Wildfire and urban wildfire are an ongoing concern for Boulder County and the state of Colorado. Generally, the fire season extends from spring to late fall. Fire conditions arise from a combination of hot weather, an accumulation of vegetation, and low moisture content in air and fuel. These conditions, especially when combined with high winds and years of drought, increase the potential for wildfire. Wildfire is a particular risk in the wildland-urban interface areas, where more people are choosing to build homes, operate businesses and recreate along the borders of urban development. A fire along this wildland-urban interface can result in major losses of property and homes.

Two factors have emerged as determinants of how well a home will be able to survive wildfire; the home’s roofing material and quality of ‘defensible space’ around the home.


Roofing Material

  • Use fire-resistant materials (class C or better rating), not wood or shake shingles to roof homes.
  • When repairing or replacing your roof, use fire-resistant materials (as above).
  • Check with your county building division. Some counties now restrict wood roofs or require specific classifications of roofing material.


Defensible Space

Defensible space is the area around a structure where fuels and vegetation are treated, cleared or reduced to slow the spread of wildfire towards the structure. Creating an effective defensible space involves developing a series of management zones in which different techniques are used.  As a mountain property owner, your first defense against wildfire is to create and maintain a defensible space around each building on your property.

Zone 1 - The Safety Zone

This area is where you will do the most modification and treatment. It consists of an area of 15 -30 feet around the structure, in which all flammable vegetation is removed. This 15 - 30 feet is measured from the outside edge of the home’s eaves and any attached structures, such as decks. Within this zone, several specific treatments are recommended:

  • Plant nothing within three to five feet of the structure, particularly if the building is sided with a flammable material. Opt for weed barrier covered with rock or gravel instead.
  • Make sure there are no areas of continuous grass adjacent to plantings in this area and frequently prune plants in this zone to ensure vigorous but low growth. Keep grasses mowed to four to six inches.
  • Remove dead branches, stems and leaves.
  • Enclose or screen decks with metal screening and extend gravel coverage under the decks. Do not use the area under decks for storage of anything that will burn.
  • Do not store firewood in this area, particularly in sheds built onto the structure.
  • Keep gutters and roofs clear of leaves, pine needles and debris.
  • Remove all trees from this zone, or if you keep trees, consider them part of the structure and extend the distance of the defensible space accordingly. Isolate trees from each other, prune to at least 10 feet above ground, and remove branches within 10 feet of any chimney.
  • Remove all ‘ladder fuels’ from beneath the trees. Ladder fuels are small shrubs, trees, limbs and other materials that allow a fire to climb on the tree crown of branches and foliage.

Zone 2 - The Transition Zone

This is an area of fuel reduction and a transitional area between Zones 1 and 3. The size of Zone 2 will vary depending on the slope of the ground where the structure is built. The defensible space should extend from a minimum of 75 feet, to 125 feet or more from the structure. Within this zone, the arrangement of vegetation (fuel) should be modified.

  • Remove stressed, diseased, dead or dying trees and shrubs.
  • Thin and prune the trees and large shrubs in this zone so that there is at least 10 feet of distance between the crowns (see Figure 2).
  • Extend thinning along both sides of your driveway all the way to your main access road. This will help eliminate the continuous fuel surrounding a structure and also enhance home safety and the aesthetics of the property.
  • Blend the treatment of Zones 1 and 3 by gradually decreasing the thinning of trees as you near the outer part of Zone 2.
  • Mow or cut down grasses through the growing season to keep them no higher than six to eight inches. This is especially important in the fall when grasses dry out and after the spring thaw, when snow is gone, but before plants get green.
  • Stack firewood uphill or at the same elevation as the structure, but at least 30 feet away. Keep flammable vegetation at least 10 feet away. Propane tanks are treated the same, but ideally should be a the same elevation as the structure – if they are placed below, a burning tank will burn uphill toward your home; if placed above, leaking propane could impact your home when it flows downhill.
  • Dispose of slash and other dead vegetation by chipping, piling and burning. noTe: Most counties have strict regulations about when and how to conduct controlled burning. Contact the Boulder County Environmental Health Department before you burn at 303-441-1100. In Boulder County, the Boulder County Sheriff’s Communications Center also needs to know when you will be burning. Contact them at 303-441-4444.

Zone 3 - The Management Zone

This is an area of traditional forest management and is of no particular size. It extends from the edge of your defensible space to your property boundaries. In this area, you are encouraged to manage your forests in a more traditional manner. The actions you take will be determined by your objectives for your property. At minimum, you may want to:

  • Remove trees that are diseased, insect-infested, and those of poor form or low vigor.
  • Thin trees for forest health.

These actions will sanitize and improve the health of the forest on your land. If you choose to do methodical thinning in Zone 3, contact the Boulder County Wildfire Mitigation Coordinator for specific guidelines andadvice at (720) 564-2625.

Outdoor Recreation Fire Safety

Be aware of fire risks and take responsibility for your use of fire.

  • Before you leave home, check with authorities at your camping location for fire restrictions. During especially dry seasons, even recreational and cooking fires can be restricted.
  • Be careful with campfires - only build fires in rings or grates. Avoid areas with overhanging branches, steep slopes and dry grasses.
  • Maintain a safety zone around a campfire and always closely supervise children. Teach them to stop, drop and roll if their clothing catches on fire.
  • Keep a bucket of water and shovel nearby to put out the fire. When extinguishing a campfire, drown it with water and stir with water and dirt until all the ashes are cold.
  • Use self-contained cookers or chemical stoves instead of campfires for cooking.
  • Keep hot mufflers and catalytic converters clear of grasses and shrubs.
  • Think about how you would evacuate in the event of a wildfire. Plan the routes you could take, including at least one alternate route, in case yourprimary route is blocked.
  • If you see smoke or a fire, call 911.