Interior Finishes
. Author(s): James Lathrop. Published on July 1, 2014.

It has long been recognized in the fire protection community that interior finishes can present serious fire safety issues. Interior finishes have been a major contributor to loss of life in a number of significant assembly occupancy fires, from the 1942 Cocoanut Grove fire in Boston, Massachusetts (492 fatalities), to the 1977 Beverly Hills Supper Club Fire in Southgate, Kentucky (165 fatalities), to the 2003 Station nightclub fire in West Warwick, Rhode Island (100 fatalities), to last year’s Boate Kiss nightclub fire in Santa Maria, Brazil (more than 240 fatalities). Recent fires at the Kiss nightclub and elsewhere demonstrate that this is not just an historical issue but a continuing one.

Almost a century ago, interior finish items such as cellulosic paneling (wood, pressboard, fiberboard) and cellulosic ceiling tiles—those one-foot-square ceiling tiles that were typically glued to existing plaster ceilings and, if still in place today, can create combustible concealed spaces above suspended mineral tile ceilings—were frequently cited in articles and reports about fires. In the 1960s, cellular or foamed plastic became a hot topic for interior finishes. The combustibility of these materials became such an issue that the federal government became involved, and the plastics industry eventually signed a consent decree with the Federal Trade Commission regarding its promotion of such products. The Station and Kiss fires reminded us that cellular or foamed plastic products are still being used improperly and that they can contribute to fire events resulting in large numbers of fatalities.

Meanwhile, other potentially problematic materials have emerged and are widely used in a variety of buildings, including assembly occupancies. New products such as polypropylene (PP) and high-density polyethylene (HDPE) are becoming increasingly popular, but if untreated they can present serious fire challenges. The codes address these emerging issues, but proper enforcement will only occur when people are aware of the threat and of the requirements designed to address it, and if jurisdictions are using the most up-to-date editions of the codes.

Testing evolution

NFPA has three primary documents that address interior finishes, including NFPA 101®, Life Safety Code®, NFPA 1, Fire Code, and NFPA 5000®, Building Construction and Safety Code®. The interior finish requirements in NFPA 1 are extracted from NFPA 101, and the NFPA 5000 provisions are the same as the NFPA 101 provisions for new construction, so it makes sense to focus on NFPA 101. Although the International Building Code (IBC) and the International Fire Code (IFC) of the International Code Council (ICC) approach the subject differently, the requirements end up being similar and, in many cases, identical. The current editions of these codes all address interior finish issues, and include new requirements for PP and HDPE.

Old Test, New Test
Why NFPA 286 testing is preferred for plastics that melt and drip

All the major model codes in the U.S. now require that interior finishes using polypropylene (PP) or high-
density polyethylene (HDPE) be tested in accordance with NFPA 286, Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth. This full-scale test is better at determining the hazard of an interior finish—especially with certain plastics that can drip or melt and fall to the floor—than its predecessor, ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, also known as the “tunnel test.”

Read more about NFPA 286 testing.

Interior finishes are defined in NFPA 101 as the exposed surfaces of walls, ceilings, and floors within buildings. (Floors are not part of this discussion, however; they’ve had their own regulation since 1981 and are not subject to the testing conducted on wall and ceiling finishes.) Interior wall and ceiling finishes are defined as fixed or movable walls and partitions, paneling, wall pads, and crash pads applied structurally or for decoration, acoustical correction, surface insulation, or other purposes. Combustible lockers other than those made of wood are also treated as interior finishes. The annex of NFPA 101 clarifies that washroom water-closet partitions are to be treated as an interior finish.

Pooling liquid on the floor continues to burn

The arrangement of a test to evaluate untreated, non-fire-rated high-density polyethylene without aluminum heat sink panels, with the panels constructed as a bathroom stall. As the material burns, it melts and drips, with the pooling liquid on the floor continuing to burn.
PHOTO: James K. Lathrop

NFPA 101 has regulated interior finishes since the 1920s, when it was known as the Building Exits Code, and has addressed the specific problems of cellular or foamed plastics since 1976. Exposed cellular or foamed plastics have played a role in a number of major fires in a variety of occupancies, including nightclubs and other assembly occupancies. Because of the potential combustibility of cellular or foamed plastics, the code includes stringent requirements when those materials are left exposed as interior finishes.

