Gel and /or foam is usually applied directly to a structure. It’s efficacy usually lasts 2-48 hours depending on weather and fire conditions.
Long Term Fire Retardant is usually applied to vegetation to create a 20’ – 50’ perimeter around the structure and ingress / egress areas may also be treated. It’s efficacy usually lasts 4-6 months or upon receiving 1/2“ of rain or more.