The concept of the home ignition zone was developed by retired USDA Forest Service fire scientist Jack Cohen in the late 1990s, following some breakthrough experimental research into how homes ignite due to the effects of radiant heat. The HIZ is divided into three zones.

The ember-resistant zone is currently not required by law, but science has proven it to be the most important of all the defensible space zones.  This zone includes the area under and around all attached decks and requires the most stringent wildfire fuel reduction.  The ember-resistant zone is designed to keep fire or embers from igniting materials that can spread the fire to your home.

Defensible space is the required 100 feet between your property and the surrounding area.

Vent openings are vulnerable spots for ember entry into the home. Many vents use wire mesh coverings. Some building codes set the minimum mesh size for these at 1/4 inch. Smaller mesh sizes can become clogged by paint, cobwebs, debris, etc. that will reduce airflow. Unfortunately, the 1/4-inch mesh is ineffective in preventing ember entry into the attic, eave, and crawl space vents. For existing…

A house with a wood shake roof and siding is often more likely to be destroyed during a wildfire. Using wood shakes or shingles for exterior materials in high fire hazard areas is like stacking hundreds of pounds of kindling on top of your home.

Most people believe that wildfires ignite homes through direct contact with flames, but it is rare to have a home ignite this way. Flaming brands and embers can travel a mile or more ahead of the active front of a wildfire, and up to 60 percent of wildland urban interface home ignitions result from embers.