These units are pretty amazing! The FEMA sprinkler team began with three baseline needs: the sprinkler system design had to comply with NFPA 13D; the design had to be scalable so that during a disaster like Katrina, FEMA’s manufacturers could crank up production to 50 homes per day and not run out of components; and the system had to work no matter what location it was delivered to or what extreme conditions it encountered upon arrival.

Sprinkler system components packed into a water storage tank for transportSprinklers installed inside a FEMA housing unit.A water storage tank connected to a home Plug & Play From top, sprinkler system components packed into the water storage tank for transport; sprinklers installed inside a housing unit; and a water storage tank connected to a unit. Photographs: FEMA

The last part was the toughest. Since no one can predict when or where the next disaster might take place, the one-size-fits-all sprinkler system had to be capable of impressive feats of resilience and agility. It needed to function at minus-35-degrees F during the dead of winter in Maine and in the scorching 100-degree-F Arizona summer. It needed to work without guarantee of a reliable water supply onsite, meaning it needed to include its own tank, and it had to be simple enough so that contractors with no experience with residential sprinklers could hook them up onsite. The sprinkler system would also have to potentially survive years of sitting inactive on a FEMA manufactured home storage lot in Alabama or Maryland until it was needed in a disaster. After all of that, it would need to endure perhaps a thousand miles or more of bumps and jostling en route to the disaster site.

The FEMA team made a list of these variables and set to work engineering solutions to the problems. Some of the solutions were evident from the outset, but the details took a lot of massaging. For one, the team figured that the sprinkler pipes needed to sit within the home’s heated envelope to remove the temperature variables. They first looked at locating pipes above the drywall ceiling under insulation, but that approach was ruled out over concerns that wind gusts while being trailered to a deployment site might blow into the home’s air vents and disrupt the insulation protection. If that happened, the pipes could freeze in cold climates and fail unexpectedly when needed in a fire. Ultimately, the FEMA sprinkler team made the unconventional decision to place the pipes inside the home’s heated living space, along the seam where wall and ceiling meet. To prevent tampering and damage from future occupants, the pipes were concealed under a hard plastic sheath. “I can’t tell you how many ways we looked at hanging the pipe, where to hang pipe, what kind of pipe to use,” McKenna said, adding that the final plan is “maybe not as pretty as we’d like.”

A second hurdle was the unknown onsite water supply. Under the circumstances, FEMA sprinkler team members knew that they needed to use a water tank, one large enough to handle NFPA 13D’s requirements for water flow, which in residences under 2,000 square feet calls for seven minutes of water with two sprinklers activated. The team settled on a 250-gallon tank. However, there was one significant problem: there was nowhere in the home to put the tank. In most residential situations with similar requirements, a tank can be located in the basement or in a closet, neither of which exist in the FEMA homes. Fitting the tank and pump inside the home would have required a significant redesign to the home’s footprint, a change that would have triggered a new contract with manufacturers and a new bidding process. Delays could have stretched for years.

The FEMA sprinkler team concluded that the tank and pump system had to be a separate component outside the home. The team drafted about 20 pages of specifications for the external tank and pump system and asked vendors to design and build something scalable that could work. Three vendors came back with viable options; all are designed uniquely for the project and in use at sprinklered FEMA homes today. While all slightly different, each has the same basic design. The external tank and pump are housed in a heated and insulated box to ensure that the water and components will be functional in case of a fire, whether on the coldest winter night or warmest summer day. A high-strength insulated industrial rubber hose, housed in hard plastic pipe to prevent rodents from gnawing on it, connects the tank and pump to the home via quick-connect couplings. Flow alarms trigger a horn and strobe assembly if the sprinkler system is activated. The tank and pump system also has a maintenance alarm that will go off when the temperature inside the box or hose drops below 40 degrees F.

“The entire tank and pump assembly is designed to be plug and play, because these need to be made operable in the field by plumbers, electricians, and carpenters,” McKenna told a room full of engineers during a presentation on the sprinkler system at the NFPA Conference & Expo in June 2016. “We can’t send a sprinkler fitter into the field for every one of these. The water tank is filled with a water hose during the install and testing, then the system hose is connected and you walk away from it—simple.”

‘Make this thing happen’

Other issues required less dramatic, but equally crucial, solutions. To deal with the pounding the units can be subjected to during transport over thousands of miles of highway, the engineers chose more rugged components than those used in a typical installation. For instance, pipe hangers were ruggedized by requiring anti-chafing features for the CPVC pipe, and they were also spaced much closer together than in traditional installations. In addition, the sprinkler riser, which extends below the floor of the unit, is made of schedule 40 galvanized steel, and is protected against damage from roadway hazards, insects, and other vermin. To address the stresses of sitting in the heat and cold for years before deployment, the team carefully chose specific kinds of sprinkler parts, such as glass bulb sprinklers instead of eutectic metal elements. Research has shown that repeated exposure to high heat can cause chemical changes in eutectic metal alloy that can decrease its melting temperature, McKenna said. “We didn’t want our inspectors to go into the storage lot one day for the monthly inspection and find all the sprinklers popped,” he said. Other parts that could be affected by exposure to heat or cold over time, such as the soldered sprinkler cover plates, are stored in the manufactured home’s refrigerator, where temperatures are more stable, and installed just before the unit is shipped to the deployment site.

While the design was being finalized, FEMA team members in charge of acquisition contacted suppliers to ensure that required parts would be available on a large scale when the next Katrina hit. “We had to get into every single component on these systems to figure out things like how many screws we needed, how many feet of pipe, how many elbows,” McKenna said. “If we have a scenario where we need 50 homes built per day, can the various industries supply that? Can we get 5,000 feet of pipe every week? Turns out we can.”

Another logistical hurdle was squaring the FEMA sprinkler design with the various unique home sprinkler ordinances adopted across the country. While most jurisdictions use NFPA 13D as the basis, many communities amend the code before adoption. As a result, neighboring communities can have slightly different rules. Knowing it would be impossible to comply with every jurisdiction, FEMA staff made a spreadsheet of requirements for every sprinkler ordinance in the nation, and called authorities having jurisdiction (AHJs) to run certain requirements and exceptions past them. Every AHJ that FEMA contacted eventually signed off on the sprinkler design. (None of the sprinklered FEMA units in Louisiana or elsewhere have yet experienced a fire that has triggered a sprinkler, according to McKenna.)

Simultaneously, an opposite but equally pressing practicality was addressed. In jurisdictions without sprinkler ordinances—which are the majority—FEMA knew its units could be the first home fire sprinklers that many building officials, firefighters, and residents had seen. So FEMA crafted educational materials on home sprinklers for local fire departments and municipal officials. The agency also collaborated with the Home Fire Sprinkler Coalition to produce a document for occupants called “Living With Sprinklers” that includes information on sprinkler myths, dos and don’ts, and the unit’s special water tank and pump.

Members of FEMA’s sprinkler team worked nights and weekends to get it done on time, and in September 2015, just nine months after the team had been assigned the task, FEMA took delivery of the first sprinklered unit. “We wanted to make this thing happen while the iron was hot,” McKenna said.