How Does a Fire Sprinkler System Work?

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How Does a Fire Sprinkler System Work?

When it comes to protecting your family and home, you can never be too prepared. As wildfire season ramps up in summer 2020, we’ve received dozens of inquiries from the community asking us about the efficiency of fire sprinkler systems in combating wildfire. One of the most commonly asked questions we hear is, “How does a fire sprinkler system work?” Read on to find all the answers.

If you have additional questions, our team at Frontline Wildfire Systems welcomes your phone call or email. Get in touch today for more information.

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Two Types of Fire Sprinklers: Interior & Exterior

There are two main types of fire sprinklers that we will focus on in this post: interior sprinklers and exterior sprinklers. As their names imply, one system is installed on the exterior of the home, while the other is installed in the interior of the home. Installing both types of sprinklers in your home can provide maximum protection from wildfire. Let’s take a closer look at each:

Interior Sprinklers

Interior fire sprinklers are installed within the interior of your home. Their purpose is to protect your home from fires that begin within your property, like kitchen fires, electrical fires, etc. But they can also be useful to protect your home during wildfires, as the interior of your home can ignite even when the exterior does not. This is because embers can enter your home through windows or vents, igniting objects within your home. With an interior sprinkler system in place, you can prevent extensive damage from burning and smoke by stopping a fire within your home at an early stage.

A special note for California residents: As of 2011, the 2010 California Building Standards Code (NFPA 13D) requires that all new single-family and multi-family dwellings and townhome constructions have an automatic interior sprinkler system installed.

How Does It Work?

Interior sprinkler systems are “charged” or “wet” systems, meaning that they have pressured water sitting in all of the pipes behind the sprinkler head, ready to spray when activated. Interior systems are designed to trigger automatically when substantial heat is detected. Sprinkler heads in the system contain a special wick that melts in the presence of heat, eventually breaking the seal on the head. When the seal is broken, the sprinkler system activates to douse any flames that are present. Note that the NFPA 13D requires interior sprinkler systems to discharge for at least 10 minutes, with a minimum discharge of 13 gallons per minute per sprinkler.


In California, interior sprinklers are required to be installed during new construction. They may also be installed during large renovations. The NFPA provides a full set of codes and standards when it comes to the installation of interior fire sprinklers in California homes. The code includes guidelines on everything from the types of permissible sprinklers to sprinkler positions, flow rates, location, and more.


Interior sprinkler systems have been proven to be effective at controlling and even extinguishing fires, often before a fire department crew can arrive. In cases where the fire cannot be extinguished, interior sprinklers can allow residents enough time to escape while helping to prevent extensive damage:

  • The risk of property damage can be reduced by 70% with sprinklers present (NFPA)
  • The risk of dying in a home fire is 85% lower if sprinklers are present (NFPA)

Exterior Sprinklers

Exterior fire sprinkler systems are installed on the exterior of a home or building and are used to prevent ignition during a wildfire. By wetting and saturating the outside of your home, property, and surrounding land, these sprinkler systems can prevent ignition and destruction from embers, the number one cause of damage from wildfires.

The Frontline Wildfire Defense System is the industry’s leading exterior sprinkler system, offering:

  • Remote activation for 24/7 protection from anywhere.
  • Built-in battery backup and cell and satellite communication.
  • Environmentally friendly and biodegradable Class A foam.
  • Municipal, well, pool and emergency water tank supply options.
  • Wildfire tracking and system activation using the Frontline app

View our FAQ page to explore more commonly asked questions and answers.

How Does It Work?

Unlike interior sprinklers, which are “wet” or “charged” systems, exterior sprinklers are “dry” systems until activated. Whereas interior sprinklers are intended to be fire extinguishers, exterior sprinklers are intended to prevent a fire before it starts. Imagine a downpour on your house. That’s what ember showers are like—except, instead of rain, it’s embers looking for a weakness in your home’s defense. Proactive hydration is the best defense against embers. For this reason, an automatic activation system is not the best design for exterior sprinklers.

If your system were to wait until heat or fire were detected to activate, the embers may have already found a dry combustible material on or around your house. Instead, exterior sprinkler systems are most effective when homeowners proactively activate them before the embers arrive.

Innovative exterior sprinkler systems like the Frontline Wildfire Defense System allow for remote activation—so you can activate your system from anywhere even when internet and cell service is down. This is especially important when evacuation orders are in place, allowing you plenty of time to evacuate while ensuring your system is activated.

Another key feature of the Frontline Wildfire Defense System is its unique foam proportioning system, which mixes water with environmentally friendly, biodegradable Class A foam, providing greater fire protection than water alone. The foam is a wetting agent, or surfactant. Its job is to break the surface tension of water so the water sticks to and hydrates fuels faster and longer, instead of beading up and rolling off building materials and furniture.


For new homes in the design or construction phase, exterior sprinklers can be installed alongside interior sprinklers with the pipes integrated in the walls and sprinklers penetrating the roof or eaves, much like a bathroom vent. For existing homes, the system is installed on the side of the house, like a Powerwall and solar system, with copper pipes running discreetly to sprinklers on the roof ridges or eaves. s.

At Frontline Wildfire Defense, professional installation of an exterior fire sprinkler system typically takes two to five days. Our process begins with a complimentary consultation call, followed by a preliminary design proposal. Municipal, well, pool and emergency water tank supply options are available, and we can design the system to blend in with your home’s architecture, hiding it from view.


As fire scientist Jack Cohen has noted, “the wildland fire problem is a home ignition problem, not a wildfire control problem.” The installation of an exterior fire sprinkler system is an effective way to protect your home from igniting during a wildfire.

Since interior sprinklers have been around longer and required by building code, there is much more compelling data on their effectiveness. However, the underlying principle is the same for exterior systems: wet fuels (homes, furniture, landscape) do not burn. Every fire department across the country uses water and Class A foam to prevent fires from spreading or “spotting” from house to house. Fire chiefs and insurance companies are recommending Frontline’s system as a way to protect homes, while protecting firefighter lives.

In addition to the science behind why water prevents ignition, here are several case studies indicating the value of exterior sprinkler systems:

  • Frontline system saves home in 2018 Roosevelt Fire while 55 of 150 homes in neighborhood were destroyed
  • During the Ham Lake Fire in 2007, all 188 properties that had exterior sprinkler systems installed survived the fire, while more than 100 other neighboring properties were destroyed.
  • During the Camp Fire of 2018, owners of the few homes left standing had exterior sprinklers installed
  • Water treated with Class A foam (as in the Frontline Wildfire Defense System) can wet a Class A fuel up to 20 times more rapidly than untreated water (NIFT)

Protect Your Home Today

We hope you found all the answers you needed on how a fire sprinkler system works. At Frontline Wildfire Defense, our mission is to provide peace of mind and security for all of our customers and their communities. If you’re ready to take the next step, contact us for a free quote and consultation. Our team is happy to answer any questions you have on how to protect and safeguard your home from wildfire with an exterior sprinkler system.

The Frontline Wildfire Defense exterior sprinkler system can protect your home from wildfire with:

  • Remote activation for 24/7 protection from anywhere
  • Built-in battery backup and satellite communication
  • Environmentally friendly, biodegradable Class A foam
  • Municipal, well, pool and emergency water tank supply options
  • Wildfire tracking and remote system activation using the Frontline app

For more information on how Frontline Wildfire Defense can help safeguard your home, contact us today for a free consultation.

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