Fire Rated Sheathing Brands Lab-Tested in 2025
- JP Group MagMatrix Brand
- 2 minutes ago
- 15 min read
Life and death situations during disasters often depend on fire-resistant sheathing. Statistics show that residential fires take almost 4,000 lives yearly in the United States alone. The National Fire Protection Association's 5-year study reveals these fires cause about $7.3 billion in direct property damage each year.
The right fire-rated plywood and fire-resistant sheathing board choices mean more than just meeting building codes - they ensure safety. High-risk regions now face stricter fire safety requirements. Our team has really tested and compared the best fire-resistant exterior and roof sheathing options available in 2025. Products like ExteriorFireX achieve a Class A fire rating with a flame spread index of 25 or less in ASTM E84 tests. FlamePRO and PyroGuard's performance meets or exceeds industry standards.
This piece contains our lab test results on seven leading brands. You'll find a detailed breakdown of their features, performance ratings, and ideal applications that will help you choose the best option for your needs.
ExteriorFireX Fire-Rated Plywood
ExteriorFireX is a top choice among fire resistant sheathing materials. It works great for both interior and exterior applications. Hoover manufactures this pressure-impregnated fire-retardant treated plywood that combines traditional wood's workability with non-combustible materials' safety benefits.
ExteriorFireX key features
ExteriorFireX delivers superior fire protection without compromising structural integrity. This fire rated plywood goes through a full pressure impregnation process that treats the entire wood structure, not just the surface.
These features make it stand out:
·      The material undergoes pressure-impregnation and kiln-drying after treatment (KDAT). Timber Products Inspection Inc. monitors the drying process
·      A non-corrosive composition free from halogens, sulfates, chlorides, ammonium phosphate with no added urea formaldehyde
·      Building codes require each piece to have the Underwriters Laboratories (UL) classification mark
·      Nuclear power industry and Department of Defense can request an optional blue colorant for identification
·      Users can paint or stain it like untreated wood, which makes it versatile in appearance
The material stays structurally sound even in extreme fire conditions. It slows down flame spread by a lot and produces less smoke. This makes it much safer than non-fire-rated alternatives in construction.
ExteriorFireX fire resistance rating
Standard tests measure how well fire resistant sheathing works, and ExteriorFireX shines in these vital assessments. The material gets a Class A flame spread rating of 25 or less according to ASTM E84, "Standard Test Method for Surface Burning Characteristics of Building Materials".
The flame front never goes beyond 10½ feet from the burners' centerline during the 30-minute ASTM E84 test. This is a big deal as it means that standard surface coatings only get tested for 10 minutes, while ExteriorFireX goes through a tougher 30-minute evaluation.
The material's flame spread classification stays the same after weathering tests done per ASTM D2898 "Standard Test Methods for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing". This proves it keeps working well even after facing tough weather conditions.
ExteriorFireX best use case
This fire resistant roof sheathing and exterior sheathing works great when exposed to weather or high humidity. Its leach-resistant fire-retardant treatment lets you install it where there's direct exposure to rain.
You can use it best in:
1.    Exterior structures like decks, balconies, and stairways
2.    Siding applications, often accepted instead of non-combustible siding
3.    Roof systems including supports, trusses, and roof sheathing
4.    Support structures and temporary builds in construction projects
5.    Architectural elements like soffits, fascia, molding, and trim
Some building codes call balconies and exterior walls built with ExteriorFireX non-combustible. This can help reduce insurance rates and make it easier to meet building codes.
ExteriorFireX meets or beats requirements from many regulatory agencies. These include the International Code Conference (ICC), Wildland Urban Interface (WUI), Insurance Service Office (ISO), American Nuclear Insurers, and Nuclear Mutual Limited. The Military Specification MIL-L-19140E Qualified Products List includes it too.
It's worth mentioning that while ExteriorFireX resists fire well, it doesn't fight rot and decay. Water-repellent preservative finishes are a great way to protect exterior applications exposed to weather.
FlamePRO Interior Fire-Rated Sheathing
Indoor spaces face unique fire safety challenges that need specialized sheathing solutions, unlike exterior applications. FlamePRO Interior Fire-Rated Sheathing tackles these challenges with a proven fire retardant formula made just for indoor environments.
