Structure Ignition Zone: Self-Assessment

Wildfires are common in Wisconsin. A look at fire occurrence over the past 10 years shows that nearly two-thirds of the wildfires in our state began on private property. Often, when a fire starts on private property, homes and other buildings are threatened and sometimes destroyed or damaged by the wildfire. Research has shown that the characteristics of buildings and their immediate surroundings determine the risk of ignition during a wildfire.

The Structure Ignition Zone

The structure ignition zone is your home and its surroundings out to 100-200 feet. You can make your home more likely to survive a wildfire by reducing the amount of fuel in this area.

If your home does not meet the standards for each of the recommendations below, there is still work you can do to better prepare your home for wildfire. By reducing or changing the fuels around your home, you are removing the fuel a wildfire needs to burn.

Fire-Resistant Construction

Is the roof is made of fire-resistant materials?

The roof is the most vulnerable part of your home and at the most risk of being exposed to flying embers. For this reason, it is very important that roofing materials be fire-resistant. Use Class-A asphalt shingles, metal or other fire-resistant roofing material.

Are the exterior walls fire-resistant?

Ideally, exterior walls on buildings in fire-prone areas should be made of materials such as brick, stucco, fiber cement or logs. These products are much better able to resist heat than vinyl, which can soften and melt. If updating your siding is not an option, you should take extra care to keep vegetation, dry needles and leaves, firewood and other flammable materials away from your home.

Are the eaves and vents covered?

Eaves and vents are possible points of entry into your home for flying embers that may be blowing around during a wildfire. Vents should be screened with a non-combustible wire mesh with openings not more than 1/8 inch in size. Eaves should be boxed in with 5/8 inch plywood or a fire-resistant material.

Are attachments made of fire-resistant or non-combustible materials?

Decks, porches and balconies are hazardous by design because they are generally made of flammable materials and are usually flat, which provides the ideal location for flying embers to land, smolder and ignite other materials they come in contact with. Use heavy timber or noncombustible construction materials.

Lean, Clean And Green Landscaping

Is vegetation away from windows?

Windows can break when exposed to heat, which can allow embers to enter your home. Keep the area around windows clear of flammable vegetation such as evergreen shrubs and trees as well as tall plants.

Are there very few (if any) plants within 0-5 feet of the home?

While plants are not recommended in this area, if you do choose to have some here, low-growing plants and deciduous shrubs are preferable to evergreens. Plants should be well-spaced, well-maintained and interspersed with non-combustible materials.

Is there mulch or non-combustible mulch within 0-5 feet of the home?

Wood mulch can ignite during a wildfire and should not be next to flammable siding. Ideally, the area 0-5 feet around a home should be bare dirt, mowed grass or non-combustible materials such as brick or decorative stone.

Are evergreens limited within 30 feet of the home?

Evergreens are highly flammable and are not recommended within 30 feet of buildings. If you choose to have some in this area, keep them separated from one another and prune their lower branches up and away from the ground.

Is vegetation thinned in the zone 30-100 feet from the home?

The area that extends out 30-100 feet around the home can be very important in slowing an advancing wildfire if the vegetation is managed correctly. Create space between branches of evergreen trees. Encourage a mixture of deciduous and evergreen trees and shrubs. Create "fuel breaks" by incorporating mowed grass, garden islands and non-flammable features.

Regular Maintenance

Is fallen debris cleared off the roof, out of gutters and window wells, underneath decks and away from foundations?

Roofs, rain gutters, decks and balconies are common places where fallen leaves, needles and other flammable debris accumulate. They are also likely places for flying embers to land during a wildfire. Routinely remove debris from these places. Consider installing “gutter guards” over rain gutters and fire-resistant screening under decks to simplify future maintenance.

Are tree limbs trimmed back at least 10 feet from roof?

Overhanging branches can drop leaves/needles directly onto a roof or in rain gutters, creating a maintenance problem. Branches overhanging a roof can cause a building to ignite should that tree catch fire.

Are branches on evergreens pruned up and away from the ground?

Keeping lower branches of evergreens away from the ground may prevent a surface fire from igniting lower limbs. Once an evergreen begins to burn, the whole tree can quickly become engulfed by flames. Routinely rake away any debris that collects underneath branches.

Is the lawn kept mowed, green and free of leaf litter and needles?

Lawns that are allowed to dry out during times of drought as well as lawns that are covered with fallen leaves, needles and branches provide a wildfire with the "fuel" it needs to continue burning. Keep lawns raked free of fallen debris, especially in spring and when weather conditions make wildfires more probable. Grass around buildings should be mowed short and watered in times of drought.

Is the yard free of dead trees and shrubs?

Dead vegetation, which can get very dry, is more likely to ignite by flames or flying embers than live vegetation. Keep trees and shrubs free of dead wood and remove any dead and dying trees and shrubs around buildings.

Safe Distance To Flammables

Are outbuildings located within 30 feet of the home clear of flammables?

If buildings are within 30 feet of one another, the ignition of one could result in the ignition of the other. Because of this, it is important to make sure each building has lean, clean and green landscaping and regular maintenance.

Are firewood and other flammable materials at least 30 feet from buildings?

Firewood stacks, wood scraps, brush piles and stored vehicles are at risk of ignition from flying embers and surface fire. If these combustibles are near buildings, it increases the likelihood of the building igniting as well. Store firewood and other flammables at least 30 feet from buildings. Go one step further and create a cleared area around them.

Are powerlines free of overhanging branches and nearby dead and dying trees?

Trees that are close to powerlines are potential ignition sources, should the tree or branches fall on the lines. Contact your public utility to remove branches and dead and dying trees around power lines.

Are propane tanks or fuel oil tanks free of combustible materials in the surrounding area?

Clear the area 10 feet around propane tanks. Keep surrounding grass short and green. To reduce maintenance, fill in the area with non-combustible materials such as decorative stone or gravel.

Do nearby neighbors have 30 feet of defensible space around their homes?

Nearby neighbors have 30 feet of defensible space around their homes: If there are other homes within 100 feet of your home, the quality of their defensible space can have an effect on your property if a wildfire burns through the area. Talk to your neighbors about wildfire safety and work together to lower your overall risk.