Lessons Learned from the Grenfell Tower Fire

On June 14, 2017, a fire occurred in Grenfell Tower, a London apartment building, that killed 71 people. The fire started at 1:00 a.m. (BST) and within 30 minutes consumed the exterior wall of 20 out of 24 floors. The fire spread over the highly combustible material used to insulate the exterior wall. It then extended through acrylic plastic windows and quickly spread throughout the building, making it impossible for many occupants to escape.

Grenfell Tower

Grenfell Tower was designed in 1967, and construction was completed in 1974. The building was constructed using concrete. It had a flat roof and concrete stairs with plaster-covered walls.1 One side of the building was accessible by roadway; the remaining three sides had gardens at ground level, which were not vehicle accessible. The tower was comprised of 24 floors; 21 floors were residential (129 apartments, six per floor), and the other three floors consisted of office space that had been vacant since 2015. An electric substation was on the first floor. The roof housed an elevator mechanical room, cold-water storage tanks, and an ambulance communication room.

The building was serviced by two elevators, both with firefighter service, and one stairwell that extended from the ground floor to the roof. The stairwell had 30-minute fire rated self-closing doors. The elevators and stairwell were in the core of the building. The boiler room was housed in the basement. Refuse chutes were in a fire rated room near each elevator lobby. (1)

Although the exterior insulation panels, installed during a 2014 renovation, were considered a potential factor in the fire’s burning quickly, many other factors contributed to this unprecedented fire.

Grenfell Tower did not have an automatic fire sprinkler system. The fire alarm system that served the building had smoke detection on each floor in each elevator lobby; however, there were no fire alarm system sounder bases in any residential area. When apartments became vacant, the apartment management company began to install standalone nonsystem smoke detectors with self-contained battery-powered or hardwired devices in each apartment that do not connect to the main fire alarm system and do not alert other occupants of a fire. The apartment management company did not maintain records indicating which apartments had smoke alarms installed. (1) The building had a dry standpipe system serving each floor. An automatic ventilation system activated by fire alarm system smoke detectors was in each elevator lobby.

Soon after the fire, reports surfaced that identified the combustible exterior metal composite material (MCM) panels, a factory manufactured panel consisting of metal skins bonded to both faces of a solid plastic core (foam), as the main contributing factor of the fire.2 Many building owners insulate the exterior building walls to limit outside sound and to reduce heating and cooling costs. These insulating systems include cladding, MCM paneling, foam insulation, and curtain walls. Grenfell Tower used a combination of foam panels and MCM panels.

Figure 1. Grenfell Tower Materials Under Investigation by Police

Figure 1. Grenfell Tower Materials Under Investigation by Police

MCM panels were also attributed as the cause of other fatal fires in the United Kingdom and Dubai. The manufacturer of MCM panels offers two types of panels: noncombustible and combustible. Combustible MCM panels were installed at Grenfell Tower since they were less expensive. (2) The combustible MCM panels were installed over another insulating product, a polyisocyanurate rigid foam, which was attached directly to the exterior wall. The polyisocyanurate rigid foam product had a textured aluminum foil facing, which has a class 0 fire performance rating.3 The MCM panels installed over the polyisocyanurate rigid foam panels created a 50-mm or two-inch gap between the MCM panels and the polyisocyanurate rigid foam panels. Once the MCM panels started to burn, radiant heat was trapped between the MCM panels and the polyisocyanurate rigid foam panels, igniting the polyisocyanurate rigid foam panels. The combined heat release rate of the polyisocyanurate rigid foam and MCM panels was close to the heat release rate of gasoline.4

NFPA Standards and International Building Code

National Fire Protection Association (NFPA) 5000, Building Construction and Safety Code®, and the International Building Code (IBC) have detailed requirements for exterior wall construction and its components. MCM panels, cladding, exterior insulation finishing systems (EIFS), and curtain walls are all part of the nonload bearing exterior wall assembly standards. The IBC requires that exterior covering systems shall not reduce the required fire resistance rating of the exterior wall to which they are attached.

RELATED: Construction Concerns: Responsibility | Are Current Fire Prevention and Education Models Failing Us? | The Grenfell Tower Fire and Fire Safety Materials Testing | The Grenfell Tower Fire: A Closer Look

According to NFPA 5000 and the IBC, depending on the exterior nonload bearing wall assembly material’s fire resistance rating, the size of the building, and the building’s construction type, fire barriers are required.5 These standards are not to be confused with NFPA 285, Standard Fire Testing Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components.6 NFPA 285 is the standard testing method to determine fire propagation characteristics of materials used in nonload bearing combustible wall assemblies. The testing premise is a simulation of a flashover fire in an apartment on a second floor, where the fire extends to the exterior wall covering or to the facade through an open window. NFPA 285 is the testing standard used to determine the propensity of ignition by exposing the exterior wall assembly to radiant heat. The testing method is to simulate an exterior fire to the exterior wall assembly and determine the propensity of ignition. (6)

