• Section III 

– Part One- Fire Ground Tactics 

• Section IV 

– Part One- Ventilation Methods

Section I 

Part One 

INTRODUCTION

• Objectives: 

– To provide a basic overview of roof 

operations 

– To allow for discussion of advanced fire 

ground tactics and strategies

• A considerable portion of the 

annual loss of life and property is a 

direct result of the lack of timely, 

effective ventilation

•80% of all fire fatalities are due 

to smoke inhalation

• More than one-half of the nations 

fire loss is a direct result of smoke 

and heat damage

• Ventilation has a direct effect on 

all aspects of fire fighting 

strategies

Section I 

Part Two 

Fire Behavior

FIRE BEHAVIOR 

•Phases of Structure Fires 

•Thermal Balance 

•Flash Over 

•Back Draft

PHASES OF STRUCTURE FIRES 

• Structure fires progress through three 

basic phases: 

– Incipient/Beginning Phase 

– Steady State/Free Burning Phase 

– Hot Smoldering Phase

• Phases of Fire 

INCIPIENT PHASE 

• Oxygen content approximately 21%. 

• Carbon dioxide, sulfur dioxide, carbon 

monoxide and water vapor produced. 

• The flame temperature can be above 1000 

degrees, while room temperature may only 

be slightly elevated.

• Phases of fire 

STEADY STATE 

• Adequate oxygen and fuel sustain freeburning 

and fire growth to the point of 

full involvement of area/room. 

– Thermal Balance/Mushrooming 

– Rollover 

– Flashover

STEADY STATE


• Mushrooming 

STEADY STATE 

– Smoke and gases are heated. 

– If confined to a room or building, they will rise 

to the uppermost level. 

– Cooler air is displaced down towards the fire, 

providing oxygen and sustaining combustion. 

– As circulation occurs, heated smoke and gases 

build internal pressure that continue to rise 

and spread laterally.


STEADY STATE 

Temperatures can vary considerably 

from floor to ceiling 

Note absents of heat/fire 

damage at lower levels


STEADY STATE 

Temperature variances pose 

significantly different 

challenges to fire crews 

Heavy charring at ceiling level 

causing structural compromise


• Rollover 

STEADY STATE 

– Fire gases accumulate at uppermost levels 

– Gases are heated to their ignition 

temperature 

– Gases ignite and “roll” or “float” across the 

upper most level of a room or area 

– Fire acts erratic and advances rapidly


• Flashover 

STEADY STATE 

– A simultaneous ignition over the surface of 

the room or area. 

– Occurs when the heat from the fire raises 

the temperature of the contents to their 

ignition temperatures. 

– The ignition happens in an instant. 

– Effects may be deadly to firefighters

Flashover


HOT SMOLDERING PHASE 

• If the free-burning state remains un-vented, 

the fire progresses into the decay phase. 

– Low oxygen levels with little or no flame production. 

– Temperatures in excess of 1000 degrees. 

– Dense black smoke, that pressurizes the area. 

– Intense heat continues to vaporize lighter fuels. 

– Gases are produced which greatly increase the 

chance of a backdraft.

HOT SMOLDERING PHASE


BACKDRAFT 

• Backdraft 

– A confined area that is teeming with 

pressurized, heated flammable gases 

– The introduction of oxygen to this fuel-rich 

environment will result in an explosion of 

significant intensity 

– Effects may be deadly to firefighters


Offensive Ventilation 

• Vertical ventilation 

– Most effective tactic in preventing flashover 

and backdraft 

– Reduces the effects of rollover by 

channeling smoke 

– Reduces the effects of steam on fire attack 

crews


Offensive Ventilation 

• Firefighter Concerns 

– Controlling fire behavior is the ultimate 

goal of the vent group 

– Effective control will 

• Save Firefighter lives 

• Increase safety of interior crews 

• Reduce civilian fire related death/injury 

• Reduce property damage 

• Improve “knock down” times

End 

Section I 

Part One 

Please continue Roof Operations presentation 

by viewing 

Section II 

Part One 

Light Weight vs. Conventional Construction

Part II 

ROOF CONSTRUCTION 

• Conventional Vs. Lightweight 

• Roof Styles 

• Roof Design

Roof Construction 

• The firefighters ability to safely and efficiently 

ventilate a building through the roof will 

depend to some degree on his understanding 

of roof construction 

• It is essential that firefighters become familiar 

with the existing and newly constructed 

buildings within their response area

Roof Construction 

• Conventional 

VS 

Lightweight

CONVENTIONAL 

CONSTRUCTION

• Roof Construction 

Conventional Construction 

• Structural members depend on size for 

strength. 

