Exterior wildfire sprinklers: what they do and what they cannot

What they are

An exterior wildfire sprinkler system wets the roof, eaves, and the area around the house ahead of an approaching fire, with the goal of raising humidity and putting out embers before they find a way in. Systems range from a few roof heads on a garden hose fitting to engineered setups with their own tank, pump, and remote or automatic activation.

What they are not

• Not the indoor 13D system. That one handles a fire that starts inside and does nothing for embers.
• Not a code requirement. California’s wildland urban interface rules are about roofing, vents, siding and defensible space, not sprinklers.
• Not a guarantee. In a major fire, water pressure drops and power fails. A system that depends on either may not run when it matters.

What makes one worth having

Its own water and its own power. A tank sized to run for a useful stretch, a pump that does not need the grid, and activation that does not need you to be home. Anything short of that is a hose on the roof, which is not nothing, but should be priced like what it is.

Do the other things first

Ember resistant vents, a Class A roof, cleared gutters, non combustible siding near grade, and defensible space do more for most houses than any sprinkler and are what the state rules and most carriers actually look at. Exterior sprinklers go on top of that list, not in place of it.

Who installs them

Exterior systems that tie into the home’s water supply or add a tank and pump are fire protection work. The contractor we connect you with can tell you whether what you have in mind is a real system or a hose, and quote the real one. The well water page covers the tank and pump side, which is shared with rural indoor systems.