Standards put in place by the NFPA and the International Code Council (ICC) regarding the installation of MCM panels do not appear to have been followed at Grenfell Tower. There were no fire barriers, and the polyisocyanurate rigid foam panels and MCM panels used were not tested, listed, or rated for the way they were used at Grenfell Tower. (2) Nonload bearing combustible exterior wall assemblies can be safe, provided the exterior wall components are assembled according to the methods and materials used during the fire propagation testing and according to NFPA 5000 and the IBC. (6, 2)

The ignition temperatures for some building materials follow:

• Poly-methyl methacrylate used to manufacture acrylic windows has an ignition temperature of 824° F.7

• Aluminum composite material (ACM) insulation consisting of two thin sheets of aluminum continuously bonded to a polyethylene core has an ignition temperature of 761°F for the polyethylene. (7)

• Glass panes normally break between 550°F and 600°F. (7)

• The polyisocyanurate foam ignition temperature is 798°F. (7)

The NFPA definitions for various building materials include the following:

1. Combustible: a material that, in the form in which it is used and under the conditions anticipated, will ignite and burn; a material that does not meet the definition of noncombustible or limited-combustible. (6)

2. Noncombustible: a material that, in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. (6)

3. Limited combustible: refers to a building construction material that does not comply with the definition of noncombustible material. (6)

NFPA Fire Risk Assessment Tool

What is concerning for many people is what to do if you have a building with exterior foam insulation. Since the tragic Grenfell Tower fire, many enforcement authorities are trying to identify a methodology for examining their inventory of buildings. This has proved to be a very complicated task considering the extensive variables in each high-rise building.

RELATED: Construction Concerns: Combustible Cladding | Interim Report on London High-Rise Fire

The NFPA developed an assessment tool to be used primarily to conduct risk assessments for high-rise buildings with exterior wall assemblies containing combustible components.8 The risk assessment tool will help global authorities with conducting risk assessments. These assessments will help with prioritizing inspections and remediation activities. The risk assessment tool is not intended to provide specific actions to take; it assists in prioritizing the scope of work. The High-rise Building with Combustible Exterior Wall Assemblies Risk Assessment Tool is available on the NFPA Web site. (8)

Figure 2. Generic EIFS System Detail

Figure 2. Generic EIFS System Detail

Exterior Insulation Finishing System

The EIFS is a common type of exterior nonload-bearing wall assembly with combustible components commonly used in the United States. If installed and maintained properly, it is completely safe. Installation of the EIFS can be complex; each layer is dependent on the other to ensure the system will perform according to the NFPA testing and manufacturer’s standards. To ensure the EIFS is installed according to the manufacturer’s methods and materials, a third-party inspector should supervise the plans and installation of the products at the construction site. Not all EIFS have foam or combustible components.

In the hotel industry, the impact of lawn equipment, housekeeping, and luggage carts is a major contributor to EIFS damage. One solution to prevent damage is to install an approved noncombustible stone, tile, or other such similar material in areas to prevent damage where these items will contact the EIFS. Exterior noncombustible material must be approved for use with an EIFS.

The proper maintenance of the EIFS is necessary to ensure that the fire resistant features will not be in jeopardy if the system is damaged. Property engineering teams that maintain buildings with the EIFS must use a contractor certified in EIFS repair and who can provide a warranty.

Additional precautions should be taken to eliminate potential fire hazards as the EIFS ages, such as using only noncombustible landscaping mulch within three feet of an exterior wall constructed using the EIFS. The system should also be inspected after any potential damaging events occur—significant storms, for instance. The Grenfell Tower did not use an EIFS.

Maintaining Exterior Nonload-Bearing Wall Assemblies with Combustible Components

A contractor certified in repairing damage to exterior nonload-bearing wall assemblies containing combustible components must repair these assemblies and provide a warranty for the repair. Properties exposed to significant wind and rain storms should be inspected. The focus should be on the following areas:

• Horizontal joints.

• Sealant joints.

• Penetrations.

• Trim areas where moisture or flame can penetrate.

• Around doors, flower beds, electrical receptacles, exterior lighting connected to the building, other decorative features.

• Where the walls join with roofs at all levels.

• Holes caused by pest infestation.

• Where drainage gutters attach to or penetrate the building.

• Roof termination of the exterior covering.

The following precautions can prevent fires involving exterior nonload-bearing wall assemblies with combustible components:

• Ensure that sprinkler protection is provided in each room.

• Inspect, test, and maintain fire sprinkler systems according to NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, 2017 ed.

• Provide sprinkler protection in porte-cocheres (a passageway through a building or screen wall designed to let vehicles pass from the street to an interior courtyard).

• If balconies are present, prohibit any open flame on balconies (i.e., smoking, pyrotechnics, cooking grills).

• Inspect the building exterior monthly, and have a certified contractor repair any damage immediately.

• No combustible mulch, plants, or vegetation should be within three feet of the base of the building; decorative stone can be used for aesthetic purposes. Smoking areas should be at least 25 feet from a building exterior where there is a combustible exterior.

If these recommendations are followed, buildings with these exterior nonload-bearing wall assemblies should be completely safe to use.

