30 to 100 Feet: The Extended Zone

The goal for the Extended Zone is not to eliminate fire but to interrupt fire’s path and keep flames smaller and on the ground. In order to protect your home from wildfire, in the extended zone you should:

  • Dispose of heavy accumulations of ground litter and debris.
  • Remove dead plant and tree material. 
  • Remove vegetation adjacent to storage sheds or other outbuildings within this area.
  • Remove small conifers growing between mature trees.
  • Have thin understory brush, especially under the canopy of any conifer trees. If there are no trees, thin around the largest species of brush and prune away lower limbs and dead wood (e.g. large manzanita shrubs).
  • Remove ladder fuels (vegetation under trees) so a surface fire cannot reach the crowns. Prune trees at least six (6) to ten (10) feet from the ground. For trees under 18 feet tall, do not exceed pruning up 1/3 of the overall tree height.
    • The lowest limbs of trees should clear any vegetation underneath the tree by at least three times the height of the undergrowth, or be removed, for effective risk reduction.
  • Adequately space highly combustible trees and shrubbery to prevent interlocking canopies at maturity. Consult with an arborist or forester if you are unsure which species are best for your property. 
  • Isolate Islands of more dense trees or native brush from surrounding vegetation.
  • Thin brush and limb trees within 30 feet of your driveway on each side, especially if it is more than 100 feet long. Increase the distance on the downhill side if the driveway crosses a slope.
  • Establish and maintain at least 13.5 feet of clearance above the road surface for fire vehicles to pass under tree limbs.
  • Clear vegetation and tree litter from under large stationary propane tanks. Maintain a 10-foot clearance from dry vegetation around these tanks at all times.
  • Trees (or small groupings of trees) 30 to 60 feet from the home should have at least 12 feet of space between canopies*; increase that distance if on a slope.
  • Trees (or small groupings of trees) 60 to 100 feet from the home should have at least 6 feet of space between canopies*; increase that distance if on a slope.

*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. Check with your local forestry professional to get advice on what is appropriate for your property.