Wildfire 101 – the basics

The link below is the first video of the series.   It is a YouTube video showing the Melody Lane fire in Reno, NV engulfing five houses in less than 10 minutes.  The setting is similar to what we have in our area.  This wildfire started in some sage bush and quickly moved up the slope to the houses along the ridge.  The fire department responded within five minutes, but that was too late to save most of the properties.  However with some prior wildfire risk mitigation work, these houses could have been made more defensible.


The Melody Lane Fire showed how a wildfire can spread from a grass/brush fire to five homes involved in less than 10 minutes.  It was dramatic footage, but there were things these homeowners could have done to mitigate their risk of a wildland fire.  In simple terms, if a house doesn’t ignite, it won’t burn.  The key is to do the little things that keep a house from igniting.  The Part 1 video at the link below provides insight into the science of fire behavior.  Please view the 10 minute video and think about what a person might be able to do that will reduce their and the community’s wildfire risk.


We learned that wildfire does not spread as a “wall of flames,” but with incremental ignitions of fuel.  In order for the fire combustion to exist there must be oxygen, heat, and fuel—remove one element and the fire does not continue.  The fire travels through thermal radiation (intense heat on fuel over time until combustion occurs), convection (direct flame contact on fuel), and/or conduction (transfer of heat energy from the fuel surface to interior from such things as firebrands—flying hot embers coming in direct contact with fuel).  The previous video introduced the home ignition zone concept—the layered defensible space around the house used to deny fire access to your home.  Keep the fire outside of the home ignition zone, and the house will most likely survive a wildfire.  If the home doesn’t ignite, it won’t burn!

In a dense conifer forest, the fire can be in the tree canopy (called a crown fire), burn hot, and travel fast.  Grass fires travel faster than crown fires due to the light, flashy fuel source.  Please watch the nine minute Part 2 video at the link below and pay special attention to how firebrands (burning embers) swirl like snow and can easily cause a house to burn.  As a piece of trivia, the farthest a firebrand is known to have traveled was 18 miles in Australia.


We learned we must evaluate all fuel sources in the Home Ignition Zone (layered defensible space around the house used to deny fire access to the home).  This may include the neighbor’s home/property.  A big threat is firebrands (hot flying embers) that spread like a snow blizzard, pile up, and cause fuel ignition.  The biggest vulnerability is the cedar shake shingled roofs where firebrands can settle on, between, and under dry, curled, cracked shingles.  Class A roofs and cement-based/steel siding don’t easily catch fire.  Keep the fire outside of the home ignition zone, and the house will most like survive the wildfire.  If the home doesn’t ignite, it won’t burn!

The 20-minute video at the link below explains fire behavior in the Wildland/Urban Interface (WUI—where we live).  The setting is a fictional community called West Creek Village which is very similar to our location with the National Forest and private properties up the hill and a town at the base of the slope.  We are more densely populated than shown in the video, but many of the fire behavior principles are in common with our community.  Once again, firebrands are the primary threat to West Creek and many of our towns.  Light fuels (needles, twigs, and small branches) generate the most firebrands with cedar fencing also being a big contributor.


If the home doesn’t ignite, it won’t burn!  You’ve heard this before, but what can you do to make your home ignition resistant?  Well you set a test house on fire to see what works.

The Insurance Institute for Business and Home Safety conducted experiments in their laboratory to determine what does and doesn’t easily burn.

Background:  The laboratory is located in South Carolina and was originally used for evaluating various construction techniques needed to withstand hurricanes.  The lab is a multi-story concrete building with a large turntable in the center on which the proposed building is constructed and slowly rotated.  The lab has a bank of high-speed fans used to generate hurricane-force winds and blast the structure.  The lab was later modified to assess what construction techniques are needed to withstand a wildfire.  The fans were throttled back to generate a 10 – 20 mph wind and five ember generators were installed to create flying firebrands bombarding the structure in a manner similar to a wildfire.

Test Setup:  A simple frame house was constructed on the turntable using a mix of building materials (composite shingle and cedar shake roof sections; fiber-cement, lap board, and vinyl siding; windows (open and closed); various roof venting schemes; various foundation plantings; wood and non-combustible mulches; and so forth).  The fans and ember generators were started as shown in the four-minute video at the link below.  Notice the turntable is slowly rotating.  Please see the test findings below after watching the video clip.

Ember Storm Demonstration

Findings:  Several conclusions were drawn from the testing.

  1. Composite (Class A) singles don’t burn.  Cedar shake shingles easily ignite and burn.
  2. Vinyl siding melts, droops, and falls thus exposing the sheathing to ignition.  Lap board siding ignites and burns.  Fiber-cement siding does not ignite.
  3. Debris (leaves and pine needles) in valleys and gutters quickly ignite.  The flames ignite the wood facia and soffit areas and thus burn into the attic.  Vinyl gutters melt and drop–metal gutters will not.  Metal fascia and soffits will resist ignition.
  4. Open windows allow flames and embers to enter the house.  Closed windows keep flames and embers out until the window fails.  Vinyl windows (unless reinforced with internal metal components) will eventually melt and drop the glass thus allowing flames and embers to enter the structure.
  5. Fiberglass window screens will melt when contacted by flame.  Metal screens will not.
  6. Open gable vents will permit embers to enter the attic and ignite the interior.  A 1/8” screen on the vents will help keep the larger embers out of the attic.  Attic vents parallel with the ground are more resistant to embers than those perpendicular to the ground and flying embers.  Closing all the attic vents prior to an approaching wildfire is the best way to keep embers out of the interior attic.
  7. Dry grass and oily-type foundation plantings (such as junipers) are quickly ignited and provide direct flame contact with the siding.  Deciduous plantings are less likely to ignite and burn.
  8. Woody-type and related combustible foundation mulch will easily ignite from embers and provide direct flame contact with the house.  Rock and other non-combustible mulch will not burn.