According to NFPA 101, the only option is to evaluate these products in large-scale tests that measure both combustibility and smoke release characteristics for the use intended under actual fire conditions. The test must be conducted on the finished foamed plastic assembly related to the actual end-use configuration. One means of evaluation is the test described in NFPA 286, Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth. Tests developed by Underwriters Laboratories and FM Global are also acceptable. If a test does not evaluate smoke release, the material would have to be additionally tested per NFPA 286 to obtain the necessary smoke release data.

Recently, NFPA codes have determined that PP and HDPE require special consideration when used as interior finishes. Bathroom partitions, school and work lockers, and what are known as demising walls—shared walls such as those between use spaces to separate different activities, for example—are common examples of products or building elements that might be constructed of such materials. Both the NFPA and the ICC codes have been revised to clarify that such products are considered interior finish.

Both PP and HDPE are types of plastics, and if untreated and exposed to fire, they can burn, melt, and drip, resulting in what could be described as a flammable liquid fire on the floor. The fire gives off not only significant heat but copious smoke. Recent room-corner tests demonstrate that untreated HDPE partitions can drive a room to flashover in under 10 minutes. Although this could be considered slow compared to some products, the resulting fire, which mimics a flammable liquid fire, as well as heat and smoke production, demonstrate a significant problem. Some manufacturers add fire retardants during the manufacturing process to reduce the fire hazard of these materials.

The traditional “tunnel test” used on all interior finishes (ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials) evaluates materials without consideration of whether they’re intended for walls, ceilings, or floors—all materials are tested on the ceiling of the tunnel. The conclusion was that the nature of PP and HDPE was such that ASTM E84 testing was inappropriate and that the testing described in NFPA 286 is the proper way to regulate them. (See “Old Test, New Test,” facing page.) This is similar to what happened with foamed plastics in the 1960s, when it was determined that the tunnel test was inappropriate for a specific product and that full-scale testing should be conducted.

All the major model codes in the United States now require that interior finishes using PP or HDPE be tested in accordance with NFPA 286. This full-scale test is far better at determining the hazard of an interior finish, especially with certain plastics that can drip or melt and fall to the floor. Chapter 10 of the 2012 edition of NFPA 101 states that PP and HDPE materials cannnot be used as interior wall or ceiling finishes unless they are tested in accordance with NFPA 286 and that the tests must be peformed on a finished assembly with the maximum thickness intended for use.

The pass-fail criteria for a product using NFPA 286 are not contained in the test method standard, a practice that is becoming more common for both NFPA and ASTM test methods. The accepted practice is to leave the pass-fail criteria to the various building, fire, and life safety codes. The pass-fail criteria in NFPA 101, for example, state that during the 40-kilowatt exposure (the first five minutes), flames shall not spread to the ceiling; and during the 160-kilowatt exposure (the next 10 minutes), the flame shall not spread to the outer extremity of the sample on any wall or ceiling; flashover, as described in NFPA 286, shall not occur; the peak heat release rate throughout the test shall not exceed 800 kilowatts; and for new installations, limitations exist for the total amount of smoke that can be released throughout the test.

Even though many jurisdictions reference older editions of model codes and standards, PP and HDPE should be tested in accordance with NFPA 286 and meet the pass-fail criteria of the most recent editions of the model codes. Any architect, interior designer, specifier, or contractor planning to use PP or HDPE as an interior finish should request test reports from an accredited independent laboratory showing that the material meets these requirements.

James K. Lathrop is vice-president of Koffel Associates, Inc., and a former chief life safety engineer at NFPA.

In This Section
  • Old Test New Test Why NFPA 286 testing is preferred for plastics that melt and drip