Tom Kalinski, RE/MAX of Boulder

With the recent Marshall Fire devastation, it’s painfully clear: we need to take steps to reduce our home’s risk to wildfire.

Research shows fire mitigation can reduce risk, but no one thing eliminates it completely. Colorado State University (CSU) identifies two factors critical in helping a home survive a wildfire – the defensible space around your home and the ignitability of the structure. Following is a short list of factors and recommendations from CSU, but be sure to check the CSU link below to see the full list.

Structural ignitability

Starting from the top, CSU notes the roof, eaves, decks, exterior walls, and windows need attention.

A fire-resistant roof tops the list for protecting your home. Wood and shake-shingle roofs are highly flammable and prohibited in some areas of the state. Asphalt shingles, metal sheets and shingles, tile, clay tile, concrete, and slate shingles are all recommended roofing materials, according to CSU.

Most decks are wood and highly combustible. To lower the risk, do not store materials under your deck and follow the guidelines for defensible space. Exterior walls are affected by radiant heat and direct contact with fire flames. Windows are one of the weakest parts of a building in a wildfire and usually fail before the building ignites.

Defensible space

Defensible space – or the area around your home – can help your home survive a wildfire, if fire fuels are cleared or reduced. CSU suggests that the design of your defensible space depends on your location, so you may want additional guidance from your local Colorado State Forest Service forester, fire department, or a consulting forester. Creating a proper defensible space does not mean that your home is guaranteed to survive a wildfire, but it does significantly improve the odds.

Defensible space falls into three zones:

Zone 1 is 0 to 15 or 30 feet from your home and other structures – including eaves and decks or porches. CSU recommends removing most flammable vegetation with the possible exception of a few low-growing shrubs or fire-resistant plants. Common ground junipers are highly flammable, so should be removed or not planted.

Recommendations for Zone 1 include:

  • Use nonflammable hardscape like gravel, pavers, concrete, and noncombustible mulch materials. Do not plant in this area and remove bark mulch, wood chips, pine straw, and other combustible ground covers.
  • Homes with noncombustible siding such as stucco, concrete, stone, or brick can have widely spaced foundation plantings of low-growing shrubs or other fire-resistant plant materials. However, CSU says “do not plant directly under windows or next to foundation vents, and be sure areas of continuous grass are not adjacent to plantings.”
  • Remove all dead branches, stems and leaves.
  • Water grass and vegetation during the growing season and keep wild grasses to a maximum height of six inches.
  • Keep firewood at least 30 feet away from structures and uphill, if possible.
  • For best protection, remove all trees from Zone 1. Trees in this area are considered part of the structure and incorporated in the defensible space measurement. Remove branches overhanging or touching the roof and all fuels within 10 feet of the chimney.

Zone 2 extends at least 100 feet from all structures. CSU recommendations for Zone 2 include the following. Check the CSU link below to see the full list.

  • Thin and prune trees by removing stressed, dead or dying trees and shrubs. Create at least 10 feet between crowns, which is measured from the outermost branch of one tree to the nearest branch of the next. On steep slopes, the distance should be greater.
  • Prune lower tree branches to a minimum of 10 feet from the ground.
  • Have only one or two dead trees per acre and clear from falling on the house, power lines, roads, or driveways.
  • Isolated shrubs are okay but not under trees and at least 10 feet from tree branches. Space shrub clumps at least 2.5 times mature height. If a shrub is 6 feet high, spacing between clumps should be 15 feet or more.
  • Do not stack wood against your home or on or under your deck and clear all flammable vegetation within 10 feet of wood piles.
  • Locate propane tanks and natural gas meters at least 30 feet from any structures. Do not locate them below or above your house, since the fire would burn uphill or leaks would flow into your home. Clear all flammable vegetation within 10 feet.

Zone 3 is the area farthest from your home and extends from the edge of Zone 2 to your property boundaries. Your local Colorado State Forest Service forester can help you with this zone.

This is a reduced list and there is a lot more to consider. It can seem overwhelming, but getting started is the first step. Be sure to read the full guide at:

Tom Kalinski is the broker/owner of RE/MAX of Boulder, the local residential real estate company he established in 1977. He was inducted into Boulder County’s Business Hall of Fame in 2016 and has a 40-year background in commercial and residential real estate. For questions, email Tom at [email protected],
call 303.441.5620, or visit