Throughout our history in the fire service and since its inception to building construction, parapet walls have injured and killed several firefighters. Many departments respond to buildings with these walls on daily basis and some departments don’t ever encounter these but there’s no such thing as “never” in the fire service.
So with that, what are parapet walls?
For starters, parapet walls are those that extend above the roof level giving the illusion to street viewers that the building is taller than it actually is and could range from inches to several feet above the roof level. Despite its decorative appearance the wall provides protection to the building from the elements as well. Although they are commonly known as an extended wall above the roof level, they serve multiple purposes for the building itself and we will list a few of them for you and then explain each.
1. Fire Protection
2. Improve wind-up lift resistance.
3. Vapor pressure relief for older masonry buildings
4. Scupper drains
Extending the wall above the roof level, these walls prevent fire spread from going up the exterior of a building which would almost immediately ignite any and all roofing membrane.
Wind-up lift resistance
When wind blows against a building, it produces vortices at the roof edges causing these forces to lift the roof edge and peel back the roofing system. By having a parapet wall in place, this will help prevent any elevated wind pressure from compromising the roof edge.
Vapor Pressure Relief
Older masonry buildings that have a parapet wall also provide vapor pressure relief. Water, as we know cannot pass through the roofing membrane so the vapor pressure relief was designed to have water find its way to the roof edge and exit through back side of the parapet. Usually these are finished with permeable clay bricks.
Scupper drains are openings in the side walls of an open-air structure, found at the bottom of a parapet wall. They are used to allow rain or other liquids to flow off the side of the structure instead of pooling within the walls or possible collapsing the roof.
Hazards with parapet walls
During fire operations parapets are prone to failure. Mostly, these walls are exposed to all elements and could possibly fall into disrepair but with regular maintenance of a structure these walls should be checked and maintained as need be. Many of these walls are supported by an horizontal steel I-beam that runs the length of the front of the structure. The hazard that comes along with this is, should fire reach the cockloft, this steel beam can be exposed to high heat and thus expand causing the wall to potentially fail. There is really no one way that these walls will fail. They could fall as one piece or they could crumble and fall in pieces.
Changing occupancies in the structure is another potential hazard with parapets. The reason behind this is the new owner or renter’s signage that is placed over the existing parapet. Some signs are anchored through the wall itself while others can be mounted from around and over the existing parapet. Either way these add to the load of the wall and increasing its fail potential should it be put under stress in fire or collapse conditions.
What do look out for and how to work with these walls
When working on a structure with a parapet, here are some tips to keep in mind:
1. Set up a collapse zone and monitor the walls for signs of cracking or bowing and notify the IC immediately. Keep in mind that these walls could collapse at any given time even after the fire has been under control.
2. Check or exposures throughout the interior and exterior making sure no fire as reached the cockloft putting extra stress on the parapet.
3. When setting up an aerial device, look for scuppers to determine the height of the parapet with relationship to the scuppers. If you don’t think you can make the roof due it the walls height, try and look for a secondary means on to the roof. Don’t take a chance trying to jump up and grab the ladder from the roof.
4. Before stepping on to the roof from the ladder, sound the roof with your tool. Usually a 6 foot hook of any kind will work best.
5. Lastly, never assume during fire operations that the parapet was engineered to take the weight and forces of the additional dead and live loads being added to the structure.
Until next time; work hard, stay safe and live inspired.
About the Author
NICHOLAS J. HIGGINS is a firefighter with 15 years in the fire service all within departments in Piscataway, NJ. Nick has held the ranks of Lieutenant and Captain as well as being a township elected District Fire Commissioner for 1 term (3 years) in Piscataway, NJ. He is also a NJ State certified level 2 fire instructor. He holds a B.S. in Accounting from Kean University working in Corporate Taxation and is the founder/contributor of the Firehouse Tribune website.