• Less surface area exposed to fire. 

• The larger the size of a structural 

member, the longer it will take to fail 

when exposed to fire. 

• Potentially longer burn time results in a 

greater window of safety for fire 

fighters.


Arched Trusses 

• Buildings built during the 1930‟s and 

1940‟s commonly used truss 

construction. 

• Truss members have the same strength 

relationships as lightweight only much 

stronger.


Bridge Trusses 

• Buildings built in the 1920‟s-1940‟s not 

as common as the arch 

• Roofs vary in size and slightly in design 

• Top surface is basically a flat roof


Conventional Residential


Conventional Residential


RAFTERS AND SPACE 

SHEETING


Conventional Construction 


– Generally sound construction 

– Strongest areas of these roofs are ridges, 

hips, valleys, over trusses and where 

rafters cross outside walls 

– Size of structural member dictates fire 

exposure time prior to failure 

– Heat holes are acceptable and preferred 

with this type of construction


LIGHTWEIGHT 

CONSTRUCTION


Lightweight construction: 

• Does not derive its strength from size. 

• Strength obtained from multiple 

members in compression and tension. 

• Involves the use of less fire resistive 

materials. 

• Provides less time to ventilate before 

the roof becomes unstable.


Lightweight Construction 

• General Rules 

– Expect early and complete collapse 

– No heat holes 

– Cut vent holes well ahead of fire 

– 3/8-1/2” decking offers little resistance to fire 

– Structural compromise may go undetected from 

roof 

– Time on these roofs is very limited


Major types of Lightweight 

roof construction 

• Metal Gusset Plate 

• Wooden “I” Beam 

• Open Web Truss 

• Open Web Steel Joist 

• Panelized


Metal Gusset Plate Trusses: 

• Common in residential and commercial 

buildings. 

• Usually 2” x 4” lumber butt jointed and held 

together by metal gusset plates commonly 

known as “gang nail” which are 3/8” in depth. 

• Characterized by a top (compression) chord 

and bottom (tension) chord. 

• Spans up to 80‟ with trusses 2‟ on center


Lightweight Commercial 

• Metal gusset plate


Metal Gusset Plates


Metal Gusset Plates 

Heat causes gusset plates 

to pull away


Metal Gusset Plates 

–Burn test-structural collapse 

1min. 20 sec. with direct flame 

impingement


Metal Gusset plates 


– Gusset plates increase charring at joints 

resulting in failure 

– Chord or web failure causes truss failure 

– Open space between chords promotes fire 

spread


Wooden “I” Beam: 

• Top and bottom chord of 2” x 3” or 2” x 

4”. 

• The stem is normally 3/8” plywood or 

OSB glued in place. 

• Common spacing is 2‟ on center. 

• Strongest location is where the roof 

meets the exterior wall.


Wooden “I” Beam


Wooden “I” Beam 

• Burn test-structural collapse 3 min. 15 

sec. With direct flame impingement.


Wooden “I” Beam 


– Stem has very little relative mass and 

burns to failure quickly. 

– “Poke through” construction reduces truss 

strength and promotes fire spread


Open Web Trusses: 

• Wooden top and bottom chord cross 

connected by steel tube web members. 

• 2x3 or 2x4 chords with spans of up to 

70‟. 

• Common spacing is 2‟ on center. 

• Strongest location is where the roof 

meets the exterior wall.


