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Roofing Construction Flammability and Toxicity Hazards


April 04, 2017


Abstract: Roofing trade chemical products expose workers to significant safety and health hazards on the job.

Single-ply roofing, a sub-specialty category, routinely uses highly-flammable and toxic materials (adhesives and solvents) during installation. Depending upon use, these products have the potential to expose workers to dangerous levels of toxic vapor, fire and explosion during handling.

In order to reduce energy costs in roofing, contractors install cool roofs (1) known as single-ply roofing.

As outlined by Bob Craig in EDC Magazine, "The majority of new roofing is a white single-ply membrane, either TPO (thermoplastic polyolefin) or PVC (polyvinyl chloride). This is due mostly to new energy codes that require reflective roofing to reduce heat absorption into the structure.”

An unanticipated consequence of single-ply construction requires workers to handle highly flammable solvents and adhesives to secure roofing materials (membrane) in-place.

Historically, asphaltic tar (bitumen) heated by propane kettles was mixed into roofing gravel as a sealing agent.

Today, single-ply roofing construction involves high-tech flexible membrane, secured in place with adhesives and fasteners.

As some adhesives and solvents contain extremely flammable properties, depending upon use, contain the potential to severely impact workers’ safety and health.

In addition to the flammability factor, workers may be exposed to toxic vapor intrusion, creating adverse health effects.

To control toxic vapor from entering a worker’s breathing zone, ventilation strategies (engineering) should be considered to reduce hazardous effects.

In addition, proactive safety instruction, personal protective equipment (PPE) and workplace vigilance (buddy system) are recommended safety practices to insulate and protect workers from hazards of chemical products.

1 According the EPA, cool roof projects constitute 25 percent of commercial roofing; per cool roof requirements in California.

ADR Safety Program

In an effort to improve safety and lower insurance cost, a consortium of roofing contractors established an alternative dispute resolution (ADR) safety program. They designated an independent safety inspector to annually monitor contactor worksites.

Since responsibility and accountability had not clearly defined, safety-violations by the member-contractors, warning notices and advisories went unheeded.

Single-Ply Roofing Project

While upgrading a school gymnasium roof, a roofer began installing rolls of flexible roofing membrane, adhering the materials in place with a heat gun and adhesives.

He used a damp cloth soaked in Xylene, a highly-flammable solvent, to wipe down each newly installed patch.

After several hours of work, he became drowsy from the vapor. In order to obtain more materials, he climbed down a ladder to his truck, and lost consciousness, falling directly to a concrete slab 25 feet below.

He sustained serious injury, requiring months of physical rehab and loss of earnings.

The ensuing injury investigation determined the roofing contractor provided common albeit, highly-flammable and toxic products to his workers.

Use of the adhesives and solvent created an unexpected consequence of intoxication by vapor, resulting in a fall from elevation.

It was revealed the employee never received chemical specific training, respiratory protection, or personal protective equipment (PPE) by his employer.

The company sustained considerable financial loss, multiple serious regulatory citations, which resulted in higher operating costs and insurance.

Roofing Apprenticeship Center

During a recent onsite safety inspection of a new roofing apprenticeship training center, multiple commercial chemical products were identified within the facility including flammable materials and toxic substances.

In addition, a number of unlabeled, open containers of chemical products were identified in vulnerable areas.

Cylinders of pressurized flammable gas (LPG) were placed on open shelving or in boxes adjacent to student training areas.

It was also determined that mandatory OSHA safety programs had not been addressed: hazard communication, safety data sheets (SDS), fire protection, and emergency action plans (EAP).

Final safety recommendations prompted installation of new flammable storage cabinets, fire protection equipment, OSHA danger and caution signage, and an update to mandatory written programs.

