Spring is the time to implement defensible space and home hardening

LAKE TAHOE, Calif./Nev. – As we move into the warm season, it’s time to start thinking about defensible space and home hardening. The choice Tahoe residents make to live in the forest surrounding beautiful Lake Tahoe comes with added responsibility. This responsibility includes minimizing the risk of wildfire from embers landing on or around your home or property. Research suggests that 60-90 percent of home ignitions are due to embers falling on something combustible such as pine needles, leaves, juniper bushes, and/or patio furniture. Once ignited, ember fires eagerly search for nearby combustible material (fuels) and once found produce more embers, creating a destructive cycle.

Wildfire risk is reduced in areas where defensible space and home hardening tasks are completed. Whether it is a wildland fire or a nearby structure fire, embers are the problem. Fire embers are weightless and easily carried by the wind, which allows them to land on combustible material, creating new fire ignitions. Embers can sometimes travel a mile or more away from the flame front. This is the most common cause of structure ignition during wildland fire events.

Defensible space is a strategic approach that helps minimize and space out vegetation and keeps yards clean and free of debris. When defensible space is implemented properly, there is a greater chance the home will survive during a wildfire. Fire department response is generally designed to be able to protect one structure at a time, albeit they readily adapt to every scenario. The industry standard is 15-17 fire personnel on scene to efficiently fight a structure fire1. If multiple structures are burning, fire department resources can quickly become overwhelmed, and firefighters must triage structures to determine those most likely to survive and focus on those.

Home hardening is a term used to describe using non-combustible building materials in combination with defensible space to reduce the intrusion of flames or embers created by wildland or structure fires. Home Hardening utilizes fire-resistant building materials including shingles, siding, decks, windows, fences, and more, and can be applied to new construction or when retrofitting older homes. Visit CAL FIRE’s webpage on Home Hardening for more information.

By implementing defensible space and home hardening, you are doing your part to keep Tahoe more fire-resistant and reduce risk that draws on local resources. You are also optimizing the best potential outcome for your home. The minimum defensible space standard is broken down into the following zones.

Zone 0 - Nothing combustible within 5 feet of structures
Zone 1 - Within 30 feet of all structures or to the property line
Zone 2 - Within 30-100 feet of all structures or to the property line
Defensible and Reduced Fuel Zone - Within 100 feet of all structures or the property line

For each zone, the defensible space standard recommends the following:

1. Removing all branches within 10 feet of any chimney or stovepipe outlet. The concern is embers coming from the chimney may ignite tree limbs.
2. Removing leaves, needles or other vegetation on roofs, gutters, decks, porches, stairways, etc. Dead vegetation is highly flammable and can easily ignite.
3. Removing all dead and dying trees, branches and shrubs, or other plants adjacent to or overhanging buildings.
4. Removing all dead and dying grass, plants, shrubs, trees, branches, leaves, weeds, and needles.
5. Removing or separating live flammable ground cover and shrubs. Ladder fuels are low-level vegetation that reaches upward and can carry fire to taller vegetation.
6. Removing flammable vegetation and items that could catch fire and are adjacent to, or below, combustible decks, balconies, and stairs. Embers tend to swirl in nooks and crannies such as under decks, soffits, or balconies. Anything combustible in this area is susceptible to fire.
7. Relocating exposed wood piles outside of Zone 1 unless completely covered in a fire-resistant material. Wood piles should be kept 30 feet from the structure or further. If the property line is less than 30 feet from the structure, the next best option is to cover the wood pile with a fire-resistant tarp. These can be found online or at local hardware stores. Ensure the tarp is tucked under to avoid embers finding their way in.
8. Cutting annual grasses and forbs down to a maximum height of 4 inches. All vegetation is flammable.
9. Removing fuels in accordance with the Fuel Separation or Continuous Tree Canopy guidelines. Continuous canopies allow fire to spread from treetop to treetop, creating greater ember cast.
10. All exposed woodpiles must have a minimum of 10 feet clearance, down to mineral soil, in all directions. Wood piles are a major source of fuel that can produce significant flames and embers.
11. Dead and dying woody surface fuels and aerial fuels should be removed. Loose surface litter, normally consisting of fallen leaves or needles, twigs, bark, cones, and small branches, are permitted to a maximum depth of three inches. Dead vegetation is very dry and can ignite easily.
12. Logs or stumps embedded in the soil must be removed or isolated from other vegetation. These are a fuel source that can produce large flames and ember cast.
13. Outbuildings and Liquid Propane Gas (LPG) storage tanks should have 10 feet of clearance to bare mineral soil and no flammable vegetation for an additional 10 feet around the exterior. Propane can boil within its container and produce an explosion if heated enough. It is important to ensure heat sources are not available to create this scenario.
14. Address numbers on homes should be displayed in contrasting colors (4-inch minimum size) and readable from the street or access road. This is to ensure 911 response can locate the structure.
15. Equip chimney or stovepipe openings with metal screens that have openings between three-eighths of an inch and one-half inch. This minimizes the chance that embers will escape the chimney.

These are the minimum defensible space standards. There are additional actions that are scientifically proven to make a difference. The most important zone is Zone 0 which is a newer concept since the above standards were developed and proven to be effective through extensive research and testing2. Having anything combustible within 5 feet of your home (including a hot tub), provides a potential ignition source. If Zone 0 is clear of flammable items, there is a reduced chance that something will ignite and transfer fire to the structure.

Defensible space and home hardening also complement fuels reduction and forest thinning projects implemented by land management agencies near communities and neighborhoods. View an interactive map that features completed forest fuels treatments for the Tahoe Basin.

Fire agencies around the lake are engaged and happy to help inform residents on the necessary steps for implementing defensible space and home hardening. Many districts also offer free chipping services. For questions and to find your local fire department or district, visit the Tahoe Living With Fire Find Your District webpage. The Tahoe Living With Fire website also offers phenomenal resources to help you Get Informed, Get Prepared, and Get Involved this spring!