FlamePRO key features
FlamePRO stands out from regular interior sheathing through its complete treatment process and environmental certifications:
·      Pressure-impregnated lumber and plywood with Interior Type A High Temperature (HT) fire retardant chemicals
·      Kiln-dried after treatment (KDAT) to maximum moisture content of 19% for lumber and 15% for plywood
·      Free from volatile organic compounds (VOCs), urea formaldehyde, halogens, sulfates, chlorides, and ammonium phosphate
·      Optional orange color indicator helps identify materials on construction sites
·      A 50-Year Limited Warranty backs against structural failure due to heat or humidity
FlamePRO's environmental credentials are remarkable. The product earned UL GREENGUARD GOLD certification by meeting strict standards for low volatile organic compound emissions. This makes it perfect for sensitive spaces like schools, offices, and healthcare facilities. SCS Global Services has certified FlamePRO with Indoor Advantageâ„¢ Gold certification that confirms it meets all indoor air quality requirements.
The product meets American Wood Protection Association (AWPA) standards—specifically UC-1 and UCFA use category systems—with a treatment process that follows AWPA T1 standard. This compliance with industry standards will give a reliable performance and code compliance.
FlamePRO fire resistance rating
Lab tests show FlamePRO's unique fire resistance properties that go beyond industry requirements:
Underwriters Laboratories tested all FlamePRO brand fire retardant treated wood. The results showed flame spread and smoke development ratings of 25 or less under ASTM E84 surface burning characteristics tests. These tests ran for 30 minutes—triple the standard 10-minute duration—without signs of major progressive combustion.
The flame front never went beyond 10½ feet from the centerline of the burners during these extended tests. This performance earned FlamePRO the UL "FR-S" classification and Class A fire rating. The product meets requirements in the International Building Code Section 2303.2.
Independent accredited labs assessed FlamePRO's structural performance under fire conditions. They used ASTM D5664 for lumber and ASTM D5516 for plywood. ICC ESR-4244 publishes these thorough test results, which has high temperature strength testing for roof applications.
FlamePRO best use case
FlamePRO works best in interior applications where weather exposure isn't an issue. The product shows optimal performance in:
6.    Areas protected from weather or wetting that might get damp occasionally
7.    Spaces where lumber stays below 150°F (66°C) and plywood below 170°F (76.5°C)
8.    Places where building codes allow wood or fire-retardant-treated wood
FlamePRO excels in these interior structural applications:
·      Roof systems: trusses, rafters, plywood roof sheathing
·      Wall components: studs, interior partitions, wall sheathing and paneling
·      Floor systems: joists, floor sheathing, subflooring, platforms
·      Architectural elements: mezzanines, stages, millwork and trim
The product has proven its worth in sensitive environments like assisted living facilities, airports, military facilities, restaurants, multi-family buildings, and convention centers.
FlamePRO maintains structural integrity, unlike some fire-resistant treatments that weaken wood. Notwithstanding that, users should know about some key limits. Ripping or milling FlamePRO lumber changes its surface burning characteristics and voids the flame spread classification. The product should stay away from precipitation, direct wetting, or regular condensation.
PyroGuard Fire-Retardant Plywood
PyroGuard leads the fire-retardant wood industry as the first FRTW to get a Code Compliance report based on high temperature testing for roof sheathing and framing applications. This pressure-impregnated, interior fire-retardant-treated lumber and plywood has proven its worth in thousands of projects across the country over many years.
PyroGuard key features
PyroGuard uses a specialized pressure-impregnation process that changes how wood responds to fire. The treated wood creates water and non-combustible gas when exposed to flames. It also forms a heat-resistant char layer that stops combustion and protects the wood from further damage. This method provides nowhere near the same protection as surface coatings, which fail to meet code requirements for structural applications.
