5 Things to Consider When Buying a Home on the Wildland-Urban Interface

The Wildland-Urban Interface is where the unmanaged natural vegetation of the wildland that acts as the fuel for forest fires meets homes, ranches, businesses or any other human structures. The WUI brings along a unique set of challenges for homeowners because of the unpredictable nature of wildfires and the difficulty fire engines have accessing remote properties. Firewise Communities greatly reduce the risk of fire by creating a fuel-free “barrier” around the property to keep fire at a distance (known as a defensible zone) and by taking measures to ensure the home is impenetrable to the threat of airborne embers.

What’s the roof made out of?

Wood shake roof is a giant red flag – not only are wooden roofs the main reason a home catches fire when flying embers rain down, replacing an old roof could cost tens of thousands of dollars! Unless the house is specially priced to factor in that extra re-roofing expense, it may be best to avoid the problem by not buying that house to begin with.  Metal, concrete, asphalt and tile are all great roofing choices, and, with routine clearing of leaves from the rooftop and gutters, can ensure that your home is safe from flying embers.

Does the property have enough space for a defensible zone?

The best way to stay safe from fire is by creating a fuel-free zone around your home that stops the progress of wildfires – this is known as a “Defensible Zone”.  Defensible zones are fairly easy to create and closely resemble the average backyard - islands of raised plant beds surrounded by trim green turf. If a defensible zone is not yet in place, it’s not a deal breaker. They are cheap and easy to create – the important thing is that there is enough space to hold at least a 100ft defensible zone. Neighboring homes closer than 100 feet from your house that aren’t Firewise are also a real danger because you can’t control your neighbor’s willingness to prepare for fire, and if they go up in flames there is a good chance the fire will spread to your home.

Can this home be accessed by firefighters in an emergency situation?

Most wildfires threaten many homes at the same time, so firefighters don’t waste their time trying to save a home unless it can be located quickly from a main road, safely accessed by big fire trucks, and has enough water available for the fire engines to suppress the flames. When you drive up to that house for the first time, think to yourself, “Is the house address easily visible? Are these roads wide enough for a fire truck, and could it turn around? Will I have enough water during an emergency?”

Is there anything that could act as a bridge to carry flames right up to the house?

If you have a wooden fence, porch, or deck the answer is yes. Dead vegetation dries and piles up underneath decks and up against fences, and as you already know, it only takes one spark to burn down a house. Although it is perfectly fine to have fences and outbuildings on your property, you must always be aware of anything that can burn and transport fire up to the house. While you shop around for houses keep in mind that any flammable structure must be regularly maintained, whether that means clearing accumulated vegetation or installing a metal screen underneath decks to stop embers.

What is the risk level of the environment?

Are you considering a home that lies in the middle of a dense coniferous forest? Next to a lake? Surrounded by grassy fields? It wouldn’t be appropriate to prepare for wildfires the same way for each of these environments. You have to take into consideration how the local weather, plants, and land dictate how wildfires behave. For example: fires burn quickly uphill, so homes on a slope must compensate with a bigger defensible zone. It could be a good idea to contact your local fire department or federal land agency (Forest Service, BLM, etc.) to get information on local fire behavior patterns and how they may affect your home, because you will want to know ahead of time if there are any wind or drought patterns that could bring powerful or unexpected fires.

Smoke from Idaho: the Most Destructive Fire in American History

The August of the driest year in Idaho history hosted a cold front that produced hurricane-force winds and a wide-spread lightning storm. The combination of worst-case-scenario fuel dryness, wind speed, and lightning ignitions nursed a behemoth fire that ravaged the forests of northern Idaho and Washington with complete disregard to the firefighting effort. The “Big Burn” of 1910 consumed over 3 million acres, earning the distinction of being the largest fire in American history, a title it holds to this day – over 100 years later.

The numbers are startling, truly difficult to grasp. In 2 days an estimated 1000-3000 individual fires burned 3 million acres of forest, killed 86 people (including 2 men who committed suicide when the hellish fire couldn’t be outrun), and created a cloud of smoke reaching as far north as Saskatoon, Saskatchewan, as far south as Denver, and clear east into New York state. If all the lumber burned was put on 1 train it would stretch 2,400 miles long – roughly the distance between Boise and New York City. The massive loss of forest is still felt today, and many areas have still not recovered due to massive amounts of soil erosion from rain wash-outs.

