Fire Safety
A construction worker is shown using a portable fire extinguisher to extinguish a small fire.
Date Posted: 05/31/2024
On average, between 2016 and 2020, firefighters responded to more than 11 fires a day at buildings under construction in the U.S. Those fires led to an annual average of five civilian deaths, 62 civilian injuries, and over $376 million in direct property damages.
Construction site fires create a significant risk of property damage, personal injury, and even death. Structures with wood framing are particularly susceptible to fires. Although steel-frame buildings are just as vulnerable to fire risk, wood-framed facilities are more likely to collapse when on fire. Construction site fires often happen before sprinkler systems and alarms have been installed so that fires can spread with little warning. Since there are reserves of combustible materials, a stray spark or smoldering debris can lead to a large disaster.
How do Fires Start?
Fire is a chemical reaction that requires three elements to be present for the reaction to take place and continue. The three elements are:
Heat or an ignition source
Fuel
Oxygen
These three elements are typically referred to as the “fire triangle.” Fire results from the chemical reaction between the fuel and oxygen in the air. Heat, fuel, and oxygen must combine precisely for a fire to start and continue to burn. If one element of the fire triangle is not present or removed, fire will not start or, if already burning, will extinguish. Ignition sources can include any material, equipment, or operation that emits a spark or flame, including apparent items, such as torches, and less obvious items, such as static electricity and grinding operations.
Common Sources of Construction Fires
Hot work: Hot work operations pose a significant risk because they can introduce ignition sources into many worksite areas. Even several hours after welding, soldering, grinding, or other hot work has been completed, a spark can smolder and ignite combustibles, sometimes after crews have left for the evening. Implementing a hot work permit system and observing a dedicated fire watch can help address the risk of fires from hot work operations.
Use of temporary heaters: All temporary heaters should be UL-listed and used in accordance with the manufacturer’s instructions. Maintain safe distances from combustible materials and prohibit other contractors and workers from bringing temporary heaters onto job sites without approval. Contractors should monitor heaters for safe operation during use.
Smoking: Smoking must be prohibited at or near operations that constitute a fire hazard and must be conspicuously posted: "No smoking or open flame." Improperly extinguished cigarettes can endanger construction site personnel or property. A construction site should be a non-smoking area. Designated smoking areas that are safe from combustible materials should be provided.
Flammable and combustible materials: Combustible and flammable materials can significantly accelerate a fire as fuel. Fuels and other flammable liquids and gases must be stored away from fire-risk areas and monitored when in use.
Electrical wiring: Faulty wiring is a common construction fire safety hazard. All temporary electrical service lighting should be installed in accordance with National Electrical Code (NEC) requirements and regularly inspected. Corded temporary lighting should include cages on bulbs, be installed per manufacturer specifications, and be inspected and in good working order.
Tools and equipment: Construction tools, particularly rechargeable batteries, can overheat and cause fires. All batteries must be charged away from the construction area and in a safe location. Electrical batteries can have thermal runaway. If the battery cell temperature exceeds the critical level on either end, thermal runaway can destroy the battery or, even worse, start a fire. Charging stations should be outside the building under construction and stored safely.
Uninstalled fire protection: Without fire protection systems like fire alarms and sprinkler systems installed, the entire construction site is at increased risk of fire. Ensure that all workers know where fire extinguishers are placed, have access to them, and are trained to use one. Workers should also be trained to identify the signs of a fire starting.
General Safety Precautions for Fire Prevention in Construction
Prevent ignition: This includes preventing/controlling heat sources, for example, by banning smoking on site and implementing a regime of hot working permits. It also includes managing the interaction of heat sources by, for example, prohibiting potential fuels and the storage and handling of fuels. One typical example of these mitigating measures would be the recommendation to store highly flammable liquids in special containers. Measures to control deliberate fires are also deployed here.
Provide adequate extinguishers: Ensure that the construction site has enough fire extinguishers to prevent the spread of fires. Should an accidental fire start, a fire extinguisher can put it out if used correctly. Fire extinguishers must be approved and regularly maintained to always work as designed.
Have a fire plan and procedures: Always have a fire plan established. This fire plan should be part of the orientation procedure for all workers at the job site. Everyone who enters the construction site must know the safety plan in an emergency.
Keep the job site clean: Conduct regular housekeeping activities. Do not permit combustible debris and waste materials to accumulate where they can become a fuel source for a fire. Oily rags, wipes, or towels for cleaning off solvents and residue should be stored in covered metal containers. Dispose of combustible wastes and empty all bins at least once daily to avoid creating fire hazards.
Have a waste disposal plan: Keep the job site clear of rubbish and debris. Plan designated areas for waste with fire and emergency procedures to confine and deal with a fire should one break out. Keep waste containers in designated areas away from active construction areas and flammable substances.
References
WAC 296-155-260-Fire Protection (Construction)
Fires in Structures Under Construction | NFPA
1926.150 - Fire protection. | Occupational Safety and Health Administration (osha.gov)
