Interface Forestry logo, egg-shaped logo bordered by recycling arrows with ponderosa pine tree and roots

Interface Forestry

forest stewardship in the wildland-urban interface

Notes and Research

Wildfire Fuels Management

Creating Defensible Space and Managing the Home Ignition Zone

The object of hazardous fuel management is to create defensible space, wherein firefighters can assure public and personal safety while protecting structures and property from destruction or severe damage. Creating defensible space requires intensive assessment and fuel reduction in the area immediately around a residence -- within 100-200 feet. This area is the home ignition zone (HIZ). It also requires creating a safety zone and safe escape route for fire engine crews.

Defensibility is key to saving a house. A wildland fire crew will not attempt to defend an indefensible house. Personal safety is the firefighter's primary objective. During a major fire incident, incident response resources are scarce, so a form of triage is employed. No available amount of labor power and equipment will enable a crew to save an indefensible building, so no labor or equipment will be employed.

In the wildland-urban interface, homeowners face several responsibilities in protecting their houses and property from destruction or severe damage. The following list is NOT comprehensive but provides a good start:

  • Build with appropriate building materials and design. Any building constructed in forest areas should be built from fire-resistant materials and should have no exposed wood. Homes that burn during forest fires usually are not ignited directly from burning trees or crown fires, but rather, from fire-brands (floating embers) or fuels that ignite next to the houses, exposing them to direct flame.
  • Keep the area clear (as possible) of fuels -- flammable bushes (especially burners like juniper), piles of fire wood, building materials, wood chips, trees, lawn furniture, etc. Taking the needs of firefighters into consideration, some researches suggest a minimum of 200 feet distance from the building to any conceivable flame front. Others recommend clearing all shrubs and flammable plants within 30 feet of the structure and removing any tree that is within a distance twice the height of the tree. Thus, a 40-foot tall tree should be further than 80 feet from a combustible structure. This is a more flexible approach, but certainly depends upon a house designed to withstand a wildfire.
  • Maintain safe and accessible exit and entrance routes and plenty of turnaround places for emergency vehicles and residents. Escape routes and turnarounds should be clear of fuel to each side. (According to the National Wildfire Coordinating Council, escape routes should be protected by a 100-ft fuel break.)
  • Write a plan for identifying and isolating hazardous materials during a fire, including fuels, paints, chemicals, tires, oils, and other human-made materials. Include a map or drawing locating these materials as well as all propane tanks and lines.
  • Secure a readily available water source.
  • Make an address highly visible.
  • Acquire and maintain supplies and equipment for several tactics to protect a house during a flamefront, including but not limited to:
    • Installed or portable sprinkler systems (and gas pumps) for watering house and surrounding area.
    • Applied foam systems such as a Barricade Homekit or other foam systems and application equipment. These systems, if applied correctly, will protect a structure from fire brands and radiant heat for many hours, within limits. However, they are difficult to clean and raise the grain of wood.
  • Prepare an evacuation plan if you plan to evacuate during an incident.
  • If you plan to stay in the home during a fire, prepare a survival plan and assemble all necessary personal protection equipment, tools, water pumps, etc. After the flame front, prepare to take an active role in defending the house and buildings from ignition!

During a fire incident, the urban-interface landowner faces additional responsibilities in preparing for the flame front. The following list is NOT comprehensive but provides a good start:

  • Clear all fuels from around house (firewood, lawn furniture, plants, etc.).
  • Remove all propane tanks and fuels or insulate them from radiant heat and firebrands. If propane tanks must remain, turn off all valves.
  • Keep doors and windows closed but unlocked.
  • Cover all holes and openings on the roof or walls, as well as spaces under porches, stairs, and other possible entry routes for firebrands.
  • Dam rain gutters and fill them with water.
  • Position cars away from buildings (at least a distance 1-1/2 times as long as the highest point on the house). Park them facing the escape route.
  • Make tools available for firefighters to use.
  • If you plan to evacuate, do so hours before the expected flamefront. Most people who have died in an wildland-urban interface fire were attempting to escape too late into the incident.
  • If you plan to stay and protect the structure after the flame front, follow your survival plan. Do NOT attempt to escape shortly before the flamefront arrives. Most people who have died in an wildland-urban interface fire were attempting to escape too late into the incident.

