Essentials

Spray polyurethane foam (SPF) roof systems are unique and expose SPF applicators to a variety of dangers during the SPF application process, as well as some that are confronted by all roofing workers. If SPF applicators follow precautionary work practices, the hazards of SPF roof system applications can be reduced or eliminated.

Chemical risks

A dual-component formulation is the basis for SPF roof systems. One part is an isocyanate, and the other part is a polyol resin. The components are transferred from their individual containers into a proportioning unit that pumps proper amounts of each through a hose to a spray gun where they are mixed and applied to a surface.

Components used in SPF roofing applications and certain top-coat products usually are characterized by the U.S. Department of Transportation as Class 3 hazardous materials because of their flammable and toxic natures. Breathing isocyanate vapors, especially when concentrations are increased during spray applications, can cause the following symptoms:

• Irritation of the eyes, nose or mouth
• Headache
• Tightness in the chest or difficulty breathing
• Dryness of the mouth or throat

Isocyanate contact with the eyes can cause permanent damage, and breathing vapors can lead to death. Polyol resins, blowing agents, catalysts and top-coat products used with SPF roof systems also may pose significant health risks when they are inhaled, ingested, or contact the skin or mucous membranes.

In light of these dangers, using personal protective equipment is essential for roofing workers involved with SPF applications. That includes using air-purifying respirators designed to filter organic vapors through a cartridge or canister or atmosphere-supplying respirators that deliver air from a source other than the ambient atmosphere. Full-face respirators incorporating an eye shield into a face-sealing respirator are the most effective protection against inhalation and overspray of SPF. Respirator selection depends on the concentrations of SPF in the ambient atmosphere; the Occupational Safety and Health Administration and National Institute for Occupational Safety and Health provide respirator guidelines.

Roofing workers should be supplied with proper respirators and must be trained about respirator fit, operation and maintenance.

To avoid skin contact with chemicals associated with SPF components, workers also must wear safety goggles (if full-face respirators are not used), disposable protective body suits or coveralls with hoods or head coverings, chemical-resistant shoes or boots, and gloves.

Equipment for spray applications may pose a hazard for entry of materials into a worker’s skin. Pressurized materials from a spray gun can enter the skin and cause serious health consequences. Workers should wear gloves with sufficient composition and strength to minimize such a risk while keeping their hands free of spray residue. A spray head never should be held close to the body when a unit is pressurized.

First aid

Manufacturers or distributors of SPF components are required to supply material safety data sheets (MSDSs) for their materials. These MSDSs describe a material’s hazardous nature or toxicity and symptoms that may result from material exposure, inhalation or ingestion. An MSDS also provides information about emergency first-aid treatment required when an incident or injury occurs.

General first-aid procedures instruct a roofing worker who gets SPF on his skin to wash the area with soap and water and remove any clothing SPF has permeated. If irritation or dermatitis results, the worker should seek medical attention. SPF contact with the eyes requires an immediate flushing with sterile water or clean, cool tap water for at least 15 minutes and medical attention. If a roofing worker is coughing or experiences difficulty breathing, he should be taken to an area with fresh air and a doctor should be called.

SPF roofing applications require specialized equipment, materials and work practices. Equally important is attention to unique safety issues to ensure safe, injury-free SPF job sites.

Harry Dietz is NRCA’s director of risk management.