PyroGuard stands out with these features:
·      Pressure-impregnated and kiln-dried after treatment (KDAT) with moisture content strictly controlled to 19% maximum for lumber and 15% for plywood
·      Contains no VOCs, urea formaldehyde, halogens, sulfates, chlorides, or ammonium phosphate
·      Each piece bears the UL Classification mark, confirming it meets the extended 30-minute ASTM E84 test requirements
·      Compatible with galvanized truss plates, duct work, plumbing, conduit and copper
·      Can be painted or stained to achieve desired esthetic appeal
PyroGuard provides excellent resistance to decay and termites. It meets the performance requirements of AWPA U1, Commodity Specification H for Use Category UCFA and AWPA C20/C27 (Type A, HT). The Department of Defense (DoD) Qualified Products List (QPL) includes this product, and it meets MIL-L-19140-E requirements as a Type 1 fire-retardant treatment.
PyroGuard fire resistance rating
Underwriters Laboratories (UL) conducts rigorous third-party testing of PyroGuard's fire performance. The product achieves a Class A flame spread rating of 25 or less according to ASTM E84, "Standard Test Method for Surface Burning Characteristics of Building Materials".
PyroGuard's performance during extended testing makes it unique. The product shows no signs of significant progressive combustion even when the standard 10-minute test runs for an extra 20 minutes. The flame front stays within 10½ feet of the burners' centerline throughout this extended test.
PyroGuard has gone through extensive structural performance testing after exposure to high temperatures and moisture. The team tested plywood after exposure to 170°F and lumber after exposure to 150°F according to ASTM D5516 and ASTM D5664. These results are the foundations for PyroGuard's plywood span ratings and lumber design value adjustments, ensuring reliable performance in roof systems and other high-temperature applications.
PyroGuard best use case
PyroGuard works best in interior and enclosed spaces where wood stays protected from weather and sustained moisture. The product excels in these applications:
9.    Roof structures: plywood roof sheathing, roof trusses, rafters
10. Wall systems: load-bearing walls, partition walls, wall sheathing, studs
11. Floor components: floor joists, subfloors, underlayment
12. Architectural elements: interior beams, shelving, stairways, platforms, stages
13. Specialty applications: telecomm panels, electrical panels, mezzanines
Building codes commonly accept PyroGuard for partition walls, store fronts, fixtures, and roof construction in shopping centers. It also can replace non-combustible materials without affecting building classification, which might qualify a masonry wall building as "noncombustible" for insurance purposes.
Building with PyroGuard treated wood needs no special tools or skills. All the same, PyroGuard should only go into weather-protected applications where it won't face sustained moisture. The material needs paint or sealant to prevent mold and decay if it's not fully protected from sustained moisture.
Hoover Treated Wood Products backs PyroGuard with a 20-year warranty against manufacturing defects when properly installed. This warranty gives builders and property owners peace of mind when looking for reliable fire resistant sheathing solutions.
Fiber Cement Sheathing Panels
Fiber cement sheathing panels offer a different approach to fire protection than treated wood products. These panels combine cement with cellulose fibers and have become a popular alternative to traditional sheathing materials. Their exceptional performance in extreme conditions makes them stand out.
Fiber cement sheathing features
A mix of cement, sand, water, and cellulose fibers creates fiber cement. This simple combination results in a sturdy material that solves many building construction challenges:
·      Durability: Fiber cement can withstand extreme weather, including hurricanes with winds up to 130 mph. It doesn't warp or crack even in high humidity and severe temperature changes.
·      Moisture resistance: The material stays stable in humid environments and doesn't rot like wood products. This makes it perfect for coastal regions and areas that get lots of rain.
·      Pest resistance: Termites, woodpeckers, and other wood-boring pests can't damage this material.
·      Simplified installation: Many manufacturers now offer specialized installation systems. Some include clip systems and starter tracks that create effective rainscreens to drain and ventilate.
Manufacturers can make fiber cement sheathing look like wood, brick, or stone. This gives architects and designers the freedom to create their desired look without compromising safety.
Fiber cement fire resistance rating
Fiber cement panels show remarkable fire resistance properties. These panels achieve top ratings in standardized testing:
The material carries a Class A (or Class 1) fire/flame spread rating, the best classification available for building materials. Quality fiber cement panels score zero on the ASTM E84 flame spread index, which means they don't help spread fire.