As you saw in the multiple videos, wildfire is a year-round threat in the Wildland-Urban Interface (WUI-where we live).  Flying embers (firebrands) are the probably the biggest threat in Cripple Creek.  The objective is to keep our homes from igniting during a wildfire through a series of defensive measures taken on our home and property.  Many of these measures are easy and cheap.  The Home Ignition Zone (HIZ) is the area around the house to focus your attention.  The HIZ can extend out to 200 feet which may not be practical in our community, so let’s start with the house and move out to the property line.  Below is a summary of lessons learned and other good practices.


Lessons Learned

Before the Fire (mostly easy and cheap):

  1. Keep your house address clearly marked and visible from both directions of traffic.  The firefighters can’t help you if they can’t find you.
  2. Keep leaf and pine needles off the roof, out of the rain gutters, away from the foundation, and from under trees/shrubs to a distance of 30 feet from any structure.
  3. Put a chimney cap or spark arrestor on all flues used for burning wood, solid, or liquid fuel.
  4. Keep grasses and weeds mowed to a maximum of four inches and watered (if possible).
  5. Remove dead, diseased, or weakened trees and shrubs.
  6. Remove ladder fuels by limbing up trees to eliminate flames on the ground from igniting shrubs, the lower tree limbs, and the structure or other materials.  Prune lower tree branches so fire can’t burn from the grass>shrubs>trees>structure.
  7. Remove liter and other combustibles from under the deck.
  8. Store firewood at least 15′ away from the house and decks.
  9. Use non-combustible mulch (such as rock), deciduous, or other non-ignitable landscaping to form a five foot non-flammable perimeter around the home.  Junipers are highly flammable and should not be in the landscaping plan.
  10. Seal any cracks or openings around the foundation, pillars, or other places where embers might collect or enter.  Use a 1/8” or smaller wire mesh to keep embers out and to allow water weeping.
  11. Ensure gable and other vents have at least 1/8” or smaller metal screen to keep the larger embers out of the attic space.  Attic vents parallel with the ground are more resistant to embers than those perpendicular to the ground and flying embers.
  12. Create a defensible space of at least 30’ around the structure(s).  Thin the landscaping, install fire breaks, and create barriers to stop the fire’s progression.  Barriers can be walkways, rock walls, rock mulch, and similar non-combustible materials for disrupting the fire’s path.
  13. Have the local Fire Department conduct a wildfire risk assessment of your property with mitigation recommendations.
  14. Maintenance—you’ve worked hard to protect your investment, so make sure you continue those efforts through regular maintenance.


When remodeling or building (more expensive options):

  1. Install composite (Class A) singles or metal roofing.  Check with the local building department for a list of approved products.
  2. Install fiber-cement siding, stucco, or other approved product that does not ignite or otherwise expose the sheathing to ignition.
  3. Install metal gutters, metal fascia, and metal soffits.
  4. Install windows and frames that are resistant to failure and reinforced with internal metal components.
  5. Build decks using fire-resistant materials.
  1. Use metal fabric in window screens.


Before the wildfire event:

  1. Have an evacuation plan with options.  There should be at least two ways into and out of your property.  Plan and rehearse an escape plan.
  2. Determine a safe-assembly point for all family members.
  3. Determine the pet and livestock safe-assembly point(s) and how they will be transported.
  4. Make a list of items to take in “Go Bag(s)” when notified to evacuate.
  5. Install a secure Knox box with keys and register it with the local law enforcement.   If needed, law enforcement and fire fighters can use the key to enter the home without breaking down the door.


When wildfire is approaching as time permits:

  1. Load the “Go Bag(s)” with pre-determined medicines, glasses, hearing aids, teeth, important papers, heirlooms, irreplaceable pictures, and other valuables.
  2. Fuel up the vehicles to be driven.  Charge digital devices and take their charging units.
  3. Load the vehicle(s) in advance of an evacuation order.  Take enough season-appropriate clothing to last at least a week for each person.
  4. Close the attic vents, if possible.
  5. Connect water hoses and sprinklers for the responders.
  6. Open gates (or take out a fence section) in wooden fences to create a fuel break leading to the house.  Wood fences can act as a fuse and lead fire toward the home.
  7. Remove flammable items from the patio or deck such as cushions, chairs, propane bottles, gas cans, welcome mats, brooms, padded furniture, and any flammable debris.
  8. Tightly close all windows and doors.
  9. Notify family and friends about your emergency situation.  Tell them about your evacuation plans.


If everyone in Cripple Creek applies the principles shown in the videos and summarized here, we are well on our way to becoming a fire adapted neighborhood.  If we keep our houses from igniting, they won’t burn.  Fire requires fuel.  We own the fuel.  No fuel, no fire.  Let’s keep our community safe from wildfires.


Special Thanks to resident and Fire Corps member Rich Ingold for gathering and organizing this content.