US fire departments respond to an average of 1,508 warehouse structure fires a year, with $323 million in direct property damage annually, according to NFPA’s 2025 analysis of warehouse structure fires. Only 18% of those fires start between midnight and 6 a.m. That same overnight window accounts for 38% of the damage. Divide 38 by 18 and the overnight share of loss runs a little over twice the overnight share of fires. Spread the $323 million evenly across the 1,508 fires and the average comes to a little over $214,000 per fire. The overnight fires don’t stay near that average. They run well above it, and the daytime fires run below it to make the numbers balance.
Nobody needs a study to guess that a fire is worse when nobody is there to catch it early. What the number does is put a size on that instinct, and point to where the exposure concentrates: not evenly across the clock, and not evenly across the floor.
Warehouses are one slice of a larger problem. The U.S. Fire Administration counted roughly 110,000 nonresidential building fires in 2023, with $3.16 billion in dollar loss, and its ten-year series through 2023 shows nonresidential fire deaths up 70% since 2014 even as injuries fell. Warehouse fires sit inside that trend with a loss profile shaped by what the buildings hold and by how many hours a week nobody is standing in them.
They also sit inside the fire category that carries most of the damage. The National Fire Sprinkler Association’s analysis of NFPA and NFIRS data, published in April 2024, found that structure fires are about 35% of all US fires but account for 77% of civilian fire deaths and 83% of dollar loss. A warehouse fire is a structure fire, so the overnight and storage-area splits below describe where loss concentrates inside the category that already concentrates it.
Storage areas carry most of the damage
Storage areas were the area of origin in 38% of warehouse fires and accounted for 34% of injuries, the same NFPA report found, but they took 72% of the direct property damage. A fire that starts in racked commodity has more fuel to work with and more distance to travel before a detector, a sprinkler head, or a person reaches it. The area of origin is close to a coin flip between storage and everything else: 38% storage, 62% everywhere else in the building. The damage split is not close at all: storage takes 72%, everywhere else takes the remaining 28%.
Operating equipment and arcing lead the causes
Operating equipment was the leading heat source in warehouse fires, responsible for 44% of fires, 36% of injuries, and 35% of the property damage, per NFPA’s 2025 warehouse fire data. Arcing alone caused 14% of fires but 21% of the damage, a heavier share of loss than its share of ignitions.
The same report found that warehouses occupied and operating at the time of the fire accounted for 71% of fires and 92% of the damage. Vacant and unsecured buildings made up 14% of fires. Those two categories don’t cover every warehouse fire; the remaining 15% falls into other occupancy statuses the report tracks separately. Even so, the top of the range makes the point on its own. That runs against the assumption that an idle building is the risk to worry about. The bigger exposure sits with a warehouse that is running: equipment under continuous load, more connections and components that can arc, overheat, or fail, and more of that equipment operating unattended once the shift ends.
What sprinklers change
NFPA’s 2024 research on US sprinkler experience found the civilian fire death rate was 90% lower in properties with wet-pipe or dry-pipe sprinklers present than in properties with none. Sprinklers operated in 92% of fires large enough to trigger them and controlled the fire in 97% of the fires where they operated. In 77% of those fires, a single sprinkler head did the job, meaning the fire was caught small enough that it never spread far enough to trip a second head.
A system that activates on a fire in a storage rack at 3 a.m. is doing the work nobody is there to do by hand. That is the point of the overnight and storage-area numbers above: the hours and the areas where a fire is least likely to be caught by a person are exactly where automatic suppression is doing the most.
Why dry-pipe systems concentrate in storage buildings
The same NFPA sprinkler research found that wet-pipe systems are the leading sprinkler type in use across US properties generally, but dry-pipe systems show up disproportionately often in storage occupancies, where offices and mercantile space are predominantly wet-pipe.
That distribution tracks with the buildings themselves. Storage space, especially unheated bays and dock areas, carries a freeze risk that a water-filled pipe network does not tolerate, so dry-pipe design is the practical choice there. It also comes with a maintenance and freeze-protection schedule suited to a storage occupancy, not one carried over from an office building down the road. Given that storage areas already carry 72% of warehouse fire damage, a dry-pipe system protecting one of them is not a place to let inspection intervals slide.
Map your unattended hours against your coverage
The numbers above describe the industry. Checking where a specific warehouse sits inside them takes four steps, and none of them require new equipment to answer, just the current system drawings and the current staffing schedule, side by side.
Start with the clock, not the generic midnight-to-6-a.m. window in the national data. Write down the actual time the last person leaves the floor and the time the first person arrives, including nights the building runs with nobody on it and weekends when it may be closed entirely. For a single-shift operation that might be an eight-hour gap. For a warehouse staffed only on weekdays, it is closer to sixty hours a week.
Next, check where detection sits inside that gap. Given that storage areas carry the largest share of warehouse fire damage, coverage in the racks and bulk storage bays matters more than coverage at the dock door or the front office. A layout built around where people walk during the day can leave the highest-value storage the least protected during the hours nobody is walking anywhere.
Third, confirm whether an alarm event reaches someone off-site during those unattended hours, or only sounds a local horn. A local horn does its job when a person is present to hear it. During an unattended interval, coverage depends on the signal reaching a monitoring point, not on how loud it is.
Fourth, if the storage areas run on a dry-pipe system, confirm the inspection and test schedule accounts for freeze protection and a testing frequency suited to a storage occupancy, not one carried over from a general office schedule.
Run those four checks and the gap, if there is one, tends to show up fast. Most warehouses have some detection and some monitoring already in place. The question is whether either one was designed around the hours and the areas where the loss concentrates, or just around where the building’s front door happens to be.
What this looks like when handled well
Versys installs and monitors fire alarm systems for warehouses and distribution centers across Kentucky and Southern Indiana, working primarily with Honeywell Silent Knight and Firelite equipment. The work follows the same logic as the data above: detection placed in storage areas and around operating equipment, not concentrated near the entrance where foot traffic already provides a second layer of awareness; a monitoring connection that treats a 3 a.m. alarm the same way it treats one at 3 p.m.; and an inspection schedule that fits a dry-pipe storage system rather than an office building. The company also provides 24/7 emergency support if a device faults or a system needs attention outside business hours.
The next step is to run the four checks above against your own building. If the unattended hours and the detection coverage do not line up, call Versys at (270) 358-2200.
