Learning The Zones, Why They're important

The primary goal of defensible space is fuel reduction and hazard mitigation. - Limiting the amount of flammable vegetation and materials surrounding the home. The home and everything around it up to 100-200 feet are known as the 'home ignition zone. In areas across the country where the risk of wildfire is high, the home ignition zone extends up to 200 feet beyond the actual structure. Within this 200-foot area, there are three zones:

ZONE ONE:  0 - 30 ft. -This zone encircles the structure and all its attachments (wooden decks, fences, attached sheds, etc.) for at least 30 feet on all sides. Note: the 30 ft. number comes from the very minimum distance. On flat ground, a wood wall can be separated from the radiant heat of large flames without igniting. In this zone:

  • Plants should be carefully spaced, low growing, and free of resins, oils, and waxes that burn or  ignite easily
  •  Mow the lawn regularly
  •  Remove weeds regularly
  •  Prune trees up six to ten feet from the ground
  •  Space conifer trees 30 feet between crowns
  •  Trim overhanging limbs from the roof
  •  Create a 'fire-free' area within 5 feet of the home, using non-flammable landscaping
  •  Remove dead or living vegetation from under the deck and within 10 feet of the house
  •  Consider fire-resistant materials for outside furniture
  •  Remove firewood stacks and propane tanks
  •  Use firewise landscaping around this zone (gravel, rocks, pavers, etc.)
  •  Remove pine needles and leaves from rooftops and gutters
  • Remove flammable chemicals from around the structure (gas cans, paint cans, automotive products, etc.

ZONE TWO: 30 -100 ft. -This area around the home should be well thinned and maintained, low growing, well irrigated, and less flammable. In our AZ fuel model (mostly brush and some mixed chaparral), these need to be reduced considerably. Flame lengths from these can reach three times the plant height and put out extreme radiant heat.  In this zone:

  • Leave 30 feet between clusters of two to three trees or brush, or 20 feet between individual trees
  • Encourage a mixture of deciduous and coniferous trees
  • Create 'fuel breaks,' like driveways, gravel walkways, and lawns
  • Prune trees up six to ten feet from the ground
  • Remove all 'dead and downed' trees from under and around trees and brush that are to be left

ZONE THREE: 100 - 250 ft. -This area should be adequately thinned, although less space is required than in Zone 2. Note: Because of other factors such as topography, the recommended distances to mitigate radiant heat exposure extend between 100 - 200 feet from the home - this would be on a site-specific basis.  In this zone:

  • Remove smaller conifers that are growing between taller trees
  • Remove all 'dead and down trees and brush
  • Reduce the density of tall trees, so canopies are not touching
  • Reduce or remove fuels on property boundaries to reduce property to property ignition