Open web 

Steel pins conduct heat 

Laminated cords allow for 

glue failure 

“Free hanging” bottom cords


Open Web Trusses: 

• Structural collapse 4 min. 30 sec. With 

direct flame impingement.


Open Web Trusses 

• Firefighting Concerns 

– This is the most lightweight of truss 

construction 

– Steel is good conductor of heat 

– Open space between cords promotes fire 

spread


Open Web Steel Joist 

• Steel top and bottom chords usually 

1/8” angle iron 

• Webs 1/8” angle iron or 5/8” solid bars 

• Corrugated metal decking is commonly 

used with these trusses 

• Often configured in a “panelized” 

fashion


Open Web Steel Joist



With steel decking 

With wood decking




– Steel exposed to heat can distort and fail 

– Consider rotary saws with carbide blades 

for cutting steel decking 

– Fire may travel in horizontal openings of 

metal decking


Panelized Construction 

• Consist of large, laminated beams spaced 12‟ 

to 40‟. 

• Beams can span well over 100‟. 

• Purlins with metal hangers on 8‟ centers. 

• Purlins may be timber or truss design 

• 2” x 4” rafters 2‟ on centers. 

• Decking is usually 1/2” plywood.


Panelized Construction


PANELIZED SKELETON



Purlins 

Beam 

Rafters


• Panelized roofs: 

– Structural collapse 5 min. 20 sec. With 

direct flame impingement




– Steel beam supports weaken and fail 

resulting in sudden collapse of large 

portions of roof 

– Foil insulation promotes fire spread 

– Strongest areas are over beams, purlins 

and perimeter of building

ROOF CONSTRUCTION 

Roof Styles and Designs


There are three basic styles 

of roof design 

• Pitched roofs 

• Arched roofs 

• Flat roofs


Pitched Roof Design 

• Gable 

• Hip 

• Shed 

• Bridge Truss 

• Mansard 

• Gambrel


Gable 

• Basic A-frame design with the roof pitched in 

two opposing planes. 

• May utilize conventional or lightweight 

construction. 

• Covered by shake, tile, rock, composition, 

etc. and supported by sheathing or plywood.


PITCHED ROOF LINES


Gable Roof with dormers


Hip 

• Similar to the gable roof, but lacks the A- 

frame configuration. 

• Two sets of opposing pitches where the roof 

slopes down to meet every outside wall. 


construction.


Hip Roof


Shed 

• This style is essentially half a gable 

roof. 


construction. 

• Often used with other roof designs


Shed 

Lantern 

True shed 

Saw tooth


Bridge Truss 

• Easily identified by its characteristic 

sloping ends. 

• Wooden truss members are 2” x 12” 

and constitute a heavy grade of 

construction. 

• Rafters are 2” x 6” or larger and 

covered by 1” x 6” sheathing and 

composition.

Bridged truss concealed by 

supported facade


Bridged Truss


Bridge Trusses


Bridge Trusses


Mansard 

• This roof has a double slope on each of its 

four sides. 

• The lower slope is steeper than the upper 

slope. 

• Upper slopes may create hip, ridge or flat 

roof 

• Usually bridge truss construction


Mansard

Gambrel 

• Pitched roof with two planes on each 

side 

• Lower planes are steeper than the 

upper planes 

• Difficult to ladder, roof ladder usually 

required 

• Lower plane may make up interior wall

Gambrel


Arched Roof Design 

• Ribbed arch 

• Lamella roof 

• Bowstring arch


Ribbed Arch Truss 

• Similar to Bridge Truss except that the top chord 

is arched. 

• Large wooden members of 2” x 12” to 2” x 14”. 

• Rafters (2” x 6” or more) are covered with 1” x 6” 

sheathing and composition roofing material. 

• Early collapse is not a primary concern.


Arched Truss Roofs


Arched Trusses


Arched Truss in various 

configurations


Arched Trusses


Arched Truss 

– This roof predictably fails in sections. 

Pilasters indicate location of trusses


Lamella Roofs 

• Egg-crate, geometric or diamond-patterned 

roof. 

• Roof decking is 1 x 6 sheathing. 

