Building Permit

Colorado Wildfire Resiliency Code

Commercial and Residential Projects

Refer to the Colorado Wildfire Resiliency Code (CWRC) map to determine the fire intensity classification. Click on the map link on the state website and find the property in question. If the property is split between hazard ratings, please contact your local fire district to perform “ground truthing” to determine the appropriate fire intensity classification. See the Colorado Wildfire Resiliency Code web pages for exceptions.

Colorado Wildfire Resiliency Code map

See your rating zone for fire intensity classification on the Colorado state map.

Hazard intensity classification

In the medium/high hazard intensity classification, please provide a hard copy and digital copy of a “wildfire mitigation plan.” This can be included in the site plan or can be a separate drawing. This plan needs to show how the existing vegetation and new vegetation will comply in all three ignition zones. Please refer to the CWRC and handouts for details. Also show distances to neighboring buildings.

In the medium/high hazard, please specify on the drawings:

• Type of siding, including the manufacturer. It is to be noncombustible or fire resistive. The fire resistive type will require a specification document that meets the definition in the CWRC.
• Type of exterior decking material, including the manufacturer. Provide the specification document to verify class A flame spread or for composite decking class B flame spread is met.

There are basically 3 classifications: no hazard, low hazard and medium/high hazard.

No hazard

No wildfire requirements. It is recommended but not required.

Low hazard

This is an outline, refer to the CWRC for details

Class 1 structure hardening – for low fire intensity areas (Yellow). Please refer to chapter 4 – section 403. Class 1 requires the following:

• Roofing must be class A rated.
• Gutters and downspouts must be noncombustible.
• Ventilation openings (e.g., in attics, crawl spaces) must be covered with listed vents or noncombustible corrosion-resistant mesh with openings not to exceed â…›-inch to resist ember and flame intrusion.

Structure ignition zone 1 (0-5 feet), “defensible space”

The immediate zone (applies to classes 1 & 2)

• Is designed to reduce or eliminate ember ignition and direct flame contact with the structure.
• Use noncombustible, hard surface materials like rock, gravel, or concrete.
• Removal of all plantings including shrubs, slash, combustible mulch, and other woody debris, with an exception for ignition-resistant vegetation from an approved list either created by the Colorado State Forest Service (CSFS) or a list created by the AHJ that meets or exceeds CSFS fact sheet 6.305. Ignition-resistant landscape plants – fact sheet 6.305.
• There shall be no planting of new trees. Existing mature trees must have crowns pruned to maintain a 10-foot clearance from any structure. Branches must be pruned to 6–10 feet from the ground or one-third of the tree’s height, whichever is less.
• Site signage: requirements for marking access roads/driveways, fire protection equipment, and posting visible address markers visible from both directions.
• Retaining walls: must be noncombustible or ignition-resistant if within 8 feet of a regulated structure or integral to its support/egress. Also required if a retaining wall is integral to the egress from a structure regulated by this code to a public way, easement, or private road.
• Fencing: fences within 8 feet of a regulated structure (or to the property line if closer) must be noncombustible or ignition-resistant, though vinyl fencing may be an exception.

Medium/high hazard

This is an outline, refer to the CWRC for details

Class 2 structure hardening – for moderate or high fire intensity areas (orange or red). Please refer to chapter 4 – section 404. Class 2 requires all class 1 requirements, plus the following:

• Eaves and soffits must be protected on the underside by noncombustible, ignition-resistant, or 1-hour fire-resistance-rated materials.
• Exterior wall coverings must meet specific fire-resistance ratings or be constructed of approved noncombustible, heavy timber, pressure-treated, fire-retardant treated wood, or ignition-resistant materials.
• Exterior wall coverings are limited to noncombustible, pressure-treated fire-retardant treated wood, or ignition-resistant materials (vinyl siding is allowed only if the underlying wall assembly meets specific fire-resistance ratings).
• A minimum of 6 inches of flashing is required vertically between the wall sheathing and the exterior cladding at the ground, the decking, and at roof intersections.
• Unenclosed decks require a class A walking surface (exception: composite walking surface with a class B rating).
• Exterior glazing (windows, glazed doors, skylights) must be tempered glass, multilayered panels (dual pane), glass block, or have a fire protection rating of at least 20 minutes. (No single pane)
• Exterior doors must be noncombustible, solid core wood at least 1Âľ inches thick, or have a fire protection rating of at least 20 minutes.
• Gaps around vehicle access doors (like garage doors) must not exceed â…› inch to resist ember intrusion.

Structure ignition zone 1 (0-5 feet), also know a defensible space: refer to low hazard in previous section for this zone

Structure ignition zone 2 (5-30 feet): The intermediate zone (applies to class 2)

• This zone is designed to give an approaching fire less fuel and to reduce its intensity.
• Hazardous dead plant material must be removed, and large accumulations of surface fuels should be avoided.
• Tree crowns must be spaced to promote fuel discontinuity to limit fire spread and maintain 10-foot clearance from structures. Shrub groups must be spaced to prevent structure ignition and be at least 10 feet from the edge of tree branches.

Structure ignition zone 3 (30-100 feet): The expanded zone (applies to class 2)

• This zone focuses on mitigation that keeps fire on the ground.
• Tree crowns within this zone shall be spaced at a minimum of 6–10 feet.

Additional site requirements (applies to classes 1 & 2):

• Site signage: Requirements for marking access roads/driveways, fire protection equipment, and posting visible address markers.
• Retaining walls: Must be noncombustible or ignition-resistant if within 8 feet of a regulated structure or integral to its support/egress. Also required if a retaining wall is integral to the egress from a structure regulated by this code to a public way, easement, or private road.
• Fencing: Fences within 8 feet of a regulated structure or neighbor’s structure (or to the property line if closer) must be noncombustible or ignition-resistant, though vinyl fencing may be an exception.