DEFENSIBLE SPACE ZONES

Defensible space is an area around the structures where fuels and vegetation are treated, cleared or reduced to slow the spread of wildfire towards the structure. It also reduces the chances of structure fire moving from the building to surrounding vegetation.   Defensible space provides room for firefighters to do their jobs. Your house is likely to withstand a wildfire if vegetation is managed to reduce a fire's intensity.

Creating defensible space involves developing a series of management zones in which different treatment methods are used.

Fire can find the weak link in your home's fire protection scheme and gain the upper hand because of a seemingly inconsequential factor. Begin your work closest to your home and move outward. Keep working until your entire project is completed.

Zone 1

The size of this zone is 30 feet around the structure in which flammable vegetation is most heavily managed. It is measured from the outside edge of the home's eaves or any attached structures, such as decks. If you leave a tree in this zone, consider it part of the structure and extend the space accordingly. Within this 30 foot zone the first 10 feet is the most crucial. No vegetation should be touching the structure.

If the house has noncombustible siding, widely spaced foundation planting of low growing shrubs or other "fire wise" plants are acceptable. Do not plant directly beneath windows or next to foundation vents. Be sure there are no areas of continuous grass adjacent to plantings in this area.

Use firewise plants.

Frequently prune and maintain plants.

Trim trees and shrubs so there is a 10’ spacing between crown.

Mow grasses to a maximum of 4 inches.

Remove all dead branches, stems, leaves, needles, etc.

Do not use area under deck for stor age.

No firewood should be stacked in this area.

Zone 2

In this area the reduction of fuel is designed to reduce the intensity of any fire approaching your home. It is typically 30 to 60 feet from the structure but depends on the slope of the ground where the structure is built. Propane tanks may be located within this area.

Remove stressed, diseased, dead or dying trees and shrubs. Thin and prune remaining large trees and shrubs. Be sure to extend thinning along either side of the driveway to the main access road.

This zone forms an aesthetic buffer. It will help eliminate the fuel surrounding the structure while it enhances the home site safety and aesthetics of the property.

Trim trees and shrubs so there is a 10 foot space between crowns.

On steep slopes allow more space between crowns.

Prune trees to at least 8 feet above ground.

Remove all ladder fuels beneath trees.

Remove dead trees and snags within this area.

Mow grasses to a maximum of 6 to 8 inches, especially in the fall.

Stack firewood uphill or on same elevation as structure.

Locate propane tank at least 30 feet from structures.

Clear and keep vegetation 10 feet from propane tank.

Remove all dead brush.

Zone 3

This is an area of native vegetation extending from 60 to 90 feet from the Structure being protected. This zone should maintain healthy and vigorous trees; provide barriers for wind, noise, dust and visual intrusion while enhancing aesthetics.

Specific requirements will be dictated by vegetation on the property.

Minimize ground fuels.

Remove trees that are damaged, attacked by insects or diseased.

Make sure any snag trees pose no threat to power lines or roads.

Thin evergreens to enhance tree health.

Tree Spacing rule of Thumb

Ponderosa Pine and Douglas Fir – Substitute stem diameter in inches to feet and add 7 feet.

Lodgepose and Engelmann Spruce – Substitute stem diameter in inches to feet and add 5 feet.

Example: A Ponderosa pine 8” in diameter at breast height (dbh); change 8 inches to 8 feet and add 7 feet equaling 15 feet between stems.

Firewise Checklist

Properly thin and prune trees and shrubs within the defensible space.

Gutters and roof cleared of debris

Fire-resistant roof.

All branches overhanging roof and chimneys are removed.

Chimney screens or caps are in place.

Outdoor water supply is available, complete with a hose and nozzle that can reach all parts of the house.

Fire extinguishers are checked and in good working order.

House number and/or name posted and legible 6" numbers from the road.

Decks treated with retardant.

Eaves enclosed, vents screened.

Place propane tank at lease 30 feet from structures.

Store firewood at lease 30 feet from structures or trees.

Make sure driveways and roads are wide enough for emergency equipment.

Enclose stilt foundations; screen in or enclosed elevated decks.

Trash and debris accumulations are removed from the defensible space.

Nonflammable siding and fencing.

Grasses and weeds mowed to a low height. (6"-8")