The location of standpipe hose valves in stairwells has been a topic of debate for some time. The International Building Code, 2015 edition requires standpipe hose valves to be at intermediate floor landings, while the 2018 edition requires them at main floor landings (Section 905.4(1) in both editions). The fire code official is permitted to allow hose valves at other locations. NFPA 14, Standard for the Installation of Standpipe and Hose Systems, requires hose valves to be located “at the main floor landing in exit stairways” (Section 7.3.2(1)), but also permits hose connections “to be located at the highest intermediate landings between floor levels in exit stairways where required by the AHJ.” Why are two locations permitted? Why do some fire departments want them on floor landings and others on intermediate landings?
There are two schools of thought on the location of hose valves in stair enclosures, and they stem from how firefighters connect hose to standpipes. First, the hose valve at the fire floor is nearly never used – the valve on the floor below is the preferred choice. This allows the hose valve to remain in a relatively smoke-free environment while the door to the fire floor is open. It is often forgotten that the door to the fire floor cannot be closed, as the hose must pass through the doorway. Any smoke and heat on the fire floor will enter the stair enclosure through the door that firefighters entered and travel upwards (which reinforces the need for stair pressurization).
Generally, at least 100 feet of hose will be connected to the standpipe hose valve below the fire floor, the nozzle advanced to the main landing at the fire floor, and any extra hose flaked out in a “horseshoe” shape on the stairs leading up beyond the fire floor landing. This allows gravity to help pull the hose down the stairs when the nozzle is advanced towards the fire. Nearly all fire departments use 2-1/2” diameter hose to connect to standpipes. There are some fire departments that will use 1-3/4” hose, but they are the minority. A 100-foot length of 2-1/2” fire hose, charged with water, weighs about 250 pounds which is a substantial load to move, especially in the confined space of an exit stairway or corridor.
Connecting hose to a landing a full floor below the fire floor will “use up” hose. Approximately 35 to 50 feet of hose is needed to wrap around a flight of stairs. The 100’ of hose that the firefighters were going to bring through the door onto the fire floor is then reduced to 50 to 65 feet of usable length. For this reason, firefighters often bring 150 or 200 feet of hose, which weighs approximately 375 or 500 pounds, and reduces the flow characteristics of the hose (adding an additional 7 to 8 psi of friction loss, and 5 pounds of elevation loss). The pre-1993 calculations for standpipes called for 65 psi, which assumed 100 feet of 2-1/2” hose and a nozzle with a 1-1/8” diameter flowing 250 gallons per minute. Extending the hose reduces the available volume. Modern editions of NFPA 14 require 100 psi; however, the reduction in flow still takes place as more hose is added.
Standpipe hose valves at main floor landings are simple to locate. Enter the stair enclosure and the hose valve should be nearby. In a potentially dark or smoke-filled stair, the standpipe hose valve can be readily located and connected to. A hose valve on a main floor landing also provides an escape route for firefighters. Firefighters will follow their hose line back to safety in an emergency, but when using a standpipe the hose line ends at a standpipe valve, not outdoors. A hose valve at a main landing is adjacent to a door that leads to a place of safety – the floor below the fire floor. The downside to using the main landing is one of space. Firefighters do not just connect a single fire hose, they will often connect a short (six to ten feet) length of fire hose with a gated wye and pressure gauge to the hose valve, then connect the main fire hose to the wye. A tool bag with equipment to connect to a stubborn hose valve or make minor repairs to the standpipe is also often left at the connection. The main landing now becomes crowded with hose and tools, blocking the door to the floor below the fire.
These factors – the amount of hose needed and working space – are what drive the discussion to utilize intermediate landings. The intermediate landing allows a shorter length of hose to reach the fire floor, as only 15 to 20 feet of hose are generally lost on the stair. It also eliminates the hose and tools blocking the stair landing on the floor below the fire, leaving the stair door free for use (but taking up space on the intermediate landing). The intermediate landing makes finding both the hose valve and an exit more complicated, though.
Regardless of which landing the hose valves are located on, the decision is ultimately up to the AHJ. Each fire department will determine which standpipe location best supports their tactics. Knowing both sides of the debate can help designers and installers work best with the local fire department.