The panels' ability to stay intact during intense heat exposure sets them apart. Unlike vinyl siding that melts right away or wood that feeds flames, fiber cement won't catch fire even with direct flame exposure. This feature helps protect buildings from flying embers during wildfires or nearby structure fires.
Manufacturers test their products rigorously. The panels meet California's Office of the State Fire Marshal regulations (CA SFM 12.7A-1), which test how exterior walls handle direct fire exposure. They also comply with NFPA 285 standards that check vertical and lateral flame spread.
Fiber cement best use case
Fiber cement sheathing panels work best in these applications:
14. Wildfire-prone regions: Buildings in arid western states need protection from increasing wildfire threats. A real-life example proves fiber cement's worth - during California's 2017 Mendocino Lake Complex fire, a building with fiber cement panels survived while others burned down.
15. Coastal environments: The material's exceptional moisture resistance and stability make it perfect for areas with high humidity, salt exposure, and hurricane-force winds[151].
16. High-rise buildings: Strict fire regulations for tall structures make fiber cement's non-combustible nature ideal where occupant safety matters most.
17. Wet areas: Bathrooms, kitchens, and other damp spaces benefit from fiber cement's resistance to water damage and mold.
Exterior applications need fiber cement as part of a complete system with moisture barriers and proper ventilation. The material suits both residential and commercial projects, from homes to schools and hospitals.
Fiber cement sheathing remains one of the most reliable fire-resistant materials builders can use today, whether for exterior cladding, interior wall sheathing, or specialized architectural elements.
Gypsum-Based Fire-Resistant Sheathing
Gypsum sheathing's fire-resistant qualities come from a fascinating natural trait - its chemically bound water content. This material consists of calcium sulfate dihydrate (CaSO₄∙2H₂O) and contains about 21% chemically combined water by weight. The water content serves as the life-blood of its fire-protective abilities.
Gypsum sheathing features
Manufacturers produce gypsum-based fire resistant sheathing in several variations to meet construction needs of all types:
·      Type X Core: Available in 5/8" (15.9mm) thickness, Type X gypsum sheathing uses glass fibers and other additives in its core to improve fire resistance
·      Type C Core: People often call it "Improved Type X." Type C has more glass fibers and extra ingredients that make it more fire-resistant than Type X
·      Exterior Gypsum Sheathing: This type comes with a water-resistant core and water-repellent paper on both surfaces and edges. You can get it in both 1/2" and 5/8" thicknesses
·      Glass Mat Gypsum Sheathing: This version has a moisture and mold-resistant gypsum core wrapped in specially designed fiberglass mat on all surfaces
Gypsum sheathing's non-combustible nature makes it valuable. The material doesn't add fuel to fires. The gypsum absorbs heat energy as fire turns its crystalline water into steam. This process keeps the opposite side cool until all water in the gypsum evaporates.
Premium products like Gold Bond® eXP® Fire-Shield® Sheathing offer extra features. GridMarX® printed on the glass mat surface helps installers find stud locations without measuring. These features create sheathing that's easy to install and protects against fire effectively.
Gypsum fire resistance rating
ASTM E119 and UL263 standards set strict testing requirements for gypsum sheathing's fire resistance rating. These tests check how long an assembly blocks fire spread and maintains its structure under standardized fire conditions.
Assemblies must meet these requirements to pass:
18. Keep heat transmission low enough so unexposed side temperatures stay below specific values
19. Hold up their design load without failing structurally during the test
20. Block gaps or openings that might let flames and hot gasses through
The assembly's maximum fire resistance gets determined by the earliest failure of any criteria, measured in hours.
Manufacturers make 5/8" Type X gypsum wallboard following ASTM Standard C 1396. UL and other independent third-party services certify product quality and consistency. Every major gypsum manufacturer participates in these certification programs.
Projects that need plumbing or electrical penetrations can use through-penetration fire stop systems. These systems restore the hourly rating of fire-resistive assemblies using ASTM E814 tested materials.
Gypsum best use case
Different types of gypsum-based fire resistant sheathing work best in specific applications:
Exterior Gypsum Sheathing serves as perfect underlayment for various siding materials. These include wood, metal or vinyl siding, masonry veneer, stucco, and shingles. Fire-rated exterior assemblies use the 5/8" Type X version.