Return to Top of Page

Managing Forestland Fuels

The primary goals that guide fuel reduction objectives are to reduce the risk of extensive tree mortality, given a wildfire, and to reduce the chance of a fire ascending from a surface fire to a crown or canopy fire. Under the best circumstances, treated stands can act like a firewall, forcing a crown fire back to the surface for lack of canopy fuel.

The primary method for reducing wildland fuels include thinning from below, preferably followed by periodic broadcast burning.

For larger holdings, we recommend a stand or forest plan.

A correctly treated stand will retain an aesthetic appeal and can often enhance aesthetic values (as well as property values). Any urban-interface fuel management will require continued effort over the years, but the initial treatment will be the most intensive.

Return to Top of Page


Arno, Stephen F., and James K. Brown, "Overcoming the Paradox in Managing Wildland Fire," Western Wildlands, Spring, 1991, 40-46,

Brown, James K., Elizabeth D. Reinhardt, and Kylie A. Kramer, Coarse Woody Debris: Managing Benefits and Fire Hazard in the Recovering Forest, Missoula, MT: Rocky Mountain Research Station, 2003). (RMRS-GTR-105.)

Cohen, Jack P., "A Site-Specific Approach for Assessing the Fire Risk to Structures at the Wildland/Urban Interface", Internet published.

Cohen, Jack D., "What is the Wildland Fire Threat to Homes?" Presented as the Thompson Memorial Lecture, April 10, 2000, School of Forestry, Northern Arizona University, Flagstaff, AZ.

Cohen, Jack D. "Preventing Disaster; Home Ignitability in the Wildland-Urban Interface," Journal of Forestry, 98(3), 2000, 15-21.

Cohen, Jack, "Wildland-Urban Fire -- a Different Approach," Proceedings of the Fire Safety Summit, Missoula, MT, November 7-9, 2001 (Missoula, MT: USDA, Forest Service, Rocky Mountain Research Station, 2001).

Firewise Communities, Assessing Wildfire Hazards in the Home Ignition Zone (Quincy, MA: National Fire Protection Association).

Graham, Russell T.; Sarah McCaffrey; Theresa B. Jain(tech. eds.), Science Basis for Changing Forest Structure to Modify Wildfire Behavior and Severity, (Ft. Collings, CO: USDA, Forest Service, Rocky Mountain Research Station, 2004).

Jain, Theresa B., "Is Forest Structure Related to Fire Severity? Yes, No, and Maybe: Methods and Insights in Quantifying the Answer," USDA Forest Service Proceedings(Moscow, ID: Rocky Mountain Research Station, 2004). (RMRS-P-34. 2004.)

Peterson, David L., Morris C. Johnson, James K. Agee, Theresea B. Jain, Donald McKenzie, and Elizabeth D. Reinhardt, Forest Structure and Fire Hazard in Dry Forests of the Western United States(Portland, OR: USDA, Forest Service, Pacific Northwest Research Station, 2005). (PNW-GTR-628. 2005.)

Peterson, David L., Morris C. Johnson, James K. Agee, Theresea B. Jain, Donald McKenzie, and Elizabeth D. Reinhardt, Fuels Planning: Managing Forest Structure to Reduce Fire Hazard, Online Publication.

Scott, Joe H. Fuel Reduction in Residential and Scenic Forests: a Comparison of Three Treatments in a Western Montana Ponderosa Pine Stand(Missoula, MT: USDA, Forest Service, Rocky Mountain Research Station, 1998). (RMRS-RP-5.)

Slaughter, Steve, Laura Ward, Mike Hillis, Jim Chew, and Rebecca McFarlan, "A Collaborative Fire Hazard Reduction/Ecosystem Restoration Stewardship Project in a Montana Mixed Ponderosa Pine/Douglas-fir/Western larch Wildland Urban Interface," USDA Forest Service Proceedings, 2004. (RMRS-P-35. 2004.)

Wilson, J.S. and P.J. Baker, "Mitigating Fire Risk to Late-Successional Forest Reserves on the East Slope of the Washington Cascade Range," Forest Ecology and Management 110, 1998, 59-75.

Links to related and supporting information

The Firewise Communities, USA, program is the best source of information on fuel management in the Home Ignition Zone.

Return to Top of Page