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The Construction Site as the Fireground

Aug 11, 2023Aug 11, 2023

Construction sites present firefighters with all the obstacles of any structural fireground with an array of additional firefighting challenges.

By Jeffrey W. Moran

Photos by author except where noted

The building is the battleground or playing field for a structure fire. It is imperative that all firefighters possess and continually grow their knowledge and insight regarding building construction. You can’t successfully play a game without understanding the rules and playing parameters; fighting a building fire necessitates the same. This understanding must be expanded as the individual moves up in seniority, rank, and responsibility. Building construction books, articles, and classes commonly focus on completed, intact structures. Every jurisdiction has buildings. They didn’t just appear; they were once a construction site. Existing buildings may undergo renovations, expansions, or even demolition. It is when a building is incomplete that it presents a different set of challenges to the fire service. This article will present what these challenges are and the steps to address them.

Addressed here are access to the site, to the building, and within the building; challenges unique to construction sites and specific to incomplete buildings; the enhanced exposure concerns; and fire department resources.

The basic size-up factors found in COAL WAS WEALTH are the same, but the specifics must be altered to address the state of the building. As with any building, the size-up must start long before the response to an emergency. The preplan of a construction site differs in that the site is changing on a constant basis, so the preplan must be dynamic and continuously updated. Before an incident is the time to seek answers to all those “what if” questions. Keep in mind that one of the most basic considerations in a building is to defy gravity. Buildings are designed to resist four types of forces: tension, compression, shear, and torsion. The full resistance to these forces is only realized when the structural members are complete and fully intact. (1) A building undergoing construction, alterations, or demolition should be treated as not having 100% of its structural strength and thus at a greater risk of collapse. (2)

More than 75% of fires in structures under construction occurred in residential buildings (whether single or multiple dwelling is not specified), followed by mercantile or business, 6%; outside or special property, 5%; storage, 4%; and various other types with lesser percentages. The leading causes are cooking equipment, 19%; electrical distribution and lighting, 15%; heating equipment, 14%; intentional, 11%; and smoking materials, 4%. The study showed no significant variation in the number of fires by month, day of the week, or time of day. (3)

Research and read the reports on notable fires at construction and demolition sites. Some notable ones are the Deutsche Bank fire in New York City and the Avalon fires, two separate fires in Edgewater and Maplewood, New Jersey, respectively.

Access will be the first challenge you face. Is there access to the site? Is there security on site during nonwork hours that can aid in gaining access and locating the emergency?

Are the access roads adequate to support the weight of fire apparatus and wide enough for aerial operations? What effect will the water from the firefighting have on the roadway? What access means are blocked during nonwork hours and how are they blocked? Are there locked gates that can easily be forced or are heavy construction machines parked across the roads? Theft of materials, vandalism, and squatters are considerations the contractors will protect against, and you must be aware of what measures are being taken regarding this. This information will allow you to determine how to gain access to the site and then to the actual building(s).

Construction on roadways adjacent to the scene, especially underground utility work, may impede access. Pay special attention to open trenches and recently filled trenches as they may not be compacted enough to support apparatus or aerial stabilizers. What effect will your water flow have on these openings or just-filled trenches?

The area immediately adjacent to the building may impede gaining access to the building itself. Scaffolding on the building, possibly with loose materials on it, construction elevators, or construction equipment next the building can block access or present additional hazards to members. Particular attention should be paid to cranes, construction elevators, and scaffolding in terms of collapse hazards. (4) These may be attached to and depend on the building for stability. Open trenches, those not yet backfilled area around the foundation, or other holes can be found throughout the area. Tripping and slipping hazards may be presented by things such as protruding pipes, tree roots, debris, frozen uneven ground, ice, and mud, which will also be a slip hazard when carried into the building. There may be a number of impediments to access inside the building, which are covered in the building section.

Many of the construction site issues are addressed in the access section. The temporary roadways are often placed close to the building, where future parking will be located, for the convenience of moving supplies and operating equipment such as manlifts. This turns the fire apparatus into a potential exposure and puts it in the collapse zone. Determine what roadways will be paved, stone, or just graded soil intended for off-road construction equipment. Positioning apparatus at a distance and requiring long hand stretches, possibly 500 feet or more, is a consideration. Having additional companies assigned on the initial response is an option to meet this challenge.

