Defensible Space
Having defensible space is essential to improving your property’s chance of surviving a wildfire. Defensible space is the buffer you create between a building on your property and the trees, shrubs, grasses or any other wildland areas surrounding it. This buffer is needed to slow or stop the spread of fire and it helps protect your home from catching fire—either from direct flame contact or radiant heat.
Your house and outbuildings are potential fuel in a fire-prone environment. To help your home survive a wildfire, create defensible space between your home and its surroundings by at least 100 feet or more. This defensible space gives firefighters an opportunity to safely defend your home and other structures from a wildfire while breaking up pathways for fire that can lead to a home’s ignition. Firefighters can’t always protect every individual home, so it’s your responsibility to take action.
Zone 1 extends from the house itself out to 30 feet.
Zone 2 extends from 30 feet out to 100 feet (or more on steeper slopes).
And Zone 3 is the area beyond Zone 2 that extends out to the property line.
How you landscape and maintain the vegetation in these zones will have a big influence on the survival of your home in a wildfire.
Zone 1.
Lean, Clean, and Green area: The portion of your property at least 30 feet from the home should be Lean, Clean, and Green. Lean means that fire-prone, flammable vegetation is discouraged within 30 feet of the house, and vegetation in general is maintained at a low density. Clean means there is no accumulation of dead vegetation or flammable debris within this area. Green means that plants are kept healthy, green, and sufficiently watered during fire season. For most homeowners, the Lean, Clean, and Green area is the residential landscape. This zone often has irrigation, contains ornamental plants, and should be maintained annually.
❏ Trim back fire-resistant shrubs.
❏ Prune mature trees to at least 10 feet.
❏ Remove dead plant material such as leaves, needles, and twigs.
❏ Replace flammable plants with fire-resistant plants.
❏ Keep grass watered (green) and mowed to 4 inches.
Zone 1A.
Noncombustible area: Create a Noncombustible Area at least 5 feet wide around the base of your home. This area needs to have a very low potential for ignition from flying embers. Use gravel, rock mulches, or hard surfaces such as brick and pavers. Keep this area free of woodpiles, wood mulches, and flammable shrubs such as juniper. This area should be maintained annually.
❏ Remove dead plant material that has accumulated such as leaves, needles, and twigs.
❏ Keep gutters and roofs cleaned of debris.
❏ Make sure any overhanging limbs are trimmed back at least 10 feet or more from the roof
Zone 2.
Outer defensible space: This area extends from the 30 foot “Lean, Clean and Green” area out to at least 100 feet, and up to 200 feet on steeper slopes with thicker vegetation. It usually lies beyond the residential landscape and often consists of naturally occurring plants such as conifer and hardwood trees, brush, weeds, and grass.
Annual maintenance tasks in this zone:
❏ Remove dead fine vegetation, including dead shrubs, fallen branches, thick accumulations of needles and leaves, etc.
❏ Before fire season, mow grass to 4 inches or less in height.
Do the following every few years, or on a portion of the area every year, so that the entire area is treated within a 5- to 8-year timespan:
❏ Thin out dense patches of trees and shrubs to create separation between them in order to slow the spread of fire. If you want to keep a particular small dense clump or patch of trees and shrubs for a visual screen, clear out 5 to 10 feet around it, creating an island and ensuring that you are breaking up the continuity of fuels.
❏ Reduce ladder fuels by removing low tree branches and shrubs growing directly under trees.
❏ Remove invasive weeds such as blackberries, cheatgrass, and Scotch broom
Zone 3.
Wildland fuel reduction area: Some properties extend beyond the home’s defensible space. Fuels reduction is appropriate here too, but doesn’t need to be as intensive as inside the defensible space area/zone. The overall goal is to break up fuel and vegetation continuity (create spaces between plants so that fire has less chance to sustain itself). This zone should be maintained every few years, or a portion should be treated every year. Thin out dense patches of trees and shrubs to create separation between them. If you want to keep a particular dense clump or patch of trees and shrubs for a visual screen or wildlife habitat, clear out 5 to 10 feet around it to ensure you break up the continuity of fuels.
❏ Reduce “ladder fuels” such as smaller trees and brush growing under larger trees, and lower tree limbs.
❏ Reduce heavy accumulations of woody material (dead branches and twigs, slash, etc.).
❏ It’s fine to leave some brush patches, downed logs, and dead trees for habitat and soil benefits.
While having defensible space is not a guarantee of making it through a wildfire, it improves the likelyhood that it will. And when emergency resources are limited or exhausted, it could be your only line of defense. Sadly, we here in the Rogue Valley recently saw firsthand how destructive fire can be as-well-as how thin emergency services can get in such an event. Let’s all hope we never see that again.
Disclosure: Nearly everything written on this particular page has been copied and pasted from the OSU guide: Keeping Your Home and Property Safe from Wildfire. To read more from this handbook about wildfire safety in Southern Oregon please visit the Resource section of this site. There you will also find a selection of links to other relevant information for the Southwest Oregon area.