• Common on gymnasiums, supermarkets and 

recreational buildings. 

• Total roof collapse may occur if fire removes 

more than 20% of roof structure. 

• Failure results from the “domino effect.”


Lamella Roof


Lamella Roof

• Lamella continuous arch 

Lamella 

“Tell-Tail sign” 

• Bridge truss “trailing ends”


Bowstring Arch 

• Similar in appearance to ribbed arch and lamella 

roofs, yet significantly different. 

• Metal tie rods with turnbuckles offer lateral 

support and ensure that arch roof does not push 

the exterior walls outward. 

• Rafters (2” x 10”) are covered with 1” x 6” 

sheathing and composition roofing material. 

• Primary hazard is early failure of the metal tie 

rods and turnbuckles.


Bowstring Arch 

Turnbuckle 

Tie rod Anchor


Flat Roof Design 

• Popular style for a wide variety of structures. 

• Flat roofs are the most deceiving style of roofs. 

• Although it is simplistic in appearance, it varies in 

construction methods and is often difficult (from the 

exterior appearance) to determine the method 

utilized, i.e.. Conventional/lightweight.


Flat Roof Design 

• Conventional 

• Wooden “I” beam 

• Open web 

• Open web bar joist 

• Metal gusset plate 

• Panelized (may be combined)

Conventional construction Flat 

residential


Flat commercial


Flat Commercial

Flat Commercial with high 

parapets


Roof Dead Loads

You never know what you might 

find

PART III 

FIRE GROUND TACTICS 

• Tactical Considerations 

• Size Up 

• Diagnostic Methods

Tactical Considerations 

• Ventilation is the first step in gaining 

positive control of a fire building. 

• Ventilation allows all subsequent 

operations such as search, rescue and 

fire attack to be much more safe and 

efficient.


• The decision is not, “should we ventilate,” 

but rather, “what type of ventilation should 

we use and how aggressive should we be.”


• Life hazard/Search and rescue 

• Location and extension of the fire 

• Type of construction (strengths/weakness) 

• Means of ingress/egress 

• Time


Life hazard/Search and rescue 

• Immediate ventilation 

• Facilitate search and rescue 

• Route heat and smoke away from operation 

• Always consider benefit to attack crews


“An aggressive interior attack always 

has an increased life hazard risk”


Location and extension of the fire 

• Risk Vs Gain 

• Offensive/ Defensive 

• Self vented 

• Coordination with fire attack


Type of construction 

• Strengths and/or weakness 

• Modular/ Garden Style/ Center Hallway 

• Conventional: Heat hole over area of 

involvement 

• Lightweight: Vent hole ahead of fire 

• Time/Manpower constraints



• Garden Style



• Center Hallway



• Modular


Means of ingress/egress 

• LCES 

• Identify path of travel 

• Identify work area 

• Two means of egress


Path of Travel 

• Cross Gable


Path of Travel 

• Hip


Time Considerations 

To accurately estimate the amount of 

time that a roof can be considered 

structurally sound the following 

factors must be considered


Time Considerations 

• Type of construction 

• How long the fire has been burning 

• Fire intensity/fuel load 

• Your experience 

• Frequency of training


“What the ventilation group 

needs most and almost never 

has is the commodity of time”

• Ventilation Size-Up 

“We‟re Go‟in to the Roof”!


Ventilation Size-Up 

• Type and age of occupancy 

– Residential Vs. Commercial 

• Garden Style/ Center Hallway/ Modular 

• Type of construction- 

– Conventional Vs. Lightweight 

• Location and extension of fire 

– Fire intensity and fuel load 

• Type of roof 

– Style and Design 

– Size 

• Special Hazards 

– Dead Loads 

– Utilities 

– Sky Lights

Ventilation Size-Up


Basic equipment requirements 

• Minimum of two-person teams. 

• Full PPE‟s and SCBA. 

• Pick head axe and power saw. 

• Rubbish hook, pike pole, or other 

suitable tool. 

• Communication Equipment.

Laddering


Laddering 

• Consider the areas that offer strength, routes of 

travel and no horizontal openings: corners, 

pilasters, hips, etc. 

