The new wildfire building code, in plain English

Last reviewed: July 9, 2026

Colorado’s first statewide wildfire building code reached full effect on July 1, 2026. Most of what’s written about it is either code-speak or panic. Here’s what the code itself says, including the parts that surprise people.

Who it applies to — and who it doesn’t

The Colorado Wildfire Resiliency Code (CWRC) was adopted by the state’s Wildfire Resiliency Code Board on July 1, 2025, based on the 2024 International Wildland-Urban Interface Code. Local governments with designated wildland-urban interface (WUI) areas had until April 1, 2026 to adopt it and July 1, 2026 to be fully compliant — each jurisdiction adopts its own version, sometimes with local amendments and its own WUI map. Jefferson County, for example, runs its own WRC with a Class 1 / Class 2 overlay map for unincorporated areas.

The code applies to construction, alteration, movement, and repair of occupiable structures in designated WUI areas. Two things it does not do:

• It is not retroactive. A home standing legally before adoption continues as-is (§102.8) — the code doesn’t order existing, untouched homes to retrofit.
• The state’s WUI code map is not an insurance map — see the two-maps explainer.

The 25% triggers (the part that surprises people)

The code reaches existing homes through renovation events:

• Roofs (§101.6): replace 25% or more of your roof’s surface area — or do work that effectively replaces the covering — and the entire roof must be brought up to the code’s fire-rating requirements for new construction.
• Exterior walls (§101.7): replace 25% or more of your total exterior wall surface and the whole wall assembly must use compliant materials — and the zone within 5 feet of the structure must be brought into defensible-space compliance at the same time.

If you’re in a WUI-mapped area and pricing a partial reroof or new siding, ask your contractor and your building department about these thresholds before signing the bid. Crossing 25% can change the scope and cost of the whole project — better to know at the estimate stage.

Other provisions worth knowing

• Manufactured homes: HUD-code homes are exempt from structure-hardening on first installation, but a HUD-code home moved into a code area becomes subject to the code (§101.2.3).
• Defensible space: the code carries its own defensible-space requirements (Chapter 5), including the noncombustible zone in the first 5 feet — the same zone insurers’ models weigh.
• Historic buildings: jurisdictions may create historic-preservation exemptions (§102.9.1) — ask locally.

What to actually do

1. Find out if you’re in a mapped WUI area — your county or town building department has the adopted map (Jefferson’s is interactive; see your county’s page).
2. Planning exterior work? Get the 25% question answered in writing with the bid.
3. Building or buying new in the WUI? The code’s hardening and defensible-space requirements are now part of the permit path — Eagle County also requires a Wildfire Hazard Rating on permits, with inspections above a moderate rating.

Defensible-space work that satisfies the code is the same work that moves your insurance risk score and qualifies for the tax credit. One properly documented project, three payoffs — the form below connects you with a contractor who works to code.