Dec 22 2011

Understanding the Importance of Construction Types

Category: BlogBKeyes @ 9:31 pm
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The following article originally appeared in the February 2011 issue of Helathcare Life Safety Compliance 

Construction Types are among the most misunderstood features of life safety in hospitals today. The National Fire Protection Association (NFPA) defines Construction Type as the combustibility and fire resistance rating of the building’s structural elements, such as columns, beams, girders, trusses, arches, joists, floors (and floor assemblies), decks, roofs, and load-bearing walls.

Why is this so important for safety in a hospital? Fire resistance material on structural members of the building provides a certain safety factor. Without fire protection, the extreme heat from a fire may cause the structural members in the building to warp and collapse before the occupants can successfully evacuate the building.

Chapters 18 (for new construction) and 19 (for existing facilities) of the 2000 edition of the NFPA 101 Life Safety Code® (LSC) requires all hospitals to comply with a Construction Type listed in Table 18/19.1.6.2. This table is based on NFPA 220 Standard on Types of Building Construction, and the hospital must comply with the Construction Type listed based on the number of stories and whether the building is protected with automatic sprinklers.

Construction Types are categorized into five different designations:

Type I: All structural members are non-combustible or limited combustible materials. Non-load bearing exterior walls are permitted to be non-rated. Non-combustible materials are obvious, such as concrete, cement block, brick, steel and so forth. Limited combustion materials are those that have a potential heat value that does not exceed 3,500 Btu/lb and either a) has a covering that does not exceed 1/8-inch with a material that has a flame spread rating not exceeding 50, or b) is made of materials that have a flame spread rating that does not exceed 25. Gypsum wall-board is commonly considered to be a limited combustion material, and is permitted to be used in Type I and Type II structural assemblies.

Type II: All structural members are non-combustible or limited combustible materials. This is the same as Type I, however, the difference between the two types is found in the hourly fire resistance rating designation. Type I and Type II construction is commonly found in most hospitals constructed since the 1950s.

Type III: Exterior walls are non-combustible or limited combustible and interior walls and structural members are dimensional wood frame. This type of construction typically has wood floor assemblies and/or a wood rafter roof.

Type IV: Exterior and interior walls are non-combustible or limited combustible and structural members are solid or laminated wood beam. This type of construction typically has heavy timber beams as part of the structural members.

Type V: Exterior and interior walls and all structural members are dimensional wood frame. This is the typical construction found in most homes and light commercial applications.

Each Construction Type found in Table 18/19.1.6.2 of the LSC has a series of three numbers or letters enclosed by parenthesis. These numbers refer to specific fire resistance ratings of certain structural members of the building (see sidebar, page X):

  • § The first number refers to the fire rating of the exterior and interior load bearing walls.
  • § The second number refers to the fire rating of the columns, beams, girders, joists, and trusses.
  • § The third number refers to the fire rating of the floor assembly.

For Type IV construction, the letter “H” holds the second and third spots, indicating there is no fire rating for the heavy timber structural members. Although roof construction is not specified in the table in the LSC, NFPA 220 Table 3-1 does have a fire resistance designation for roof assemblies for each Construction Type, which frequently is less than that for floor assemblies.

Healthcare occupancies are permitted to have different Construction Types in the hospital, provided they meet the requirements for the number of stories and sprinkler protection according to Table 18/19.1.6.2 in the LSC. The LSC does require a two-hour vertical barrier separating different Construction Types, however, unlike occupancy separation barriers in hospitals, which are also two-hour fire rated assemblies, horizontal barriers separating Construction Types are not permitted. This means only vertical barriers separating buildings with different Construction Types are allowed. However, some states and local authorities may have more restrictive requirements for Construction Types so a check with their requirements would be recommended. So, it is very important to know and understand what the Construction Type is in your hospital.

Construction projects are also a problem for those smaller hospitals that were intended to have additional stories added when the need becomes apparent.

“Our challenge came when we wanted to add another story to our building that had unprotected structural steel,” says a facility manager who requested anonymity.

Construction Type II (000) with sprinklers is permitted for a two-story facility, however it is not permitted for a facility with three or more stories.

“If you decide to add another story, then all of the unprotected structural steel on the lower floors need to have fire protection material added,” explains the second facility manager. Fire resistance materials for structural steel come in various forms. For years, hospitals were built with a lath and plaster ceiling assembly in the corridors and rooms that served as a fire rated barrier, thereby providing the required protection for the bare structural steel above the ceiling. Unfortunately, over time, the true purpose of the plastered ceilings was forgotten and sections were removed to add utilities, such as piping and air ducts, and the ceilings were often replaced with a suspended acoustical tile system that did not provide any fire resistance rating. This leaves the bare structural steel without the required fire resistance rating, and compromises the Construction Type.

“Our building over the past 58 years has been built and added onto several times,” says the first facility manager. “I find that I must climb up and around in the entire building envelope to discover what has been put in place.”

Another challenge lies in not knowing exactly what the Construction Type was supposed to be in the first place when the building was originally constructed. Original construction documents may not be available, and current rated wall drawings may be inconclusive. How can you be expected to maintain what you don’t know? This sentiment was offered by yet a third facility manager who also wished to remain anonymous.

“Not possessing accurate life safety drawings that define and designate each Construction Type is one of my greatest challenges. This creates confusion when it comes to understanding what fire safety features we are bound to install and maintain,” he explains.

This appears to be a common problem for many hospitals that is created when the building or addition is first constructed.

“When a new hospital is built, the general contractor provides training for the maintenance staff on the correct maintenance and operation of air handlers, pumps and other mechanical equipment,” says James Murphy, RA, NCARB, president of MRF, Ltd. in Western Springs, IL, and a consultant for The Greeley Company, a division of HCPro, Inc., in Danvers, MA. “But architects rarely provide training to the facility manager on the correct maintenance and operation of the rated wall system.”

Without knowledge in the form of drawings that clearly indicates the different Construction Types and the necessary separation barriers, hospitals are bound to make mistakes that alter the fire resistance rating of the structural support members.

New architects working on additions to the hospital may not be able to understand what the original architect was attempting to do without adequate rated wall drawings.

“Another major challenge is undoing years of maintenance and construction work that was performed without taking Construction Type requirements into consideration,” adds Murphy. “It is apparent that a good deal of time and expense will be spent correcting Construction Type violations that could have been easily avoided if the hospitals had adequate drawings.”

Understanding what your Construction Type is required to be, then analyzing what the conditions currently are keys to LSC compliance.

“Knowing your building Construction Type will make you an asset in LSC compliance while providing a safe environment for your staff and patients,” says Murphy.

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