September is National Preparedness Month, something we here at Mountain House take very seriously—and you should too! The theme for this year’s Preparedness Month is: “Disasters Happen. Prepare Now. Learn How.” Disaster preparation and emergency response are topics we regularly cover here at the Mountain House blog, and as part of fulfilling that National Preparedness Month theme we urge you to explore our “Survival” archives. Our focus in this article is on wildfire safety, with helpful information on how we can mitigate losses by utilizing defensible space tactics.
Wildfires are among the most widespread and destructive natural disasters in the United States, though it’s important to emphasize that (with the exception perhaps of human-caused blazes) they’re also natural and necessary elements of most of our country’s ecosystems. In 2017, according to the National Interagency Fire Center, more than 71,000 wildfires burned better than 10 million acres in the USA. This year has been yet another intense one in the wildfire department, and many blazes are still burning. No better time than National Preparedness Month to bone up on wildfire safety—especially given September is the height of wildfire season in many parts of the country.
We previously published a general overview on how to prepare for wildfires that we urge you to review. Today we’d like to narrow our focus to one of the most important elements of that preparation: maintaining defensible space around your home to reduce the likelihood it’ll ignite in a wildfire. This is especially relevant to those who live in the wildland-urban interface, where residential homes abut (or are immersed within) landscapes prone to wildfire; for the past several decades, a majority of the new homes built in the USA are within this risky (and typically beautiful) realm.
Defensible space refers to a buffer zone around your home in which you actively manage vegetation and other landscape elements to reduce all-around flammability. It’s about fire-safe landscaping: firescaping, as it’s called.
Defensible space is related to the concept of the Home Ignition Zone, or HIZ, which a retired USDA Forest Service scientist, Jack Cohen, defined back in the late ‘90s. Based on post-fire analysis, modeling, and experiments on how buildings ignite in wildfires, the HIZ encompasses everything within 200 feet of your home.
That 200-foot HIZ area comes broken up into three sub-zones based on proximity to the home exterior:
As the National Fire Protection Association explains, you should begin focusing on the Immediate Zone, as the house is what’s most vulnerable to catching flame by embers. Then move out to the hardscaping and landscaping of the Intermediate and Extended zones.
You’ll also see references to two zones of defensible space in firescaping discussions. Zone 1 of defensible space extends out 30 feet from your house and any other structures, basically corresponding with the Immediate and Intermediate zones of the HIZ. Zone 2 of defensible space lies 30 feet and more out, associated with the HIZ Extended Zone. Keep in mind that your defensible space increases if your property is on sloping terrain; fire can spread more easily on slopes because flames can more efficiently pre-heat upslope fuel, and because of natural upslope and downslope breezes.
It's always important to consult wildfire-preparation and prevention resources specific to your area (for example, from a state forestry or extension service), because fire regimes vary wildly from ecosystem to ecosystem and from wildland-urban interface to wildland-urban interface.
Any plant can burn given the right condition: You're not going to find truly “fireproof” vegetation for your landscaping. What you can plant is fire-resistantvegetation, and in the sort of configuration that lessens the likelihood of carrying flame. Plants with low concentrations of sap and resin and high water storage are the best choices. Succulent groundcover herbs and shrublets in a mosaic with hardscaping help reduce fire risk. Keep flowerbeds isolated from one another with hardscaping or mowed grass. Favor non-resinous shrubs and keep them well spaced out.
Besides our "How to Prepare for a Wildfire" blogpost, we recommend the following references for more detailed information on sensibly managing your defensible space:
And for general National Preparedness Month resources, head on over to Ready.gov!