FEMA specifically recommends an outdoor fire sprinkler system to help with Home Hardening stating: PLAN FOR ACCESS TO WATER, Purchase and install external sprinkler systems with dedicated power sources or a water tank, if no water source is available. Connect garden hoses long enough to reach any area of the home and fill garbage cans, tubs, or other large containers with water.

Click here to read FEMA’s full recommendations of Home Hardening   

Exterior Fire Sprinklers

Characteristics
- The purpose of an exterior fire sprinkler system is to saturate the exterior of the building.
- Exterior sprinkler systems can be installed during new construction or on existing buildings.
- They are commonly installed on the roof along the ridge line or underneath the eaves and along soffits.
- Exterior sprinklers can be activated automatically by low-voltage heat detectors or manually by occupants before they evacuate the home.
- Exterior sprinklers can include a warning system that notifies occupants and emergency response personnel of a developing fire.
- Some landscape sprinklers are designed and installed to provide protection from a wildfire to landscape areas immediately surrounding a building.
- An exterior sprinkler system can be installed so that it is substantially hidden from view.

Guidance
Exterior sprinklers mounted on the building can be configured to use water piping through the attic or roof or to use piping on the exterior of the structure. If interior pipes are used, exterior sprinklers can be installed in conjunction with interior sprinklers (see Figure 2). A standalone system that includes a pressurized holding tank can be considered to ensure an adequate water supply. See the information about water supply under interior fire sprinklers above.

Considerations
- If exterior sprinklers are installed in areas where freezing temperatures occur, special provisions such as dry sprinklers are required to prevent water in the piping from freezing and rupturing it. In a dry sprinkler system, the portion of piping that is vulnerable to freezing is not charged with water until a fire opens a valve and releases water into the piping.
- Exterior sprinklers can provide added protection when used in conjunction with fire-resistant construction materials (see Fact Sheets #5–14) and defensible space (see Fact Sheet #4, Defensible Space).
- Polymer gels, Class A foam products, and other long-term fire retardants can be applied to structures prior to fire impingement and provide greater thermal protection than water alone. Many of these products are available to homeowners in self-contained application units and can be applied with an attachment to a garden hose or integrated into the home’s exterior sprinkler systems.


Effectiveness
- If exterior fire sprinklers require manual activation, occupants must activate the system expeditiously for the system to be effective.
- High winds that are frequently a byproduct of major fire activity can significantly degrade the effectiveness of an exterior sprinkler system.
- Manually applied fire-protection materials such as Class A foam products can be effective if time is available to treat the home. To be effective, the fire-protection material must be applied within the time frame identified by the product manufacturer

Download Home Builder's Guide to Construction in Wildfire Zones Here