From 1989 to 1996 the Fire Safety Committee of the Concrete and Masonry Industry published a series of reports on fire safety and protection. The series addressed codes and standards and specific types of construction with an emphasis on residential construction, where most fire deaths occur. Most of the information and recommendations remain appropriate today.
Click on title for a PDF of the report.
The need for fire-safe construction in single-family homes, townhouses, and garden apartments is often ignored. There is a steady growth of multifamily, low-rise buildings, such as townhouses with common walls and apartment buildings of three or four floors, which are constructed essentially the same as single-family residences but with many families living under one roof. This multiplies the fire danger. The article discusses protection options that improve life safety and property protection for residential buildings.
Six fundamentals of fire safety in high-rise buildings, as stated by the Fire Safety Committee of the Concrete and Masonry Industry, are described:
- Buildings must remain intact throughout the fire and offer refuge for the occupants until they can be evacuated. There must be no structural failure should there be a burn-out in any portion of the building.
- New building code regulations should be directed towards reducing fire hazards that are not now adequately regulated.
- Compartmentation, smoke control, and early detection constitute a viable basis fire safety.
- Use of combustible structural elements, insulation, and finishes should be carefully restricted and controlled.
- Automatic fire-suppressing systems (sprinklers) should be required.
- Automatic fire-suppressing systems (sprinklers) should be in addition to compartmentation within a story.
Destruction resulting from uncontrolled fires was the primary reason for adopting the first building codes. Because building fires are a major hazard to life and property, building codes require that resistance to fire be considered in building design. Codes provide the means by which structural fire resistance is integrated into the design and construction of the buildings. It is generally presumed that building components will perform satisfactorily for as long as their designated fire ratings indicate under actual fire conditions. However, this is not necessarily true. How are fire ratings determined? Standard laboratory tests provide a means for evaluating the performance of building materials and structural assemblies under fire exposure. Based on the findings from these tests, the fire endurance of the various structural components that make up a building are determined.
The loss of life and property from fire in garden apartments, townhouses, and other low-rise multifamily residences (buildings with up to three floors) can be reduced by upgrading codes and standards governing construction materials and methods.
Townhouses and low-rise multifamily residential buildings contribute heavily to current fire-loss statistics. A very high percentage of these fire losses is attributed to housing facilities constructed under liberal building codes. One way to promote greater fire safety to life and property is to require better fire-resistant construction through the upgrading of building regulations.
Fire tests reveal valuable information about the fire resistance of concrete and masonry. This information has been used to develop and update building code requirements for fire resistance and safety.
Rational design employs this technology to design concrete and masonry structures to withstand the effects of fire. Rational design, or the analytical procedures for determining fire resistance, refers to an engineering method of calculating the duration that a structural element can be subjected to a standard fire test exposure while performing its function, both structurally and as a barrier to heat.
The University of Maryland’s Department of Civil Engineering prepared a revealing report examining fire losses in multifamily residences by construction type. The 1979 report is based on a study to determine whether there is a relationship between construction type and fire losses. Most of the data apply to low-rise construction but some are for fires in mid- and high-rise multifamily buildings. All of the information is valuable in studying low-rise fire protection.
Evidence obtained during the one-year study confirms that concrete and masonry construction in apartment buildings offers the most resistance to fire spread and damage, while unprotected wood frame construction offers the least resistance to fire spread and damage.
If the flame spread and combustibility characteristics of thermal insulation do not significantly contribute to the severity of the fire environment, adding insulation to an assembly will generally reduce the overall heat transmission through the assembly under fire-exposure conditions. This results in lower unexposed surface temperatures. However, this reduction in heat transmission can cause other regions within certain assemblies to develop higher temperatures in comparison with similar assemblies without the added insulation. This may lead to premature structural failure of the assemblies and a subsequent reduction in fire resistance.
People commit arson for various reasons. There are five main groupings for the motives of arsonists: profit, concealment of other crimes, vandalism and malicious mischief, revenge or spite, and pyromania or other mental illness.
As with accidental fires, preventing arson fires is the first line of defense. Local governments, federal agencies, and the insurance industry have undertaken major efforts to set up arson prevention programs. These programs are mostly directed toward preventing arson-for-profit fires.