The Big Burn of 1910 serves as a lesson and a grave warning. The possibility of another catastrophic fire is always present if the right set of conditions comes together. The combination of drought conditions that dry vegetation, widespread electric storms that cover a large area with scattered ignitions, and winds that blow with enough power to push flames over fire lines or mountain ranges will surely bring a huge fire. Our fire suppression tactics and technology have advanced greatly since 1910, but we can’t control fires, only manipulate them in ways that hopefully reduce damage to property and natural resources. The struggle to control fire is made harder by the effects of global climate change which has increased the global temperature, lengthened the dry season in many places, and has also altered wind circulation patterns.  Experts believe that these phenomena will most likely result in more severe and numerous wildfires. Although we haven’t yet seen another fire like the Big Burn of 1910 and our technology is much more advanced, there is still always a chance - especially with the added effects of Global warming - that all of the necessary conditions come together and ignite a monstrous fire like the Big Burn. Man’s most valiant efforts to control nature can be completely overwhelmed by an especially dry, windy fire.

Fire Behavior Triangle Explained

Unlike the Fire Triangle (heat, oxygen, fuel), The Fire Behavior Triangle explains how a fire acts after it is already ignited. The Fire Behavior Triangle is similar in that it is comprised of 3 parts - Weather, Topography, and Fuels – but the complexity of how these components interact on a large scale makes this mnemonic device much more important in the education of wildland firefighters and homeowners alike.

Weather.  The aspects of weather that have the greatest influence on fire behavior are wind, humidity, temperature, and precipitation. Wind has played a vital role in every catastrophic fire in history. It empowers fire by injecting oxygen for combustion and pushing the flames onto unburned fuel. Humidity and precipitation both influence the degree to which fuels are saturated with water, which is important because dry fuels burn easily, while wet fuels are difficult, often impossible, to ignite. Temperature plays a lesser role, but along with low humidity, temperature dries out fuel for a more intense burn.

Topography. Simply put, topography can be described as “the lay of the land”. It may seem odd, but fires don’t burn the same on all landscapes - fires burn much faster uphill because the rising heat from the fire dries out the fuels above it, priming them for easy and rapid combustion. This effect of fire behavior, along with the inaccessibility of mountainous areas to firefighters, makes it significantly harder to fight flames in steep terrains. Fire behavior is also greatly affected by the aspect, or direction the slope faces. Here on the Northern Hemisphere it is the southern-facing slopes that get the most direct sunlight, and therefore are the driest side of any mountain or foothill. Rivers, deserts, and lakes that impede the path of a fire are also included in this category, and are used by firefighters to help contain wildfires.

 Fuels. Anything that can burn in a fire is considered a fuel – grass, trees, piles of leaves, even your home! Areas with a high volume of fuel per acre have the greatest potential to burn intensely in the case of a fire. Dry fuels will burn easier. Fuels that are close together allow fire to spread quickly. In Fire Ecology there are 3 main types of fuels: Ground fuels, surface fuels, and canopy fuels. Ground fuels are combustibles that lie just under the surface, like buried logs or roots, and burn slowly because of the higher moisture and lower oxygen levels. Surface fuels lie on top of or just right above the surface and can include anything from pine needles, leaves, grass, shrubs, or even your back porch. Crown fuels, which typically refer to the crowns, or tops, of trees, are far and away the most dangerous fuel type. If a fire can make its way up to the crown it is significantly harder to suppress, and crown fires can actually spread separately from the ground fire it originated from.

      The Fire Behavior Triangle is a convenient mnemonic device used by fire professionals to quickly and easily teach the fundamentals of fire behavior to just about anyone. Although it’s great for the layman, the Fire Behavior Triangle isn’t exclusively for beginners - it is still taught to wildland firefighters today who need to be constantly aware of the risky, unpredictable nature of fire behavior. Fire behavior is complicated and hard to predict even for experts, but when broken down into its 3 most basic components it is possible to understand, on a very basic level, how fires act in different ecosystems, seasons, weather, or terrains.