High-Rise Evacuation Plans

Evacuation plans and policies are important for all buildings. In the case of a fire or other emergency, responders follow these policies to get occupants to safety. In most cases, high-rise buildings should be totally evacuated. Preferably, they should be evacuated in phases—not all at the same time. The exits can become overloaded, and the increased stress and panic could lead to injuries and even death. A preferred alternative is to evacuate in phases: Remove occupants from a portion of a building or facility while occupants in other portions of the building carry out normal activity.9 You can accomplish this in a managed phased evacuation of specific floors or areas, removing the more endangered occupants first. (9) If the fire progresses and is not contained, the managed evacuation can continue until the entire building has been evacuated and all occupants are in a safe location.

Most modern fire alarm systems in high-rise buildings in the United States automatically play prerecorded messages that instruct the occupants to evacuate the building. These messages are normally played on the floor of the alarm and the floor above and below the alarm. Some fire departments require that additional floors above and below the alarm floor be evacuated.

It is difficult to believe that a fire of the magnitude of that at Grenfell Tower occurred in modern history. In high-rise operations, firefighters typically do not consider having to contain a fire involving the exterior wall spreading quickly to the remainder of the exterior building. The significant contributing factor to this disastrous fire was the application of insulation on the exterior wall to help with sound protection and reduce heating and cooling costs. If the IBC and NFPA 285 and 5000 were followed, this fire may not have occurred. In the United States, fires involving nonload bearing combustible exterior wall assemblies have occurred with these standards in place. It is imperative to have a third-party inspector monitor the materials and methods in the installation of any exterior nonload-bearing wall assemblies containing combustible components, including MCM panels, cladding, EIFS, and combustible curtain walls.

In buildings using exterior nonload-bearing wall assemblies containing combustible components, building maintenance workers must hire third-party qualified contractors for repairs. As exterior wall assemblies age, they must be inspected to ensure the fire resistive envelope is intact.

Evacuation plans are essential and unique to each facility. An evacuation plan must consider the fire protection features of a building as well as the containment of fire. It is essential to evacuate the most severely threatened group of people first and work toward the less threatened group while maintaining an orderly evacuation. This will reduce the potential of panic and injury. When the fire cannot be contained and is fast moving, an unmanaged total evacuation may be considered, but it is not preferred.

With the common availability of portable gas monitors, responders should conduct air monitoring to ensure no one is exposed to the by-products of combustion. At a minimum, the responders should conduct air monitoring anywhere people are staged in the building involved in fire and the like, including areas of normal business, refuge, treatment, command locations, and firefighters’ staging areas.

The fire at Grenfell Tower, its causes, and the fire prevention standards in place prove that it is essential to make fire and life safety top priorities. The chain of events that led to numerous fire fatalities is proof that continued inspecting, testing, and maintaining fire and life safety systems are critical.

People make decisions according to their training and life experiences. They will naturally try to do the right thing when a decision must be made. These large-scale disasters do not occur from one mistake or one factor but from a chain of events or decisions. Life safety must be the priority; when it becomes secondary or is forgotten, a disastrous chain of events may start without anyone even realizing it.

References

1. C S Stokes and Associates Limited. (2012). Fire Risk Assessment for Grenfell Tower, Grenfell Road. Kensington: C S Stokes and Associates Limited.

2. BBC. (2017, August 4). BBC, London Fire: A visual guide to what happened at Grenfell Tower. Retrieved from BBC: http://www.bbc.com/news/uk-40301289.

3. Celotex Saint-Gobain. (2018, January 22). Celotex Saint-Gobain. Retrieved from Celotex Saint-Gobain: file:///C:/Users/jwgau035/Downloads/rs5000_productdatasheet_aug17-1.pdf.

4. Reed, J. & Clare, S. (2017). Grenfell cladding ‘14 times combustibility limit’.” BBC. Retrieved from http://www.bbc.com/news/uk-40645205.

5. National Fire Protection Association (NFPA) (2015) NFPA 5000, Building Construction and Safety Code®. Quincy, Mass.

6. NFPA. (2012). NFPA 285, Standard Fire Testing Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components.

7. NFPA. (2008). NFPA Fire Protection Handbook, 20th edition (Vol. 20).

8. Lamont, S., & Ingolfsson, S. (2018). High-Rise Buildings with Combustible Exterior Wall Assemblies: Fire Risk Assessment Tool. Quincy: NFPA.

9. NFPA 101. (2015). Life Safety Code.

Jim Gaut is a 37-year veteran of the fire service. He began his firefighting career in 1980 with the Orange County (FL) Fire Rescue Department and worked his way up through the ranks to battalion chief. He was instrumental in designing many training programs, most notably a joint active shooter unified command program with the Orange County Sheriff’s Office. He has taught incident command courses across the United States. He is the senior manager responsible for fire and life safety for Marriott Vacations Worldwide Corporation. He has a bachelor’s degree in fire science. He serves on numerous National Fire Protection Association technical committees including Building Construction and Safety Code®; Standard for Safeguarding Construction, Alteration, and Demolition Operations®; and Standard for Parking Structures®.

No posts to display