During recent wildfires, 90% of homes and buildings were first ignited by embers, not the actual fire. Embers are carried on winds ahead of a fire, eventually causing a fire to “spot” ahead of itself. Spotting can occur several miles ahead of the main fire! Once these embers land on or near your home, it’ll depend on the building materials and the landscaping (or lack thereof) around the structure how well your house will fare.

embercast on traditional and fire-resistant test structures
For a wildfire simulation at the Insurance Institute for Business & Home Safety (IBHS), a house was built and landscaped on one side as a wildfire-resistant structure, and on the other side with common materials used when wildfire resistance is not a consideration. Photo Simon Kellogg (IBHS)

Ignition during a wildfire is the result of:

  1. Embers (also called firebrands)
  2. Radiant heat
  3. Direct flame contact

Retrofitting your home with a Class A fire-rated roof, replacing vent screens with 1/8th mesh screens or slatted screens, enclosing eaves, replacing single-pane windows with double pane and screened windows are well worth the investment.

Start at the top

Ember cast
Burning embers, known as firebrands, spread fire ahead of the flame front and can ignite buildings up to a mile away from the main fire. CAL FIRE photo

The roof of your home plays an important part in the defense against ember cast. Major wildfires can “spot ahead” miles from the fire front, igniting vegetation and homes well ahead of the main fire.

Cleaning your roof and keeping it free from debris and leaves is a recurring chore. Keep in mind, safety first. A sturdy ladder to access your roof and a person to hold the ladder are a must. The ladder can also be used by firefighters if they are attempting to defend your home from an approaching fire.

Wait until the roof is dry, slipping on a wet or icy roof – even a relatively flat one –  can lead to a fall and injury. Use a leafblower if available, or a broom. Using a garden hose to clean off a roof wastes water and increases the risk of a fall.

roof gutters

If your gutters don’t have debris guards (mesh or solid) installed, make sure to remove all leaves and debris accumulated. In case of embers falling on your house, any leaves in the gutters will ignite and set the roof on fire faster.

According to the Nevada County Building Department, new roofs building guidelines include:

  • Roofing material shall have a Class A fire rating.
  • Roofing valley metal flashing shall be minimum 26 gage with 36” wide 72lb cap sheet underlayment installed.
  • Roof gutters shall have debris guards installed.

Screens – small is better 

Roofing vents must be made out of ignition-resistant materials and have openings of 1/8”-1/16” only. Your favorite hardware store has these vents in stock, replacing them is an inexpensive way to reduce ember intrusion into the attic.


Exposed and closed eaves need to be built with non-combustible or ignition-resistant materials. If your home has open eaves, removing spiderwebs and other debris goes on your chore list when cleaning your roof.

Don’t forget the shed

Carports, barns, sheds and any other structure on your property (think well house) need to be kept free of leaves, just like your home.

Resources, permits and help

The Nevada County Building Department has resources available to help you upgrade any aspect of your home. Start by downloading their WUI brochure or the WUI Homeowner checklist for an overview of the latest building standards.

The State Fire Marshal has issued Wildfire (“CBC Chapter 7A”) Code Compliance Policies and Accepted Products. A searchable database of WUI building materials is available on the Office of the State Fire Marshal’s website.

Wood stoves, chimneys and proper ash disposal

Wood stoves are popular in the area, be that as a primary or backup heat source. Burning safely not only reduces health risks but also reduces the chance of chimney fires.

Be a good neighbor, build small hot fires rather than large smoldering ones. Using seasoned hardwoods produces much less smoke. Install smoke detectors/carbon monoxide sensors in your home or check the batteries of existing smoke detectors.

The Northern Sierra Air Quality Management District provides these three Burn Wise Tips:

1. Save money and time. Burn only dry, seasoned wood and maintain a hot fire.

  • Season and dry wood outdoors for at least 6 months before burning it. 12 months for hardwoods like oak.
  • Start fires with clean newspaper and dry kindling or consider having a professional install a natural gas or propane log lighter in your open fireplace.
  • Burn hot fires.
  • Don’t burn wet wood: it creates a lot of smoke and burns inefficiently.
  • Never burn garbage, plastic, or pressure treated wood, which can produce harmful chemicals when burned.
  • Learn more at EPA.gov about best burn practices.

2. Keep your appliance properly maintained.

  • To maintain proper airflow, regularly remove ashes from your wood-burning appliance into a metal container with a cover and store outdoors.
  • Have a certified technician inspect and service your appliance annually.
  • Have your chimney annually cleaned by a certified chimney sweep. Nearly 7 percent of home fires are caused by creosote build up in the chimney.
  • A properly installed and maintained wood-burning appliance burns more efficiently.
  • If you smell smoke in your home, something is wrong. Shut down the appliance and call a certified chimney sweep to inspect the unit.
  • Learn more at EPA.gov about correct installation and maintenance.

3. Keep your home healthy by upgrading to an efficient, EPA-approved wood-burning appliance.

  • Today’s wood-burning appliances burn cleaner and produce less smoke inside and outside your home.
  • Efficient wood-burning appliances burn less wood, saving time and money.
  • Learn how to choose the best appliance for your needs at EPA.gov. Click here to see if there are any active grants for replacing your old wood stove.
Reduce wood smoke in 4 steps

Can your ashes, have stoves and chimneys inspected and maintained

Proper disposal of ashes reduces fire danger for you and your neighborhood, especially during the Fall shoulder season. Firefighters regularly respond to vegetation fires caused by still hot ashes or BBQ coals improperly disposed of. Embers from hot ashes easily reignite!

woodstove chimney
  • Have heating equipment, chimney and stove inspected and cleaned by a certified chimney sweep every fall just before heating season.
  • Allow ashes to COOL before disposing of them. Four days or 96 hours is the minimum recommended cooling period for ashes.
  • Place completely cooled ashes in a covered metal container. Keep the container at least 10 feet away from the home and other buildings. They should NEVER be disposed of in a plastic garbage box or can, a cardboard box, or paper grocery bag. Never use a vacuum cleaner to pick up ashes.
  • The metal container should be placed away from anything flammable. It should not be placed next to a firewood pile, up against or in the garage, on or under a wood deck, or under a porch.
  • After sitting for a week in the metal container, check them again to be sure that they are cool. If so, the ashes are then safe to dispose of in your trash.
  • As a safety precaution keep anything that can burn at least three feet away from a fireplace, wood stove, or any other heating appliance, and create a three-foot “kid-free zone” around open fires. It is important to make sure the fireplace has a sturdy screen to stop sparks from flying, and never leave a fire unattended, particularly when children are present.

Next week we’ll repack Go Bags – for humans and pets – and talk about pet and animal evacuation preparedness.