Arson prevention and protection alternatives based on the type of arson scenario and building occupancy are described. The role of noncombustible fire-resistive construction in the overall protection scheme is presented, along with the recommended action for code-writing bodies to reduce losses due to incendiary or suspicious nature fires. The term arson is used synonymously with fires of incendiary or suspicious nature unless otherwise specified.
Fire, in its uncontrolled state, is one of the great killers of people and the destroyer of economic wealth. Nearly 7,000 people lose their lives in fires each year; thousands more are injured and tens of thousands lose their homes and possessions to its ravages.
In an effort to protect the public from the devastating effects of fire, modern-day building codes have established minimum standards for the protection of life and property. During the last 10 to 15 years, life safety has surfaced as the motivating force behind building code changes. Now, however, there is also a need for emphasis on property protection.
As the fire resistivity of multifamily residences increases, fire losses – measured by extent of flame spread, average dollar loss per fire, and number of injuries per fire – all decrease. As the number of living units in multifamily residences increases, fire losses increase. In residences with more than 20 living units and built of wood-frame construction, injury losses and property losses are significantly greater than in any other combination of construction type and building size.
It was one of the most costly structure fires ever. A large and modern retail distribution centers burned to the ground along with all of its contents. Losses to K-Mart’s 1.1 million-square foot warehouse located near Philadelphia, Pennsylvania, exceeded $110 million. In a little over one hour the huge warehouse and its contents were totally destroyed in spite of the presence of an operating, full-coverage, automatic sprinkler system and quick response by dozens of fire trucks. Only the general offices and computer center survived, separated from the rest of the structure my masonry walls.
Single-family dwellings rank first in the incidence of United States fire losses. In 1981, the U.S. Fire Administration reported that of all structure fires, those in dwellings accounted for 27 percent of all property loss, 50 percent of all injuries, 52 percent of all fires, and 64 percent of all deaths. Indications are that energy conservation efforts may be contributing to the fire problem in single-family homes. Introduction of cellulosic and plastic insulations and greater use of solid fuel and portable heating equipment have increased fire hazards. Contents of single-family dwellings are also changing. There are more electrical appliances and, consequently, more ignition sources. The expanded use of plastics in furnishings not only has added to the fuel load, but has also increased toxicity level of products of combustion.
Innovation and new technologies are emerging in construction methods. The use of noncombustible materials in traditionally all-wood houses is gaining acceptance as new building systems bring down costs. Using noncombustible building materials in a single-family dwelling offers several advantages. One is energy conservation. Concrete and masonry add thermal mass that helps lower fuel bills and reduce required levels of insulation. Passive solar designs that take advantage of this mass effect, as well as earth sheltered housing, are now quite popular. Another advantage is fire safety. Noncombustible materials will not add fuel to a fire nor support combustion in concealed spaces. They do not generate toxic gasses or smoke and will act to confine and limit fire to the area of origin.
As in several years past, fire losses in one- and two-family dwellings again accounted for the highest percentage of fire incidents in the United States. Although the numbers are of substantial magnitude, consider the property damage totals of single-family dwellings compared to the staggering 41.5 billion in estimated damages from California’s Oakland Hills Fire that occurred in October 1991. Almost 2,450 single-family dwellings along with 437 apartments, condos, and other structures were destroyed in that single incident. This one event has brought renewed emphasis on the issue of firesafe single-family construction and may have historical significance in the way single-family residences are designed in the future.
Fire-endurance periods for building components are normally determined by physical tests conducted according to ASTM E119, “Standard Methods of Fire Tests of Building Construction and Materials.” Provisions of the ASTM E119 test require that specimens be subjected to a fire which follows the standard time-temperature curve. Under the E119 standard, the fire endurance of a member or assembly is determined by the time required to reach the first of any specified endpoints. The requirements of the standard are provided and discussed.
ASTM E119 “Standard Methods of Fire Tests of Building Construction and Materials” is the recognized standard in the United States for determining fire-resistance ratings of building members and assemblies. Compliance with fire-resistance ratings specified in each of the model codes is based on testing in accordance with the procedures of ASTM E119.
