Wood Roof Fire Protection: Should You Spray Fire Retardant on Cedar Shakes or Shingles?
Fire Retardant Spraying on Wood Roofs: What Homeowners Need to Know
If you own a home with a cedar shake or wood shingle roof—especially in areas like Colorado’s Front Range or rural parts of Georgia—you’ve probably wondered: can I spray fire retardant to make my roof safer? The answer is: yes, but there are important factors to understand before you do.
Let’s break down when fire retardant spraying makes sense, what the building codes say, and what results you can realistically expect.
Can You Spray Fire Retardant on a Cedar Roof?
Yes, but not all fire retardant products are approved for field application on wood roofs. There are two main categories:
Factory-applied treatments (Class A, B, or C rated)
Field-applied sprays (used for maintenance or added protection)
According to the Cedar Shake & Shingle Bureau (CSSB), most Class A fire ratings can only be achieved with pressure-impregnated, factory-treated shakes or shingles—not spray-on applications.
That said, some Class B ratings may be achieved in the field using listed and tested fire retardant coatings, typically applied to the roof’s exterior after installation. These are often used as an added layer of defense, especially in wildfire-prone areas.
Does Fire Retardant Spraying Actually Work?
It can help—to a degree. Here’s what it typically does:
Slows flame spread
Reduces ember ignition potential
May buy extra time for firefighting
But here's what it won’t do:
Guarantee Class A fire performance
Permanently protect untreated wood
Prevent ignition from intense flame contact or radiant heat
Reapplication is usually needed every 3 to 5 years, especially in harsh weather climates like Colorado.
What Do Building Codes Say?
According to the International Building Code (IBC) and International Residential Code (IRC) 2021:
Class A/B/C fire ratings are only recognized when tested per UL 790 (ASTM E108)
Spray-applied coatings must be listed and labeled by a qualified agency
Many jurisdictions do not recognize field-applied coatings as meeting code without testing and approval
That means spraying your roof doesn’t automatically make it “code-compliant”—but it may still reduce fire risk.
When Is Fire Retardant Spraying a Good Idea?
It’s often used as a preventive measure in:
Wildland-Urban Interface (WUI) zones
Remote or forest-adjacent neighborhoods
Areas with high ember exposure
Homes where re-roofing isn’t immediately possible
If your roof is aging but still serviceable, a fire retardant spray can be a temporary risk-reduction solution.
Tips for Spraying Fire Retardant on Wood Roofs
Hire a licensed contractor with experience applying roof-safe fire retardants
Use only UL-listed or ICC-ES approved spray coatings
Reapply every few years—especially after hail or UV exposure
Combine with defensible space and gutter cleaning for best results
FAQs
Does spraying fire retardant void my cedar roof warranty?
Yes, in many cases. Always check with the shake/shingle manufacturer or CSSB before applying any coating.
Can I get a Class A fire rating by spraying my roof?
No. Only factory pressure-treated wood products meet Class A rating criteria.
Is fire retardant spraying required by law?
Not usually, but some WUI zones may require Class B or better performance—check local code.
Final Takeaway
Fire retardant spraying can’t replace a Class A roof system, but it may reduce fire risk if you have an existing wood shake or shingle roof—especially in wildfire zones.
If you’re in Colorado or Georgia and considering whether fire retardant spraying is right for your wood roof, reach out to Roof Nuts for expert advice and certified inspections.
📞 Colorado: 303-276-2403
🌐 RoofNutsCO.com
📞 Georgia: 404-476-6851
🌐 RoofNutsGA.com
We’re here to help protect your home and your peace of mind.