The soil on site will have an effect on members, also. Sandy soil can be soft and more difficult to walk through, especially loose sand. Heavier soils, such as clay, are slippery when wet, and its mud will cling to footwear, adding weight, which will add to fatigue. Loose soils will allow members’ feet to sink in, particularly when they are wet, which may cause the member to become stuck. Soil will also be a factor in a call for trench collapse/rescue. Compliance with Occupational Safety and Health Administration regulations (5) and training in trench rescue is a must if the department performs such services. Members must stay out of and away from the edge of unprotected excavations.

Fires in incomplete buildings can require large volumes of water. What water supplies are available? Will there be long supply line stretches, water shuttles, and drafting, or is it a nonintervention situation? Larger construction sites generally include the installation of a water main system within the site. Keep your information current on where active fire hydrants are located, which standpipes and sprinklers are supplied, and which are complete enough to use but not connected to the water mains. Have appropriate and adequate resources respond to overcome the water supply obstacles.

This article will not go in depth into the types, materials, and fire behavior characteristics of a building but will rather highlight the unique hazards presented by a building under construction/demolition or a combination of both. The first step is to follow a Branniganism: “Undress the building when analyzing how and where the fire will spread in a building.” Francis L. Brannigan. (6)

The target building site range will be from a small, single-story structure to a high rise. The area of the building can range from a few hundred square feet to over a full square city block (photos 6, 7). The type of construction can be any one type or a combination of types. A common structure seen in urban and suburban areas today is the mid-rise (5-10 story). These are Type I for the first one to three stories then type V for three to five stories with the occupancies of commercial and/or vehicle parking on the Type I floors and residential on the Type V floors. The intended occupancy plays a significant role in how the building is constructed and how each floor is laid out. (7)

The critical information\regarding the building(s) to determine are:

The first consideration is the nature of the alarm. Is it a fire, construction accident, a medical emergency, removal of an individual, or a miscellaneous service call? If you’re dealing with a fire, firefighters must complete a primary search since there may be workers, security guards, squatters, vandals, or thieves trapped. During interior fire operations, members must pay particular attention to rapidly changing conditions. This is amplified by the unprotected openings on and between floors.

Hazards encountered more commonly in buildings under construction than completed buildings are floor openings or floor edges such as on a balcony. The guard rails for these are designed to protect a person walking upright in a clear atmosphere. Additionally, the guards may not exist or have been temporarily removed or ongoing work. The standard for a floor opening guardrail only requires that it withstand a force of 200 pounds applied in a downward or outward direction. (8) How many firefighters in gear would apply a force of less than 200 pounds when falling?

During construction there will be various materials and equipment stored on the floors, often being a concentrated load. Included can be combustible building materials such as lumber, polystyrene insulation, wiring, plastic, or metal piping, possibly in large quantities and in an open floor area. Flammable finishing products and adhesives, fuels for equipment and compressed gases (acetylene, oxygen, propane) may be found in various locations within the building. Each contractor or trade will have their own. Large building projects will also have multiple shanties/sheds and enclosed workshop areas for different trades or contractors. Forklifts, skid steers, and other small mobile equipment can also be in use on any floor of a larger building. These may be diesel, propane, or electric powered, which means fuel storage or a high-voltage charging station and possibly lithium-ion batteries. (9) A plan to establish a Class B foam operation and or a high-volume fire flow must be in place for these potential incidents.

Poured concrete structures present specific challenges while being constructed. The concrete is initially held in place by forms, commonly called falsework, which is often wood. The wood is reused as the building progresses. It is subject to drying out, especially when heating is used to help cure concrete in winter, and is frequently sprayed with oil to keep the concrete from sticking to it. The wood will burn rapidly, leading to the early collapse of the “green” concrete. (10) Even without fire there is potential for the weight of the wet, or “green,”’” concrete to cause a falsework failure.

Scaffolding, construction hoists, or elevators and cranes may hinder exterior access and present a collapse hazard, particularly when exposed to the heat of a fire. (11) These must be factored when establishing a collapse zone. A crane tower or boom can collapse intact, thus making the collapse zone the full height of the crane. Scaffolding often is enclosed with netting to prevent materials from falling or blowing off but it also restricts fire department access from the exterior. A working stock of materials are often stored on the scaffolding, increasing the falling load in a collapse, which may cause secondary collapses or structural failure.

