Wildfire Mitigation Code Requirements

Origins of the Wildfire Code

Wildfires are unavoidable in Boulder County and the Western US. The Black Tiger Fire swept through the foothills of Boulder County, Colorado in 1989, destroying 44 homes and other structures and causing an estimated $10 million in damage. The fire highlighted the need for ignition resistant building codes in the county.

The conditions that principally determine whether a home survives a wildfire occur within 100 feet of the structure. This includes the home’s exterior materials, the surrounding landscaping and vegetation, and the agglomeration of urban and wildland fuels in this area. Boulder County’s Land Use and Building Code addresses these elements in order to reduce the risk of loss of life and property.

Initial measures to address wildfire resiliency through the building and land use code were adopted in 1993 and applied to construction in the western part of the county, designated Wildfire Zone 1. At the time, only this area was deemed at high risk from wildfires. The wildfire mitigation code requires the use of ignition resistant and noncombustible materials in home construction and limits the amount of flammable vegetation that can be allowed to grow near homes. These codes have been based on wildfire science findings from the US Forest Service Missoula Fire Science Laboratory, National Institute of Standards (NIST), Insurance Institute for Business & Home Safety (IBHS), National Fire Protection Association (NFPA), Cal-Fire and the University of California at Berkeley, and sections of the IWUI (International Wildland Urban Interface) Code. The county’s wildfire code requirements have been updated periodically as new science and standards become available.

The eastern part of the county had few notable fire events until the Marshall Fire in 2022. That fire destroyed almost 1,100 homes including over 150 homes in unincorporated Boulder County and over 900 in adjacent Superior and Louisville. This prompted the county to update its building code to include ignition resistant requirements for Wildfire Zone 2 as well, effective June 2022. The codes are a vital part of the county’s wildfire mitigation efforts, and they will continue to play an important role in reducing the risk of loss of life and property from wildfires.

Construction in West Boulder County Unincorporated Areas

The following applies to new construction in the unincorporated areas of western Boulder County, Wildfire Zone 1, loosely defined as the part of Boulder County west of Hwy 93, west of the City of Boulder, west of the Foothills Highway/Hwy 36. Boulder County requires wildfire mitigation for:

• New residences or commercial buildings.
• Additions over 200 square feet (In rare cases, defensible space may be required for additions under 200 square feet).
• Any deck project or deck work requiring a building permit.

Code Requirements

• Ignition Resistant Construction and Materials
• Fences, Retaining Walls, and Other Attachments
• Defensible Space Requirements
• Noncombustible Perimeter Requirements

A Firefighting Cistern Requirement applies to new residences only (not additions and remodels). The local Fire Protection District will provide specifics about what they will approve. Typically, it is one of the following:

• An individual cistern (of the correct size and type) sited and installed in an approved location. Fitted with the appropriate draft connection, filled with water, and tested by the fire protection district.
• A contribution for the installation, use, and/or maintenance of a community cistern made to the local fire protection district.
• A dry hydrant installed in an approved location in a local body of water, fitted with the appropriate draft fittings and tested by the fire protection district.
• A fire hydrant on a pressurized water system with sufficient fire flow must be located within an approved distance from the primary residence.

Unincorporated Boulder County Defensible Space Requirements

• Defensible Space FAQ’s
• New Homes
• Decks
• Additions: Require a Planning Process
• Additions: Do Not Require a Planning Process

Timeline

Defensible Space and the Building Permit Process

Typically, the Wildfire Mitigation Team does not have the capacity for any wildfire mitigation assessments or inspections before a building permit is applied for.

Prior to the Issuance of a Building Permit

A Wildfire Partners or Regulatory Wildfire assessment must be completed before a permit is issued. Once a building permit application has been submitted, a Wildfire Mitigation Specialist will contact the applicant. The Wildfire Mitigation Specialist works with the homeowner to select and mark trees to be removed to meet the defensible space portion of the building code. When the assessment is complete, your Wildfire Mitigation Specialist will notify the Permit Specialists and the permit will move forward.

Prior to Scheduling Any Above Ground Rough Inspections

This will take place once the walls and roof have been framed and sheathed. Contact a Boulder County Wildfire Mitigation Specialist at wildfireinspections@bouldercounty.org for an inspection. The majority of the defensible space must be completed by this point.

The Four Mile and Sunshine Fire Protection Districts require an Emergency Water Supply at this time for new homes.

A completed copy of the Fire Sprinkler and Fire Cistern Approval Form must be submitted to Boulder County Building Safety & Inspection Services at ezbp@bouldercounty.org.

At the Time of Final Inspections

Before a Certificate of Occupancy will be issued, all outstanding defensible space work will need to be completed and inspected. The noncombustible perimeter will need to be installed and inspected. Email wildfireinspections@bouldercounty.org to schedule this inspection.

In addition, for fire districts other than Four Mile and Sunshine, a copy of the Fire Sprinkler and Fire Cistern Approval Form with the Fire Cistern section completed must be submitted to ezbp@bouldercounty.org.

Construction in East Boulder County Unincorporated Areas

The following applies to buildings constructed in the unincorporated areas of eastern Boulder County, Wildfire Zone 2, loosely defined as the part of Boulder County east of Hwy 93, east of the City of Boulder, east of the Foothills Highway/Hwy 36.

Code Requirements

• The Ignition Resistant Construction and Materials requirements apply to all new exterior materials in unincorporated Boulder County. These are part of the building code and will be reviewed by the Building Safety team during the Plan Review. Link to R327.5 of the Boulder County Building Code Amendments.
• Additional requirements apply to fences, retaining walls, and other attachments. This is inspected by the Building Inspectors at the time of final inspections.
• The Noncombustible Perimeter Requirement defines acceptable hardscape surfaces that must be installed within 3 feet of the house and under decks.

Short-Term and Vacation Rental Licenses in Unincorporated Boulder County

Participation in Wildfire Partners is required for Short-Term Rentals and Vacation Rentals that are located in Wildfire Zone 1 (view Boulder County Wildfire Zones map).

• A Wildfire Partners assessment within five (5) years is required before the initial license will be issued.
• Wildfire Partners Certification is required at the first license renewal, after the first two years of operation.
• A Wildfire Partners re-assessment and re-certification is required every six (6) years.

Other Jurisdictions Wildfire Mitigation Related Codes

• City of Boulder Wildland Code
• Town of Erie Building Codes
• Town of Jamestown Building Codes
• City of Lafayette Building Codes
• City of Longmont Building Codes
• City of Louisville Building Codes
• Town of Lyons Building Codes
• Town of Nederland Building Codes
• Town of Superior Building Codes
• Town of Ward: Not available online