Providing life safety and property protection is a significant part of a building's design and construction process, and one of the primary focuses of building codes. Many jurisdictions have now adopted a code based on the recent edition of the new International Building Code (IBC).
However, most of the fire safety provisions of the IBC were developed using the least stringent requirements of each of the three previously published model building codes. Building and safety experts are concerned that the current minimum requirements for fire safety – especially for multi-residential structures such as town-houses, dormitories, assisted living facilities, small hotels, etc. – may not provide enough protection for the elderly, college students, disabled persons, and families dwelling in these units.
A movement is underway to increase the level of fire protection in codes by using the balanced design approach to construction. Balanced design considers three fire safety options.
The first component is “containment,” with structural walls, floors, and ceilings of masonry and concrete that provide 2 to 4 hours of protection. The second is “detection,” with smoke detectors to alert residents to evacuate. The final component is “suppression,” using sprinklers to control the fire until the emergency responders arrive on the scene.
Balanced design may suggest that one or two of these components are adequate for some types of buildings. However, for housing the elderly, disabled, students, and families, the building code without all three elements may be insufficient and not provide superior, affordable fire protection.
Each of the three components of balanced design is very important, but works to protect the building and occupants differently. The balanced approach considers both active and passive methods of fire protection.
Detection and suppression systems are active. Detection systems are electrical, hard-wired with a battery backup in the event of a power failure. Most suppression systems (sprinklers) require a water source that may or may not be available in the event of a fire.
Containment with compartmentation is a passive system that does not require any action after construction for activation. Compartmentation with masonry/concrete products, which do not burn and maintain their structural integrity, is a vital part of the equation.
If a fire starts within a given room or area of a building, the non-combustible walls, floor, and ceiling contain the blaze, allowing time for occupants to leave, fire fighters to arrive, or for sprinkler heads to deploy, control, or even extinguish the flames.
Currently, many codes provide for detection and suppression, but do not require non-combustible compartmentation between dwelling units. A significant argument made for not using compartmentation has been the misperception that the use of concrete and masonry would increase the cost of construction so significantly as to make it price prohibitive.
There have been many case studies on initial and life cycle costs showing the advantages of concrete and masonry construction for multi-family dwellings, yet recommendations to improve fire protection in these types of facilities have been denied based on unfounded claims of excessively high costs.
In order to clarify and accurately document the actual cost of building with masonry/concrete products versus wood and steel framing for interior separation walls, floors, and ceilings, a study was commissioned by several groups whose mission is to improve life safety and property protection with non-combustible construction. The New York/New England, Pennsylvania, and Mid-Atlantic Fire Safety Construction Advisory Councils came together to commission the study to show initial costs of balanced design construction. Previous work has been done addressing life cycle costs that emphasized the long-term benefits of masonry/concrete based construction versus wood framing and light gauge steel, but this study specifically addressed initial cost.
With this new study, the industry now has documentation that the cost difference is much lower than perceived by many who are not familiar with concrete and masonry construction for multi-family dwellings. In many cases, the cost differential was 5% or less, and in one instance, initial construction cost with masonry/concrete was less.
The objective of this study was to develop a model to accurately evaluate the relative construction cost of multi-family structures built using a variety of construction materials. The multi-family occupancies modeled were representative of traditional apartment type buildings, condominium style structures, student and elderly housing, and others.
Types of dwellings
The design firm of Haas Architects Engineers, a multi-disciplinary architectural and engineering organization located in State College, Pa., was hired for the project. Haas has a 30-year history of client centered service, including commercial, single and multi-family residential, retail, and sports-based projects.
Two types of four-story multi-family dwellings using various construction types were evaluated for 35 locations around the country. Each model encompassed approximately 25,000 gross sq ft of building area per floor.
The first model was comprised exclusively of single bedroom dwelling units, intended to be representative of student dorms, some types of housing for the elderly, hotels, and motels. The second model was configured using a mix of one and two bedroom dwelling units, intended to be more representative of apartments and condominiums, as well as some types of housing for the elderly. Each building model included the complete fit out, with the exception of movable appliances and furniture. For all cases, the exterior was brick and the building fully sprinklered.
The building construction types, designed using the provisions of the 2003 International Building Code, included:
- Conventional wood framing with wood floor system (Type V-B Construction)
- Conventional wood framing with wood floor system (Type V-A Construction)
- Light gauge steel framing with cast-in-place concrete floor system on metal form deck
- Load-bearing concrete masonry with precast concrete floor system
- Load-bearing concrete masonry with cast-in-place concrete floor system
- Precast concrete walls with precast concrete floor system
- Insulated concrete form walls with precast concrete floor system
- Insulated concrete form walls with cast-in-place concrete floor system
- Insulated concrete form exterior walls with interior bearing walls constructed of concrete masonry units and precast concrete floor system.
Tim E. Knisely, a senior fire and commercial housing inspector for the Centre Region Code Administration, State College, Pa., evaluated the designs for code compliance. Knisely holds a certification as a registered Building Code Official in the Commonwealth of Pennsylvania and more than eight certifications from the International Code Council. Knisely has been involved in fire service for more than 20 years.
Once the design was completed on each of the buildings, Knisely performed a detailed code review, following the requirements of the International Building Code 2003 edition. This review was conducted in accordance with the plan review forms provided by the International Code Council, and was in addition to the review performed internally by the professionals at Haas Architects Engineers.
The report precluded a number of items such as site issues, soil information, etc. that were common to all the buildings and would add identical cost to each project. This decision was verified by Poole Anderson Construction.
Poole Anderson Construction is one of the largest building contractors in central Pennsylvania, with a 75-year history and an annual construction volume exceeding $60 million. To allow for a fair and uniform comparison of the construction costs between trades, the study used accepted prevailing wage rates published for each of the locations. These labor rates were typical for a publicly funded project and allow for a fair labor comparison by eliminating potential cost undercutting by any of the trades.
There were many reasons for selecting the construction type, including initial cost, speed of construction, life cycle cost, insurance, environmental sustainability, structural integrity, natural and man-made disaster resistance, maintenance, and fire protection. All these additional benefits are inherent in concrete and masonry construction.
The final report contained the actual costs for the various building construction types. The study provided the relative cost as a comparison to wood frame as a baseline of 100%, indicating increases or decreases relative to the baseline.
The table shows the relative costs for the 35 cities studied. For more information on these studies, visit www.pafscac.org/additional_cities.htm.
Based on the cost estimates prepared by Poole Anderson Construction, the increased expense for using non-combustible masonry/concrete construction materials versus traditional wood framing or light gauge steel was minimal (-3% to 5%). Comparatively speaking, this amount is less than the contingency budget typically recommended to the owner for unanticipated expenditures during the project.
The minimal increase in construction cost will pay for itself over the life of the structure. Materials like concrete masonry, precast concrete, and cast-in-place concrete have many other advantages beyond their inherent fire performance, including resistance to mold growth, energy efficiency, resistance to damage by vandalism, and minimal damage caused by water and fire in the event of a fire in the building.
Summaries of the detailed report are available from the Fire Safety Construction Advisory Councils (FSCAC). For more information about the organization, call 866-SAFE-NC3 or visitwww.firesafeconstruction.org,www.pafscac.org.
Steve Szoke is Director of Codes and Standards for the Portland Cement Association, Skokie, Ill. He previously worked for the Brick Institute of America, National Concrete Masonry Association, and the Southeast Cement Promotion Association.