Basics of Defensible Space and the “Home Ignition Zone”

The Forest Service developed the concept of the home ignition zone (at least 30 but up to 200 feet) in the late 1990s, following experimental research into how homes ignite due to the effects of radiant heat.

Wildfire safety recommendations have been shaped by this fire science and because of it the Forest Service is able to provide guidance for wildfire mitigation using Firewise landscaping ideas. 
Embers and small fires are the major reason homes ignite in wildfires. Wind-blown fire embers (embers can be fist/pinecone size) can travel one mile or more. Protecting your home and property from wildfire is YOUR responsibility. Don't assume firefighters can save your home or property. As much as they may want to, resources are limited and conditions may make it impossible to safely reach and protect your home. You can take steps to mitigate the fire danger to your home through Firewise landscaping.

The primary goal of Firewise landscaping is fuel reduction – limiting the amount of flammable vegetation and materials surrounding the home and increasing the moisture content of the remaining vegetation. Create a defensible space around your home and the major structures on your property by reducing the vegetation surrounding the structures. This does not mean that your landscape has to be barren. Defensible space is an area where the vegetation is modified to slow the rate of spread and intensity of an advancing wildfire. This space also provides room for the firefighters to work and protect the forest should a structure fire occur.

Plants should be carefully spaced, low growing and free of resins, oils and waxes that burn easily. High resin plants include pine and juniper.
  • Mow the lawn regularly. Prune trees up six to ten feet from the ground.
  • Space conifer trees 30 feet between crowns. Trim back trees that overhang the house.
  • Create a ‘fire-free’ area within five feet of the home, using non-flammable landscaping materials and/or high-moisture-content annuals and perennials.
  • Remove dead vegetation from under deck and within 10 feet of house.
  • Consider fire-resistant material for patio furniture, swing sets, etc.
  • Remove firewood stacks and propane tanks.
  • Water plants, trees and mulch regularly.
  • Consider xeriscaping if you are affected by water-use restrictions.
  • Clear needles, leaves and other debris from the roof, gutters, eaves, porches and decks. This prevents embers from igniting your home.
Note: The 30 foot ignition zone number comes from the very minimum distance on flat ground that a wood wall can be separated from the radiant heat of large flames without igniting.

If you know the relative location of your property, you can check its CSFD Wildfire Risk Rating (per their 2018 survey) here.  You can check the Wildfire Risk Rating for your specific property address at this site.

Fire Mitigating Oak

Some types of oak trees are fire resistant…not the Gambel Oak found in our area. Remove oak to keep it away from the house. Oak can act as a “ladder fuel,” with fire climbing from oak to the pines or house. The perimeter of the home out to about five feet is vulnerable if there is anything there – organic mulch, woody shrubs (oaks) and other plants that could ignite and thus allow flames to touch the house. Thinning and clearing dead material away from oak that is away from the house allows the remaining plants to become healthier and more resistant to drought and hence, more fire resistant.

For more information, see the Colorado State Forest Service Publication 6.311 on Gambel Oak.
Do the “little things” first

It is hard to know where to start so the Forest Service suggests the following:
  • Keep roofs and gutters clean and clear of leaves or needles - this is critical to minimizing ignition from embers. 
  • Flammable attachments (e.g., untreated wooden decks) are very vulnerable to ignition and can carry fire to the main structure. 
  • Keep flat surfaces clear of debris. 
  • Clean out from under decks or porches any leaves, needles or stored material that could burn. 
  • During high fire danger season, remove large potential heat sources such as piles of firewood, spare building materials, vehicles - anything that could catch embers or ignite by flames in the grass needs to be as far away from dwellings as possible.
There is a wealth of information about fire mitigation on the Internet. The suggestions above are just the bare minimum of available data. For further information regarding defensible space visit 

Colorado Springs Fire Department

The Colorado Springs Fire Department (CSFD) has a free inspection program for homeowners. If you would like specific fire mitigation recommendations about your home the CSFD will send out a fireman from their fire mitigation unit. The telephone number for the Fire Department Wildfire Mitigation department is 719 385-7342