FAQ Defensible Space

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What is Defensible Space?

Defensible space refers to that area between a house and an oncoming wildfire where the vegetation has been modified to reduce the wildfire threat and to provide an opportunity for structural protection without rising homeowner or firefighter lives.  Sometimes a defensible space is simply a homeowner’s properly maintained backyard.

What is the Relationship Between Vegetation and Wildfire Threat?

Many people do not view the plants growing on their property as a threat.  But in terms of wildfire, what is growing adjacent to their homes can have considerable influence upon the survivability of their houses.  All vegetation, including naturally occurring native plants and ornamental plants in the residential landscape, is potential wildfire fuel.  If vegetation is properly modified and maintained, a wildfire can be slowed, the length of flames shortened, and the amount of heat reduced, all of which assist firefighters in defending the home against an oncoming wildfire.

The Fire Department is supposed to protect my house, so why bother with defensible space?

Some individuals incorrectly assume that a fire engine will be parked in their driveway and firefighters will be actively defending their home if a wildfire approaches.  During a major wildfire, it is unlikely there will be enough firefighting resources available to defend every home.  In these instances, firefighters will likely select homes they can safely and effectively protect.  Even with adequate resources, some wildfires may be so intense that there may be little that firefighters can do to prevent a house from burning.  The key is to reduce fire intensity as wildfire nears the house.  This can be accomplished by reducing the amount of flammable vegetation surrounding a home.  Consequently, the most important person in protecting a house from wildfire is not a firefighter, but the property owner.  And it’s the action taken by the owner before the wildfire occurs (such as proper landscaping) that is critical.

Does Defensible Space require a lot of bare ground in my landscape?

No.  Unfortunately, many people have this misconception.  While bare ground is certainly effective in reducing the wildfire threat, it is unnecessary and unacceptable due to appearance, soil erosion, and other reasons.  Many homes have attractive, well-vegetated properties that also serve as effective defensible space.

Does creating a Defensible space require any special skills or equipment?

No.  For the most part, creating a defensible space employs routine gardening and landscape maintenance practices, such as pruning, mowing, weeding, plant removal, appropriate plant selection, and irrigation.  The necessary equipment consists of common tools like a chain saw, pruning saw, pruning shears, loppers, weed-eater, shovel, and a rake.  A chipper, compost bin, or a large rented trash dumpster may be useful in disposing of unwanted plant material.

How big is an effective Defensible space?

Defensible space is usually expressed as the distance from the house in which vegetation is managed to reduce the wildfire threat.  The necessary distance for an effective defensible space is not the same for everyone, but varies by slope and type of wildland vegetation growing near the house.  (See the article entitled “Creating an Effective Defensible Space” for specific information.”)

Does Defensible space make a difference?

Yes.  Investigations of homes threatened by wildfire indicate that houses with an effective defensible space are much more likely to survive a wildfire.  Furthermore, homes with both an effective defensible space and a nonflammable roof (composition shingles, tile, metal, etc.) are many times more likely to survive a wildfire than those without defensible space and flammable roofs (wood shakes or shingles).  These conditions give firefighters the opportunity to effectively and safely defend the home.

Does having a Defensible Space guarantee my house will survive a wildfire?

No.  Under extreme conditions, almost any house can burn. But having a defensible space will significantly improve the odds of your home surviving a wildfire.

Why doesn’t everyone living in a high wildfire hazard area create a defensible space?

The specific reasons for not creating a defensible space are varied.  Some individuals believe “it won’t happen to me.”  Others think the costs (time, money, effort, loss of privacy, etc.) outweigh the benefits.  But some have failed to implement defensible space practices because of lack of knowledge or misconceptions.