Wildfire Safety: Using Defensible Space to Protect Your Home

Maintenance is an ongoing process. Something as seemingly innocent as a forgotten basket of clippings that have dried out in the sun or wheelbarrow of firewood left too close to the house can turn into a deadly ignition source in seconds.

Upwards of a quarter of the homes built in the WUI are second homes. If yours is one of them and you don’t have someone regularly doing maintenance, err on the side of too much defensible space, and make your ignition zone as maintenance-free and spark-proof as you possibly can.

Zone One: 0 to 30 Feet (for all homes in the WUI)

Zone One is typically defined as 30 feet in all directions from your house and any attached structures such as decks, garages and storage buildings, as well as any trees next to the house you are incorporating into your defensible space. Experts recommend that everyone in the WUI create a Firewise Zone 1 regardless of your hazard-area rating.

Fire-Free Five. Make a minimum of the first five feet surrounding your house free of anything flammable. Use fire-resistant landscaping materials such as rock mulch (bark and chip mulch become flammable when dry) or stone walkways, or plant high moisture content annuals or perennials.

Five to 30 feet.  Choose plants that are low growing and don’t contain waxes, resins, and oils that burn easily. Group and space plantings so they don’t create a continuous path for the fire.

•Trim tree branches that overhang the house.
•Trim trees branch up 6 to 10 feet from the ground; this prevents the lower branches from serving as ladders for the fire to climb.
• Space conifer trees so there is 30 feet between crowns. If you plan to cut down trees around your home to improve your defensible space choose wisely: conifers, pines, evergreens, firs, and eucalyptus will catch on fire faster than hardwood trees. 
•Keep your grass watered and mowed. A well-watered lawn can serve as a fire break. A dry, overgrown lawn can serve as a fire path. If you live in an arid climate or have to deal with frequent water restrictions, consider xeriscaping with rock and fire-resistant, drought-tolerant plants and groundcovers.
• Remove any dead vegetation from under decks and within ten feet of the house. Once you’ve screened in the space below your deck, you’ll have an easier time keeping blowing leaves and debris out. But it will probably still pile up when the wind blows, so make a habit of walking your perimeter regularly during fire season. 
• Locate propane tanks and woodpiles outside this zone.

Zone Two: 30 to 100 Feet (for Moderate and High Hazard Areas)

• Use plantings that are low-growing, well-irrigated and less flammable.
• Trees should be clustered in groups of two or three with 30 feet between clusters; leave 20 feet between individual trees.
• Prune lower branches up 6 to 10 feet from the ground.
• Encourage a mix of deciduous and coniferous trees if your climate permits.
• Create fire breaks with walkways, lawns, water features, rock gardens, rock patios, and gravel or paved driveways.

Zone Three:  100 to 200 Feet (for High Hazard Areas)

Reduce density in this area by thinning and creating more space between trees. Prune tall trees so the crowns (tops) don’t touch. Remove small conifers growing in between larger trees—they provide ladder fuel.

If you have several acres or more, you might want to consult a forester about the smartest way to thin. Some studies show that thinning for thinning’s sake can make it easier for a surface fire to spread. The best approach is to execute a plan that takes typical fire behavior during dry and windy conditions into account rather than just thin to an arbitrary density.

What To Do with Slash Piles

Mounds of tree branches and debris are the inevitable result of thinning or removing dead or diseased trees. Slash piles can turn into gigantic fire-feeding bonfires if a wildfire sweeps through, so before you start cutting, figure out what you’re going to do with your slash. Some communities have chipping programs, where you can take slash to a central collection site. Some landfills and recycling yards accept slash. You can buy a chipper that will take care of small and medium-sized branches. And in many places you can rent an industrial-strength chipper that will chew up just about anything; perhaps your neighbors or association will share the cost. Now all you have to do is figure out what to do with all that mulch; just don’t spread it around your house. Often burning slash is prohibited during fire season, and regulated the rest of the year, along with other types of open burning. Check with your county so you understand local regulations and get the required permits.