Home Hardening 101: Defensible Space

If you live in a wildfire risk area such as Big Sky, Montana, it is crucial you create a proactive approach to wildfire preparedness not only to preserve your home, but also for the safety of you, your family, and your community. For today’s lesson on home hardening, we will focus on defensible space, which not only acts as a barrier to slow or halt the progress of a wildfire, but also helps ensure the safety of firefighters defending your home and community.

What Is Defensible Space?

One of the primary determinants of a home’s ability to survive a wildfire is the quality of the surrounding defensible space of your home. Defensible space is the area around a home or other structure that has been modified to reduce fire hazards. In this area, natural and manmade fuels are treated, cleared, or reduced to slow the spread of wildfire. Establishing defensible space reduces the likelihood of a home igniting by direct contact with flame, blown embers, or by exposure to the radiant heat of the fire. It also helps limit local production of embers and reduces the chance a structure fire will spread to neighboring homes or surrounding vegetation. Creating an effective defensible space involves establishing a series of management zones.

Defensible Space Zones

Zone 1: 0-5 Feet from the Home

Zone 1 is defined as the area which is zero to five feet away from your home and is the most critical for fire protection. You should have nothing flammable next to the house, including tall grass, evergreen trees and shrubs, trees that overhang the house or deck, leaves, brush, firewood piles, bark, mulch and other burnables. Additionally gutters, roof surfaces, and decks should be cleaned of all flammable debris.

Zone 1 Tips
  • Use hardscape like gravel, pavers, or concrete. No combustible bark or mulch.
  •  Remove all dead and dying plants, weeds, and debris (leaves, needles, etc.) from your roof, gutter, deck, porch, stairways, and under any areas of your home.
  • Remove all branches within 10 feet of any chimney or stovepipe outlet.
  • Limit combustible items (like outdoor furniture and planters) on top of decks.
  • Relocate firewood and lumber to Zone 3.
  • Replace combustible fencing, gates, and arbors attached to the home with noncombustible alternatives.
  • Consider relocating garbage and recycling containers outside this zone.

Zone 2: 5-30 Feet from the Home

Zone 2 is defined as the area which is five to thirty feet away from your home. In this fuel reduction zone, remove flammable vegetation, with the goal of reducing the amount of fuel available for a wildfire. This involves removing trees and other vegetation that are within this area as well as trimming or pruning trees and shrubs. In some cases, it may also be necessary to clear a wider area around the building to create a buffer of non-flammable material.

Zone 2 Tips
    • Cut annual grasses and forbs to maintain a Maximum 4” height.
    • Make separation to meet continuous canopy separation.
    • Selective timber thinning.
    • Remove later fuels.
    • Remove woody surface fuels and condensed aerial fuels will be removed.
    • Isolate stumps from other vegetation sources (low cut stumps).
    • Remove downed dead logs and wood debris.
    • Remove loose surface litter (twigs, bark, cones, and small branches)

Zone 3: 30-100 Feet from the Home

Zone 3, also known as the access zone, is defined as the area which is thirty to one hundred feet away from your home. This area should be maintained to provide access for firefighters and other emergency responders to use roads while going to and from your house in the event of a fire. In this zone it is recommended to rake or use a leaf blower to remove leaves and twigs at least 30 feet from the house and up to 100 feet on the downhill side. Prune and thin trees so there are no dense stands or tree tops touching. Keep shrubs small, maintained, and free of dead materials. Control brush and weeds annually. Steep areas can be terraced to slow down wildfires. A stone wall can also act as a fire barrier on very steep slopes.

Zone 3 Tips
  • Cut or mow annual grass down to a maximum height of four inches.
  • Create horizontal space between shrubs and trees.
  • Remove later fuels to 14’ when over any roadway.
  • Isolate stumps from other vegetation sources (low cut stumps).
  • Scrap to bare mineral (where appropriate).
  • Remove debris, dead material.



Defensible space is not only beneficial for individual properties but also for the overall community. By consistently implementing these practices across a neighborhood or region, the collective efforts can create a fire-resilient community, reducing the risk of large-scale wildfires and safeguarding multiple properties simultaneously.

For more information on defensible space, please reach out to Cornerstone Management Services today.



Written by: 

Paul Williamson — Director of Business Development




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