Essentials

On most roofing jobs, potential risks are easy to spot. However, spray polyurethane foam (SPF) application hazards often are invisible. Roofing workers who install SPF roof systems must contend with vapors, airborne particles, electric sparks and potential falls—all of which can be prevented by using proper safety equipment and taking certain precautions.

Harmful chemicals

SPF contains two basic chemical ingredients: diisocyanates and polyol resins. Inhaling high concentrations of these chemicals can cause light-headedness, difficulty breathing, headaches, vomiting and unconsciousness and may lead to death by asphyxiation. In addition, polyol resins may be slightly irritating to the skin, and some types of catalysts present in polyol resins can be highly irritating if they contact eyes.

Because of potentially dangerous vapors, a roofing worker must wear an air-purifying or air-supplied respirator while installing an SPF roof system. Air-purifying respirators consist of cartridges or canisters connected to respirators. Air-supplied respirators use external air supplies, such as oxygen tanks. Respirators with full-face pieces provide better protection than those with half-face pieces because they have larger face-to-respirator sealing areas and protect eyes.

In addition to using a respirator, a worker also should wear chemical-resistant gloves, safety goggles, a full-face piece and disposable, protective body suit with a hood. Chemical-resistant boots also are recommended if a worker is handling liquid chemicals.

If working with chemicals, a roofing worker should wash his hands and face before breaks or eating and never leave food or beverages in a work area. If chemicals contact a worker's skin, instruct him to wash with soap and water, not a solvent. If a roofing worker gets chemicals in his eyes, flush his eyes with running water for 15 minutes; if irritation continues, call for medical assistance.

Storage and handling

Proper safety precautions also should be taken before SPF applications begin. Chemicals and coatings should be stored in proper containers away from heat—excessive temperatures can cause pressure buildup that can rupture containers or ignite chemicals. Refer to the applicable material safety data sheets (MSDSs), and tell workers to follow the recommended work practices and procedures.

In addition, SPF equipment should be handled with care. Before each use, a worker should check hoses and couplings for leaks, abrasions or other damage. If any equipment shows signs of wear and tear, replace it.

Other dangers

In the event of a chemical spill, roofing workers should refer to MSDSs for proper procedures. For example, a spill should be contained and absorbed with sand or sawdust. The materials should be disposed of in proper chemical containers and taken to a licensed disposal facility. The area in which the spill occurred then should be washed with water.

Welding and cutting also can be dangerous during SPF applications. Sparks and embers can ignite SPF and start a fire. If welding equipment must be used on an SPF roof, make sure a welding curtain or other safety barrier is in place to help protect SPF and ignitable chemicals.

Electricity poses another potential hazard. Static electricity generated by the flow of liquids and air through an SPF system could ignite flammable solvents. To avoid a fire, make sure all application equipment and flammable material containers on a job site are grounded. Electric equipment used to apply SPF also must be equipped with ground fault circuit interrupters to prevent electric shock if a short circuit occurs in the equipment.

In addition, SPF equipment never should be placed near electric power lines or other sources of electricity. And never plug in or unplug power cords in a spray area when there is a chance of igniting fumes.

As with other installations, the risk of injuries caused by falls on an SPF job always is present—with additional challenges. Polyol resins can be slippery, and air and material supply lines trailing behind a roofing worker applying SPF can cause him to trip. Also, because a roofing worker wears eye protection, a respirator and protective body suit with a hood, his peripheral vision and hearing may be impaired.

Although SPF applications present several unseen hazards, a roofing worker who takes the proper safety precautions can breathe easily.

Peter Greenbaum is NRCA's manager of education programs.