Building Classifications and Structural Fire Resistance

Comprehensive review flashcards covering Chapter 2: Building Classifications, Construction Types I-V, Fire Resistance Standards (ASTM E119, ASTM E136), Occupancy Classifications (IBC & NFPA), and Fire/Fuel Loads.

In building construction terminology, what is the difference between 'structural components' and a 'member'?

'Structural components' refers to a wide pool of diverse structural elements that work together to maintain structural integrity (such as supports, fasteners, and reinforcing materials). A 'member' refers generically to a specific type of component that serves a defined purpose across varying materials and designs (such as a wooden or metal beam).

What are the five major building construction types classified by building codes?

1. Type I — Fire-resistive
2. Type II — Noncombustible or protected noncombustible
3. Type III — Ordinary
4. Type IV — Mass timber
5. Type V — Wood frame

Why is 'lightweight' not included as an independent construction type in Table 2.1?

Lightweight is not a construction type; rather, it forms components of other construction types.

In the 3-digit fire resistance rating code specified by the IBC and NFPA 5000 (such as Type I 4-4-2), what does each digit represent?

The digits represent rated hours of fire resistance for specific structural components in order: • First digit: Fire resistance rating of exterior bearing walls • Second digit: Fire resistance rating of structural frames or columns and girders supporting loads of more than one floor • Third digit: Fire resistance rating of the floor construction

How does a single lower-rated element affect the overall building construction classification of a structure?

Overall building construction type is determined by the lowest-rated building construction element. A single element can downgrade the classification, such as the addition of a single wood element in an otherwise noncombustible building.

What tactical hazards do dropped ceilings present to firefighters during structure fires?

Dropped ceilings create concealed spaces (similar to attics or pipe chases) where fires can burn undetected and travel to other areas. They often lack sprinklers or proper draft stopping, contain combustible wiring, cause water deflection from suppression streams, and pose a severe collapse hazard.

What critical factors contributed to the loss of nine firefighters in the June 18, 2007 Charleston Sofa Super Store Fire?

Fire burned undetected above the showroom inside a dropped ceiling void where combustible smoke and gases accumulated. When windows were broken to ventilate and search, the entrainment of air fed the fire, creating rapidly untenable conditions that disoriented and trapped firefighters.

What defines Type I (fire-resistive) construction, and what common structural materials are utilized?

Type I construction is classified by noncombustible or limited-combustible structural components having specified fire resistance ratings. It is most commonly constructed using reinforced concrete or protected steel frames (as unprotected steel has no inherent fire resistance).

What combustible materials are permitted by model building codes in Type I construction?

Permitted combustible materials include fire-retardant-treated wood (FRTW) in roofs or interior partitions, roof coverings, interior wall and floor finishes/trims, window sashes and frames, doors and door frames, nailing and furring strips, platforms, light-transmitting plastics, and restricted foam plastics.

What is the fire resistance requirement for structural components in protected noncombustible (Type II) construction?

Structural components must have a minimum of a $1\text{-hour}$ fire resistance rating.

Under what condition do some building codes permit omitting the fire-resistive rating for roof construction in Type II buildings?

When the roof is located more than $20\text{ feet}$ ($6.1\text{ m}$) above the floor.

What three factors determine the speed at which unprotected steel members fail under fire conditions?

1. Ceiling height of the building
2. Size of the unprotected steel members
3. Intensity and duration of the exposing fire

What structural assemblies characterize Type III (ordinary) construction?

Exterior walls are constructed of noncombustible materials (such as masonry, concrete block, concrete slab, or stone), while interior structural components (walls, columns, beams, floors, and roofs) are permitted to be partially or wholly combustible.

How do the IBC and NFPA designate the protected and unprotected subclassifications of Type III construction?

• IBC: Protected is Type III-A; unprotected is Type III-B • NFPA: Protected is Type III (211); unprotected is Type III (200)

What collapse hazard occurs in Type III construction when interior combustible structural components fail?

When interior wood members burn through and lose load-bearing capacity, the exterior masonry walls lose their lateral support and can collapse outward.

What are 'taxpayers,' and what specific collapse hazards are common in legacy Type III construction?

Taxpayers are classic multistory brick Type III buildings constructed from the late 1800s to the mid-1900s. Common collapse hazards include fire cuts made in floor/ceiling beams and girders, and unsupported ornamental parapet walls.

What dimensional and concealed space requirements define Type IV (mass timber / Heavy Timber) construction?

All structural timber elements must adhere to minimum dimension sizing greater than $4\text{ inches}$ ($100\text{ mm}$) on all sides. Interior solid or laminated wood elements, floors, and roofs generally must have no void or concealed spaces.

What are the four subclassifications of Type IV construction recognized by the International Building Code (IBC)?

Type IV-A, Type IV-B, Type IV-C, and Type IV-HT (based on required fire resistance ratings and timber element dimensions, including cross-laminated timber).

What is the primary fire hazard associated with Type IV (mass timber) construction?

The relatively large amount of fuel contained within the structural supports, alongside potential industrial residues or oils embedded from prior occupancy uses.

What defines Type V (wood frame) construction, and when was light-frame construction introduced in the United States?

In Type V construction, all primary structural components (bearing/nonbearing walls, floors, roofs, beams, columns, partitions) may be composed of wood or other combustible materials. Light-frame construction was introduced in the United States in the 1830s.

What is the fundamental fire spread problem inherent to Type V construction?

The presence of extensive combustible concealed voids between wall studs and floor joists, which provide open channels for fire to travel throughout the entire structure.

