Creating Defensible Space
If you live in the Rogue Valley or surrounding areas, you may have noticed the lush vegetation, which, while beautiful, can create wildfire risks during the hot, dry summer months. Managing this growth can be overwhelming, especially after years without cleanup or when starting a new landscape. The good news is that once the initial work is done, upkeep becomes much easier! We follow National Fire Protection Association (NFPA) guidelines to help you prepare your land with proper defensible space. Here we will go over The Home Ignition Zone and Defensible Space.
What is the Home Ignition Zone (HIZ)?
The Home Ignition Zone is a buffer of up to 200 feet around your house. It is the defensible space that you can cultivate as a safety bubble to protect your home. Maintaining the Home Ignition Zone can slow or stop the spread of wildfire, defend your house from fire and embers, and protect firefighters who are working to save your home.
The National Fire Protection Association (NFPA) divides the Home Ignition Zone into three sections: the Immediate Zone, the Intermediate Zone, and the Extended Zone.* Other sources may refer to these sections differently; for example, FEMA refers to these areas as Zone 1, Zone 2, and Zone 3.*
The concept of the home ignition zone was developed by retired USDA Forest Service fire scientist Jack Cohen in the late 1990s, following some breakthrough experimental research into how homes ignite due to the effects of radiant heat.
Creating Adequate
Defensible Space
and What It Means
Defensible space is the buffer created between your home or business and the grass, trees, shrubs, or any wildland area surrounding it. Proper defensible space can slow or stop the spread of wildfire and help protect your home or business.
Well-maintained defensible space can increase your home’s chance of survival by 75%.
The National Fire Protection Association (NFPA) recommends a defensible space, free of leaves, debris, or other flammable materials, of up to 200 feet from a structure. Think about getting the three zones established around your house or business.
Zone 1: The Immediate Zone
The Immediate Zone:
The home and the area 0-5’ from the furthest attached exterior point of the home; defined as a non-combustible area. Science tells us this is the most important zone to take immediate action on as it is the most vulnerable to embers. START WITH THE HOUSE ITSELF then move into the landscaping section of the Immediate Zone.
Ember cast from a wildfire could potentially ignite leaf litter and other debris found in gutters and on rooftops.
Preventative Action:
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Clean roofs and gutters of dead leaves, debris and pine needles that could catch embers.
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Replace or repair any loose or missing shingles or roof tiles to prevent ember penetration.
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Reduce embers that could pass through vents in the eaves by installing 1/8 inch metal mesh screening.
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Clean debris from exterior attic vents and install 1/8 inch metal mesh screening to reduce embers.
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Repair or replace damaged or loose window screens and any broken windows.
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Screen or box-in areas below patios and decks with wire mesh to prevent debris and combustible materials from accumulating.
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Move any flammable material away from wall exteriors – mulch, flammable plants, leaves and needles, firewood piles – anything that can burn.
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Remove anything stored underneath decks or porches.
Zone 2: The Intermediate Zone
The Intermediate Zone:
5'-30’ from the furthest exterior point of the home. Landscaping / hardscaping- employing careful landscaping or creating breaks that can help influence and decrease fire behavior
While it makes a great view, fires can easily transition from the ground to the canopy and burn from tree to tree in this environment.
Preventative Action:
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Clear vegetation from under large stationary propane tanks, down to mineral soil
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Create fuel breaks with driveways, walkways/paths, patios, and decks.
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Keep lawns and native grasses mowed to a height of four inches.
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Remove ladder fuels (vegetation under trees) so a surface fire cannot reach the crowns. Prune trees up to six to ten feet from the ground; for shorter trees do not exceed 1/3 of the overall tree height.
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Space trees to have a minimum of eighteen feet between crowns with the distance increasing with the percentage of slope.*
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Tree placement should be planned to ensure the mature canopy is no closer than ten feet to the edge of the structure.
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Tree and shrubs in this zone should be limited to small clusters of a few each to break up the continuity of the vegetation across the landscape.
Zone 3: The Extended Zone
The Extended Zone:
30-100 feet, out to 200 feet. Landscaping – the goal here is not to eliminate fire but to interrupt fire’s path and keep flames smaller and on the ground.
This house faces a significant risk if a nearby wildfire were to occur. The high amount of available fuel is a contributing factor.
Preventative Action:
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Dispose of heavy accumulations of ground litter/debris.
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Remove dead plant and tree material.
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Remove small conifers growing between mature trees.
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Remove vegetation adjacent to storage sheds or other outbuildings within this area.
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Trees 30 to 60 feet from the home should have at least 12 feet between canopy tops.
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Trees 60 to 100 feet from the home should have at least 6 feet between the canopy tops.
*The distances listed for crown spacing are suggested based on NFPA 1144. However, the crown spacing needed to reduce/prevent crown fire potential could be significantly greater due to slope, the species of trees involved and other site-specific conditions.
Sources:
National Fire Protection Association (NFPA): Preparing homes for wildfire
Federal Emergency Management Agency (FEMA): Creating a Defensible Space
Creating Defensible Space,
It's What We Do.
Be Proactive,
Not Reactive.
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