• Minimum of two ladders to a roof, providing a 

primary and alternate way to exit. 

• Determine the roof line and its effect on ladder 

operations. Additional ladders needed?


Ground and Roof Ladders


Extension Ladder


Ladder Options


Choose the right tool for the job! 

• 20” straight is the ladder of choice for flat residential


Correct ladder placement is 

critical


Aerial Ladder


Aerial Ladder 

• Can reach areas that ground 

ladders might not be able to 

• Can be raised quickly by one 

person 

• No need for tie off/footing 

• Greater stability, visibility


Reading the Roof 

• What is the size and type of roof? 

• Is any portion of the roof sagging? 

• Are there ventilators or smoke vents, and are 

they issuing smoke and/or fire? 

• Is fire showing through the roof? 

• Does the roof utilize material which may be 

difficult to traverse? 

• Are additional ladders needed. (steep 

pitch/parapets)

• Diagnostic Methods 

Indicator Holes 

• Kerf Cut 

– Chainsaw 

– Axe blade/pick 

• Triangle cut 

– Chainsaw 

– Axe 

– Leave a trail


“Kerf Cut” 

A slit or notch made by a saw or other 

cutting tool


Kerf cut using chainsaw


Apply chain brake and plunge 

saw to remove insulation


Triangle indicator using 

chainsaw

Triangular indicator hole using 

an axe

Remove insulation using axe 

handle or other suitable tool

Diagnostic Methods 

• Determining the type of roof 

– The following will assist in determining the 

type of roof surface that will support a 

ventilation operation: 

• Pre-fire planning. 

• Plug cut. 

• Axe bounce. 

• Inspection cut (45 degree).


Pre-Fire Planning/Training 

• A valuable aid in determining what types of 

roofs are in a company‟s district 

• Ventilation operations are simplified when 

personnel have prior knowledge of basic 

types of roofs and their construction. 

• Train using existing building with-in your 

district

“Train as if your life depends on it, 

Because it does!”


Plug cut 

• A small triangular piece of 

roofing material is removed 

• Reveals the type of roof 

decking 

• Can aid in determining rafter 

direction 

• Metal joists are 90-degrees 

to corrugations in metal deck 

roofs. 

• Rafters are 90-degrees to 

the grain of sheathing


Axe bounce 

• Utilized to determine the direction of wood 

sheathing. 

• Strike the roof at 90-degrees or parallel to 

any exterior wall. 

• Axe will “stick” when parallel to the grain and 

bounce when 90-degrees to the grain. 

• Will also determine the direction of the rafters 

underneath the sheathing.


Inspection cut 

• Approximate area to be vented. 

• Determine size and direction of rafters. 

• Indication of fire intensity in rafter/truss area. 

• 45 deg. To outside wall. 

• One foot past structural member. 

• Complete triangle. 

• Remove piece over rafter.

Inspection hole 45 deg. To outer 

wall. Continue until rafter is rolled

Cut triangular shaped hole, 

ensure all cuts intersect


Inspection Hole


Inspection Holes

PART IV 

VENTILATION METHODS 

• Heat Holes 

• Directional Openings 

• Making the cut

• Ventilation Methods 

Heat hole 

• Close to area of involvement 

• Most direct path for heat and smoke 

• Dangerous procedure 

• Not recommended with lightweight


Pitched roof Attic fire 

Heat Hole near the peak or over the fire?


Heat hole, flat roof


Directional Openings 

• Strip ventilation opened ahead of the fire. 

• Designed to change the horizontal direction 

or extension of fire, heat and smoke. 