Challenges and hazards presented to members in an incomplete building can cause injuries and/or hinder operations. Some of these are vertical construction ladders in place of not yet installed stairs, temporary partitions, access to some floors blocked for various reasons, construction shanties/enclosures on floors of larger buildings, building materials storage, poorly guarded floor openings, and temporary low-hanging wiring or other utilities. A reminder that the floor opening guarding and temporary stair railings are designed for upright walking in clear visibility—don’t crawl blindly into a hole.

Fire protection systems in construction or demolition will at best be incomplete. Systems may not have been connected to the water supply or have the supply shut down, usually to avoid water flow and damage. Systems with no active water supply might have the standpipe or drain valves left in the position and/or have missing segments at multiple locations. This will delay getting water on the fire and put firefighters at risk. (12) Have all fire protection lines, especially in the building, obviously marked (spray paint, bright) to hopefully keep them intact.

Members may encounter unusual temporary walls, enclosures, isolated sections related to abatement projects (i.e. asbestos), and missing stairs, escalators, and elevators, particularly in demolition projects. The temporary walls and enclosures are most often plywood or plastic sheeting. (13) The sheeting will readily fall and entangle members. In addition to large open floor areas, the exterior enclosure may not be complete, giving the fire an unlimited air supply and possibly creating a wind condition on the floors. Floors that are supported by parallel-chord wood trusses will create what is essentially a cockloft between each floor. While this presents the same fire spread problem as a top floor cockloft, this problem is enhanced by the not-yet-enclosed space having a readily available air supply, potentially causing wind-driven fire spread.

Exposure protection is critical in that these fires develop very rapidly and burn hot. Think: free burning.

An open wood frame building is essentially a bonfire. Now imagine it at seven stories in the air. The normal exposure routes of conduction, convection and radiation are present as well as flying embers being carried in the winds. Embers can fall and start additional fires within the building or on site, or they may travel off site to ignite other fires. (14) Large fire have created their own winds, and so, even with calm weather, winds can be a factor. Brand patrols must be established and possibly using master streams to extinguish the embers in the wind at the fire scene if the water supply permits.


During the project:


Construction sites present all the challenges of any structural fireground with an array of additional challenges, including problems with access, water supply, fire spread, and injury risk. Access to the entire site—to the building as a whole or sections within the building—may be difficult. Water supply to the site may be limited or even nonexistent. Fire suppression systems may not have a water supply or be incomplete. Incomplete or unsupplied systems often have outlet valves open or inline sectional valves closed, both of which will impede operations.

The building(s) will have large, open-floor areas, unprotected structural components, unprotected openings between areas, and floors and/or open exterior walls. These all promote an unlimited air supply to the fire and accelerated fire spread. A large, wood-frame building can rapidly become a bonfire, presenting an extreme exposure problem.

The condition of the grounds around the building(s) and the incomplete interior present numerous hazards for potential injuries, especially at night. These can be holes in the ground or floor, debris lying about, sharp protrusions (nails), entanglement hazards (wires, pipes, and ceiling grids), or energized temporary electric supplies.

Start your preplanning when the project is being planned and continue updating it throughout the life of the project. The bigger the project, the more encompassing and dynamic the plan must be.

Jeffrey W. Moran is a battalion chief (ret.) and fire commissioner with the Woodbridge (NJ) Fire Department with 41 years of service. He has a master’s in public administration and undergraduate degrees in business administration and fire science technology.

(1) Brannigan, Francis L., & Corbett, Glenn P. Brannigan’s Building Construction for the Fire Service (6th ed.), 2021. Jones and Bartlett. p13.

(2) Brannigan, pp 65-70.

(3) Campbell, Richard. (2022) “Fires in Structures under Construction.” NFPA Research.

(4) Brannigan, p 63.

(5) 29CFR1926 Subpart P. (Oct 1989, Feb. 1994, Aug. 2020): U.S. Department of Labor.

(6) Brannigan, p5.

(7) Brannigan, p 420.

(8) 29CFR1926 Subpart R. (Jan 2001): U. S. Department of Labor

(9) and

(10) Dunn, Vincent. Collapse of Burning Buildings. Fire Engineering. 1988.

(11) Dunn, pp 207-209.

(12) NIOSH, Death in the Line of Duty F207-37. National Institute for Occupational Safety and Health. August 2010.

(13) NIOSH.

(14) Dunn, pp 212-213.

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