Wildland Fire - Home Safety

Posted from 05/07/2007

Source: National Interagency Fire Center, Firewise, MSNBC research

Anatomy of a Wildland Fire

Wildfires live and die by the land, fuel and weather that surround them. The wrong combination could quickly turn a smoldering ember into a uncontrollable fast-moving inferno.

Fuel: Almost anything will burn under the right conditions -- trees, shrubs, grass, even peat or humus. Take away its fuel and the fire stops. This is central to firefighting strategy. Areas dense with dry trees, for example, are quickly identified by firefighters as potential problems.

Terrain: Fires tend to travel uphill faster than downhill. For flames to spread, they must preheat surrounding fuel. That heat transfer accelerates when the fodder is above the fire. A sloped countryside can also affect wind patterns, often pushing fires uphill in a hurry.

Temperature/humidity: The higher the temperature, the closer fuel is to its ignition point. And, as humidity declines, plants tend to give up more of their moisture to the atmosphere. These two effects typically drive fire intensity higher in the daytime and lower into the evening.

Wind speed and direction: Uncontrollable and often unpredictable, wind is a firefighter's worst enemy. Fast-moving winds can push flames toward fresh fuel and provide a constant supply of oxygen, which boosts intensity. Large fires can actually create their own intense wind systems.

How They're Fought

The battle to beat back flames varies depending on the fire's size and available resources. When a wildfire grows, threatening people and structures, fire crews employ some common tactics.

Threatened homes: The safety of residents and firefighters is top priority, according to the National Interagency Fire Center. Whenever possible, hand crews race in front of the fire to evacuate communities, then dig and remove fuel surrounding homes before the fire closes in.

Spray zone: Helicopters and planes continuously spray retardant and water in front of the fire. This won't stop large infernos, but it can slow them down long enough to evacuate homes and allow firefighters to gain ground surrounding the fire with trenches.

Backfires: The best way to fight fire is with fire. Hand crews set small controlled "backfires" around the fire line to exhaust flammable foliage. Sometimes these backfires backfire, burning out of control. Wind direction can also push flames away from such traps.

Trenches: Large wildfires usually grow in a widening elliptical shape from their flashpoints. Hand crews begin digging trenches along the fire lines from an anchor point behind the flames in hopes of eventually encircling them. These trenches create a break in the fires' fuel lines.

Anchor point: Soon after flames are spotted, an initial attack team descends upon the scene, often by helicopter. The staging area, or anchor point, is a safe distance behind the fire. From there, hand crews of about 20 men will start digging trenches alongside the flames.

Command post: As wildfires grow, so do the resources to fight them. Management teams set up remote command posts in clearings or nearby towns to coordinate and budget an extended attack. This is usually located well behind the fire.

Protect Your Home

The farther away you live from fire services, the more the burden of wildfire protection falls on your shoulders

Screens: One wayward spark is all it takes. Screen chimneys and cover vents with noncombustible wire mesh screening. Areas below the ground line, such as under the porch should also be screened.

Upkeep: Sweep gutters, eaves, and the roof on a regular basis. Stack your firewood well away from anything that is combustible, including fences and outbuildings.

Terrain: Protection begins with property evaluation. Some areas are less naturally fire safe than others. Narrow canyons, for example, draw fire like natural chimneys and accelerate the fire's rate. Choose a level area for construction. Fire spreads rapidly, even on minor slopes.

Road access: Homeowners should know the location of the closest fire department. What are the condition of the roads and bridges leading to the property? Cul-de-sacs need a radius large enough - at least 45 feet - to accommodate a fire truck. Property and roadways should be clearly marked.

Windows: Choose thick tempered safety glass and add nonflammable shutters. Home builders should minimize the size and number of windows on the side of the house that would likely be exposed to a fire. Windows should not face trees or shrubs that are closer than 30 feet away.

Landscaping: Create a safety zone of at least 30 feet by removing flammable vegetation, wood piles, and debris. Use fire resistant plants. Trim dead or low-hanging branches from trees and shrubs. Beyond 100 feet from the house, dead wood and older trees should be removed or thinned.

Eves: Roof eaves should be designed with minimal overhang to prevent heat or flames from becoming entrapped.

Roofing/walls: According to fire experts, untreated wood shake roofs are the primary cause of home loss to fire in wild land area. Homeowners should choose noncombustible or fire resistant materials for the both the roof and exterior walls.

Source: National Interagency Fire Center, Firewise, MSNBC research

NBC News’ Chip Reid and Javier Morgado, The Associated Press and Reuters contributed to this report

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