• Reduces or curtails horizontal spread 

• Effective ventilation opening


WIB STRIP CUT AGAINST 

CONSTRUCTION

Directional Openings

VENTILATION METHODS 

“Making the Cut” 

• Center rafter 

• Dicing 

• Louver 

• Pull Back


Center Rafter Technique 

• Most universal cutting technique 

• Building block of most all vent holes 

• Hole size easily increased /extended 

• Sections are cut so that they are nailed 

to only one rafter 

• Holes should begin and end at rafters 

whenever possible to prevent „spring 

boards‟

Center Rafter

Center Rafter

Center Rafter

Intersect all cuts to facilitate 

removal of decking

Center Rafter

Center rafter holes can easily be 

extended


Dicing Technique 

• Head cut across several rafters 

• Score cut used to identify rafter location 

• Dice cut between rafters/score marks 

• Decking can be pulled back or louvered

Multiple rafters can be rolled and 

scored to allow for dicing later

“Dice” between rafters/score 

marks

Dicing


Louvering Technique 

• Most effective with plywood decking 

• Less effective than complete removal of 

decking 

• Carefully position deck to form “louvers” 

to facilitate smoke removal 

• Do not force decking into vent hole 

• Note wind direction/position on roof

Panels can be louvered or 

removed 

Wind


Louvering Technique


“J” Hook 

• “J” hooking with the appropriate tool 

separates decking from the center 

rafter 

• Creates pile of decking at base of hole 

• Takes advantage of entire opening

• Ventilation Methods

Rubbish hook, pike pole, axe or 

other appropriate tool can be used


Pull-back Method 

• Can be used on all decking types 

• Completely remove decking from vent 

opening 

• Prevent decking from falling into vent 

hole 

• Preferred method for heat holes

“Pull back” decking to open vent 

hole and create workable pile of 

material



• Always work from primary structural 

members ie. (beams, purlins, 

parameter) 

• Variations of a “center rafter” can be 

used on most roofs 

• Vent hole in panelized construction may 

require cutting through rafters.



• Choose vent hole type based on 

manpower, team location and 

“ventilation goals” 

– Fold Back 

– Drop Panel 

– Panel Louver 

– Strip from beam 

– Strip from purlin

Panelized roof showing beams 

and purlins

PANEL FOLD BACK 

• Minimum 5 personnel 

– 1-Look out/ safety 

– 2-Sounders 

– 2-Sawmen 

• Equipment needed 

– 2 Saws 

– 2 Rubbish hooks 

– Communication

PANEL FOLD BACK 

• 1 Sounder, 1 Saw man per purlin 

• Personnel exchange tools 

• Saw men cut/intersect top cut 

• Saw men cut relief for rubbish hook 

• Saw men cut parallel cuts through first 

rafters, stop at second rafter 

• Sounders fold panel back 

• Repeat operation

PANEL FOLD BACK

DROP PANEL 



• Saw men cut parallel cuts through 

rafters (no top cut) 

• Sounders back-up Saw men 

• 1 Saw man cuts bottom cut at beam 

• Multiple panels drop into building

DROP PANEL

Drop Panel

DROP PANEL

PANEL LOUVERS 



• Saw men cut/intersect top cut 

• Saw men cut parallel cuts. Roll/score rafters 

• Saw men cut/intersect dice cuts 

• Exchange tools, position louvers

Panel louvers working from 

purlins against construction

Panel louver

LOUVER FROM BEAM 

• Sounder/Saw man single file on beam 

• Team #1 exchange tools 

• Team #2 cut parallel cut past center rafter 

• Team #1 cut top cut/ parallel cut and dice 

every 8 feet 

• Sounder positions louvers

LOUVER FROM A BEAM

LOUVER FROM A BEAM

Louver from purlin 

• Sounder/Saw men single file on purlin 

• Team #1 exchange tools 

• Team #2 cuts parallel/scores rafters 

• Team #1 cuts top, parallel and bottom cuts 

• Sounder positions louvers

Strip/louver from purlin

The End 

“Keep on Training”

Special Thanks To 

Fire Station 170 and 181 

For their dedication and hard work

“PAIN IS TEMPORARY 

PRIDE IS FOREVER”

Original Sound Track 

By 

ADAM EVOLVE

Roof Operations Power point 

Created 

by 

Firefighter Specialist 

Craig Reed

Questions and comments are 

welcome 

Email creed@fire.lacounty.gov

Roof Operations- by Craig Reed.pdf

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