ASTM E119 contains procedures for determining both structural and barrier fire-endurance end points. In the case of building elements, such as beams and columns, the standard requires the determination of structural fire endurance only since these members are not intended to perform as fire barriers. For bearing walls, floors, and roofs which are required to serve as structural assemblies and may be required to perform as fire barriers. The fire endurance of these assemblies is based only on the first end point reached. Thus a bearing wall, floor, or roof assembly reaching the barrier end point first may still have the capacity to perform structurally for a longer period of time.
There are many situations in buildings where assemblies need perform only one of these two functions. However, an assembly selected by an engineer or architect to meet a structural fire-endurance requirement may have achieved its rating based on fire-barrier performance and possess significantly more structural capacity that is required. This results in the inefficient use of building materials, wasted construction time, and unnecessary construction and manpower costs.
Prospective building owners, building officials, developers, landlords, and tenants should be aware of the advantages of concrete and masonry low-rise multifamily dwellings. There are economic benefits of constructing with concrete and masonry building materials and, a life-cycle cost analysis will show that it is actually less expensive to own such a building than one constructed of wood frame.
Although energy and maintenance savings are also realized in constructing with concrete and masonry, only construction, sprinkler, mortgage, and insurance cost considerations are addressed in this text.
Information on the code requirements germane to concrete and masonry walls is provided.
- Explains the functional requirements of fire walls and describes characteristics common thereto
- Indicates sections of the code that apply to fire walls and their components (parapets, opening protectives, penetration protection and so forth)
- Conceptually examines wall-roof interactions and restraining conditions that are necessary in order for fire walls to meet the code’s stability criterion during a fire.
Information on the code requirements germane to concrete and masonry area separation walls is provided.
- Characteristics common to all area separation walls.
- Fire-rating requirements for area separation walls and their components (parapets, opening protectives, and so forth).
- Orientation of wall configurations that qualify as area separation walls.
Do one-hour fire-rated separations of dwelling units in multifamily housing represent an adequate level of property protection? Model building code requirements for fire resistance of dwelling-unit separations are also examined, along with the methodology used in establishing these requirements. Finally, a balanced design approach to fire safety is proposed for multifamily housing, identifying concrete and masonry construction as the primary component in a system comprised of compartmentation and automatic suppression and detection elements.
An approach for assessing the condition of fire-exposed concrete and masonry building construction is described. Various testing and analytical methodologies are described and some general information is provided about restoration procedures.
Fire limits, also referred to as fire districts or fire zones, were established years ago to protect against large destructive fires (conflagrations) in built-up areas. As the use of fire limits diminished or disappeared altogether, the gap in fire protection was to be filled through the implementation of appropriate building code provisions. An examination of today’s model building codes shows that these replacement provisions have not adequately satisfied this objective. The deficiency lies in the failure of codes to properly address the exterior ignition of buildings due to radiant heat energy or direct flame contact. Recommendations correlating requirements of set-back distances and opening protection for buildings having either combustible exterior walls, or exterior walls with combustible veneers are proposed in this report as corrective action.
Fundamentals of fire safety design for high-rise buildings are discussed.
- The building must retain its structural integrity throughout the duration of a fire, and offer safe areas of refuge for the occupants until they can be evacuated. There must be no structural failure in the event of a burn-out in any portion of the building.
- Horizontal and vertical compartmentation should be utilized to limit the spread of fire beyond the area of origin.
- The use of combustible materials and finish systems (cladding) on exterior walls should be prohibited.
- Active types of fire protection such as automatic detection and alarm systems, and automatic suppression systems are important components of high-rise building design.
- Tradeoffs involving the reduction or elimination of fire resistance or other fire safety features should not be permitted. Redundancy in protection is paramount if the fire safety of high-rise buildings is to improve.
- Protection must be provided to prevent the vertical spread of fire from floor to floor via the building’s exterior openings.
- Code officials must utilize the technological advances available and incorporate changes into the codes based on scientific principles.
An explanation is provided as to why E119 fire tests should be conducted under positive furnace pressure. Evidence is offered that certain types of assemblies tested under negative furnace pressure may not be able to withstand the E119 fire condition for the same duration when tested under positive pressure. This can lead to unconservative conclusions when E119 tests are used as a tool for assessing the adequacy of some fire-rated assemblies in building construction.