What is mixed construction, and what operational challenge does it pose for firefighters?

Mixed construction occurs when a new structure is added to an existing structure of a different construction type. A major challenge is that the combined structure may exceed the height or area restrictions established for one of the construction types present.

Which five material properties directly influence the fire resistance of a structural assembly?

1. Combustibility
2. Chemical composition
3. Thermal conductivity
4. Density
5. Dimension

How do fire resistance ratings differ from fire protection ratings, and which NFPA standards govern doors and windows?

Fire resistance ratings evaluate the time a structural assembly maintains its load-bearing capacity and acts as a barrier under fire conditions. Fire protection ratings measure how well opening protective assemblies (doors and windows) withstand fire based on NFPA 252 (door assemblies) and NFPA 257 (window and glass block assemblies).

Which two standardized fire resistance test methods are universally accepted by model building codes?

ASTM E119 (Standard Test Methods for Fire Tests of Building Construction and Materials) and ANSI/UL 263 (Standard for Fire Tests of Building Construction and Materials).

What critical fire behavior information does the ASTM E119 test fail to evaluate?

ASTM E119 does not provide: • Assembly performance constructed with untested lengths or components • Evaluation of smoke, toxic gases, or combustion products generated • Measurement of the passage of smoke or combustion gases • Fire behavior of structural joints (floor-to-wall or wall-to-wall) • Flame spread measurements over surfaces • Effects of unsealed penetrations (electrical outlets, plumbing) unless specifically incorporated into the test assembly

What are the required furnace temperatures on the ASTM E119 standard time-temperature curve at $5\text{ minutes}$, $1\text{ hour}$, and $4\text{ hours}$?

• At $5\text{ min}$: $1{,}000^\circ\text{F}$ ($538^\circ\text{C}$) • At $1\text{ hr}$: $1{,}700^\circ\text{F}$ ($927^\circ\text{C}$) • At $4\text{ hrs}$: $2{,}000^\circ\text{F}$ ($1{,}093^\circ\text{C}$)

What conditions cause an assembly to fail the first protocol of the ASTM E119 test?

A specimen fails if:

1. It is breached, allowing hot gases to ignite a dry cotton pad placed $1\text{ inch}$ ($25\text{ mm}$) from the unexposed surface for $30\text{ seconds}$.
2. Heat transmission causes the unexposed surface temperature to increase by more than $250^\circ\text{F}$ ($121^\circ\text{C}$).

What are the test parameters for the hose stream test in the second ASTM E119 protocol?

The second specimen is exposed to fire for half the test duration (maximum $1\text{ hour}$), then hit with a smooth bore nozzle at a nozzle pressure of $30\text{ psi}$ ($207\text{ kPa}$) from a distance of $20\text{ feet}$ ($6\text{ m}$). Water must not penetrate through or past the assembly.

According to Table 2.2, what are the primary hazards associated with Residential (Type V) and Industrial (Type I / Type II) occupancies?

• Residential (Type V): Fire loading, truss construction, renovations, rapid extension in voids • Industrial (Type I / Type II): Hazardous materials, difficult to ventilate

What are the 10 major occupancy classifications established by the International Building Code (IBC)?

1. Assembly — Group A
2. Business — Group B
3. Educational — Group E
4. Factory and Industrial — Group F
5. High Hazard — Group H
6. Institutional — Group I
7. Mercantile — Group M
8. Residential — Group R
9. Storage — Group S
10. Utility and Miscellaneous — Group U

What dwelling types are governed by the International Residential Code (IRC) rather than the IBC?

One- and two-family dwellings (including single-family homes, duplexes, and townhouses) that are less than three stories above the grade plane.

How many major occupancy classifications are recognized by the NFPA, and which standard outlines them?

The NFPA recognizes 12 major occupancy classifications, outlined consistently with NFPA 101 Life Safety Code and NFPA 5000.

What two design approaches are permitted for mixed-use occupancies in building codes?

1. Separated mixed-use: Different occupancy types are separated by rated fire barriers (typically ranging from $1$ to $3\text{ hours}$).
2. Nonseparated mixed-use: The entire building is designed to meet the code requirements of the most restrictive occupancy classification present.

What code violation led to 36 fatalities in the December 2, 2016 Ghost Ship fire in Oakland, California?

The building was approved as a warehouse occupancy but had undergone an illegal change of use and occupancy without permits into residential, artist studio, and assembly spaces with noncompliant egress and electrical violations.

How are 'fuel load' and 'fire load' defined, and how is fire load calculated?

• Fuel load: The total quantity of combustible material in a compartment (structural framing, trim, contents). • Fire load: The maximum amount of heat released if all fuel is consumed; calculated as the weight of combustibles multiplied by their heat of combustion, expressed in $\text{lb/ft}^2$ ($\text{kg/m}^2$) or total energy in megajoules ($\text{MJ}$).

Which standardized laboratory test is most commonly used to differentiate between combustible and noncombustible materials?

ASTM E136, Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at $750^\circ\text{C}$.

What is Heat Release Rate (HRR), and in what units is it typically measured?

HRR is the power of the fire, measuring the amount of heat released when a material burns over time. It is measured in Watts ($\text{W}$), Joules per second ($\text{J/s}$), kilowatts/megawatts ($\text{kW}$ / $\text{MW}$), or British Thermal Units ($\text{Btu}$).

What are 'fire stops' according to building construction terminology?

Solid materials (such as wood blocks) installed in hollow walls, floors, false ceilings, penetrations, cocklofts, or crawl spaces to prevent or limit the vertical and horizontal spread of fire and products of combustion.