Criticality of Handling Flammable Solvents and Adhesives

As Michael Polkabla, Certified Industrial Hygienist explains, “To protect workers who use and handle flammable solvents or adhesives on the jobsite, we must always remember that beyond the obvious hazards of fire and explosion, there are other factors that directly influence worker health and safety. Virtually all flammable solvents that are used in construction can also cause physical harm through the breathing of vapors, through contact with skin, through accidental ingestion, and even injection into the skin. Inhalation of solvent (adhesives) vapors occurs mainly through use of such products with limited ventilation, however even on a rooftop, such exposures may be at harmful levels. That is why it is important to know the hazards of the solvents and materials you are working with (for example, refer to the SDS) and to take the appropriate precautions such as use of a respirator, using adequate ventilation, working upwind, etc.”

Xylene Exposure

According to the California Department of Health Services (DHS), “Xylene enters your body rapidly when you breathe in its vapors. It can also be absorbed through your skin, particularly if the period of contact is lengthy.

Overexposure to xylene most commonly affects your nervous system, respiratory system, and skin.”

Recommendations for safety engineering, protection and substitution are as follows:

Engineering Controls: Whenever possible, employers must use engineering and administrative controls rather than personal protective equipment to prevent overexposure. Engineering control methods include installing ventilation, changing the work process, and changing work practices. Containers should be tightly covered to prevent evaporation. Exhaust ventilation systems capture contaminated air at its source before it spreads into the air in your breathing zone.

Personal Protective Equipment: When engineering controls cannot sufficiently reduce exposures, a respirator must be worn and a respiratory protection program must be developed by the employer, per Cal/OSHA regulations (GISO 5144).

When frequent or prolonged skin contact with xylene is unavoidable or if splashing may occur, other protective equipment such as gloves or face shields must be worn.

Protective clothing should be made of a material resistant to xylene, such as polyvinyl alcohol (PVA).

Even the most resistant materials will be penetrated quickly and should be replaced often.

Substitution: The most effective way to reduce hazardous exposure to xylene is to substitute a safer chemical product for more toxic ones.

However, the health and safety hazards of the substitute must also be carefully considered to ensure that it is actually safer.

Roofing Safety Expert Witness

Testifying experts serving roofing construction injury cases need to be experienced, and knowledgeable about the roofing construction industry and especially the hazards of the trade.

Experts fluent in specialty-trade practices, safety inspection, and chemical based “trade products” afford considerable value to their clients.

In addition, familiarity with trade tools, materials, personal protective equipment (PPE), fall protection, and specific OSHA regulations is the domain of a roofing expert.

A safety expert’s mission is to assist the trier of fact understand complex trade and safety concepts, specific to an injury or illness case.


Roofing industry professionals can reduce injury and illness and better protect workers by identifying site specific hazards including production chemical products onsite.

By implementing proactive chemical safety procedures in the planning stage, adequate measures can be implemented to target and control hazards and exposure.

When contractors employ safe engineering practices and insure proper training and personal protective equipment (PPE) is provided, workers can safely accomplish their work.

In addition, roofing contractors are required to conduct reasonable and appropriate workplace safety inspections including timely follow-up and correction.

At the conclusion of a roofing safety inspection, rather than archiving the reports, management can share the details with their employees.

Using the information and recommendations from onsite safety audits during tailgate-toolbox training, workplace injury and illness can be effectively controlled.


Craig, B., “White Single Ply Roofing Membrane? Not so Fast!” 2014, EDC Magazine ply%20roofing%20membrane_%20not%20so%20fast!%20_%20ed%20c%20magazine.pdf

Emergency Action Plans (Federal OSHA) 29 CFR 1910.38

Emergency Action Plan (California) CCR, Title 8, §3220

Hazard Communication Standard (HCS) OSHA 29 CFR 1910.1200

Roofing Construction Toxicity and Flammability Hazards

Hazard Communication Standard,(California) CCR, Title 8, §5194

O’Connell, D., Polkabla, M., Garcia, A., “Controlling Xylene Exposure,” (2010), Bilingual Roofing Inspection Summary, SAFETRAN, LLC.

“Using Cool Roofs to Reduce Heat Islands,” US Environmental Protection Agency (EPA)

Xylene Fact Sheet, California Department of Health Services (1989), Hazard Evaluation System and Information Service,

Xylol, (Xylene Solvent), courtesy of W.M. Barr, Memphis, TN.

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