Ignition resistant construction is required on homes that are threatened by wildfire. These areas of concentrated threat are typically known as the Wildland Urban Interface (WUI). Boulder's WUI is mostly on the western side of the city, though there are pockets within city limits and on the city's eastern flank that could be dangerous given the right conditions for fire ignition.

Ignition resistant construction comes in three tiers: Type 1, Type 2, and Type 3. Type 1 ignition resistance represents the most stringent building requirements and is typically designated in areas that have steep, inaccessible topography, relatively limited access to hydrants, and a combination of other factors. Type 3 is the least stringent and can be found in areas that face reduced, but still present, risk of wildfire.