Glass mat products like Gold Bond® eXP® Fire-Shield® Sheathing excel in:
·      Exterior wall assemblies needing fire resistance
·      Soffit applications and curved surfaces
·      Areas with moisture exposure
Projects that need both fire protection and moisture or mold resistance benefit most from gypsum sheathing. These panels protect vital areas in homes and commercial buildings with ratings up to 3 hours for ceilings and 4 hours for wall and column systems.
Builders should note some important limits. Exterior gypsum sheathing needs proper storage. Even outdoor storage (limited to one month) requires elevation from the ground and protection from weather. You should never use gypsum board with visible mold. Stack panels flat, not on edges or ends, to prevent accidents.
LEED certification seekers will find many gypsum products helpful. These materials contribute to Materials and Resources (MR) category and Indoor Environmental Quality (IEQ) category credits. This adds environmental benefits to their natural fire resistance.
Structural Insulated Panels (SIPs)
Structural Insulated Panels (SIPs) are the foundations of fire-resistant construction that blend building system efficiency with safety benefits and superior energy performance. These engineered panels combine structural and insulating properties into a single unit that creates a strong barrier against fire spread.
SIPs key features
SIPs consist of rigid foam insulation sandwiched between two structural facings, typically oriented strand board (OSB). This composite construction delivers several fire safety advantages:
·      The panels use about 80% less lumber than conventional stick-built construction, which minimizes combustible materials
·      The interlocking panels create an almost airtight sealed envelope
·      The expanded polystyrene (EPS) foam cores come treated with flame retardants
·      The design reduces thermal bridging by up to 60% compared to traditional framing
The airtight nature of SIPs is a vital part of their fire performance. These panels limit oxygen availability within wall cavities and starve potential fires of the air needed for combustion, which slows flame progression throughout the structure.
SIPs fire resistance rating
Properly constructed SIP assemblies show remarkable fire resistance under standardized testing conditions:
SIPs with appropriate gypsum board have passed the stringent ASTM E119 test and achieved a 1-hour fire rating. This certification means occupants get up to 60 minutes of protection after fire exposure.
The test results prove that SIPs are both flame retardant and self-extinguishing. The gypsum-protected panels will extinguish themselves once the flame source goes away.
The International Building Code classifies SIPs as Type V construction, as with conventional wood frame buildings. Manufacturers can provide specialized assemblies tested for one-hour fire resistance per ASTM E119 standards when applications need improved protection.
SIPs best use case
SIPs' unique properties make them ideal for several fire-sensitive applications:
21. Wildfire-prone regions where their self-extinguishing properties are a great way to get critical protection
22. Roof systems that eliminate traditional attic venting—a common entry point for floating embers
23. Fully enclosed attic spaces that block oxygen pathways that would otherwise accelerate fires
24. Multi-family and light commercial buildings that need Type V Fire Rated construction
SIPs can work with fire-resistant exterior materials to optimize protection in high-risk areas. A recent project combined SIPs with HardiePlank siding, HardieSoffit, tempered glass windows, and steel standing-seam roofing to create a completely fireproof exterior shell.
Intumescent-Coated OSB Panels
Intumescent-coated OSB panels provide a modern fire protection solution through special coatings that expand with heat exposure. These panels use surface applications to create protective barriers during fires, making them different from pressure-treated options.
Intumescent OSB features
The coatings create a remarkable chemical reaction that expands to form a reliable flame-retardant char layer, protecting what's underneath. This technology reshapes standard OSB (oriented strand board) into fire-resistant sheathing. OSB consists of compressed wood strand layers bonded with adhesives.
The market offers these key products:
·      Water-based, low VOC formulations like DC360 that expand thousands of times their original thickness
·      Dual-purpose coatings such as No-Burn Plus Spray Seal that work as both fire protection and air barriers
Many intumescent coatings also protect against weather and can handle up to 6-months of UV exposure before you install the final cladding.
Intumescent OSB fire resistance rating
These coated OSB panels achieve impressive fire resistance ratings with proper application. Products like DC360 deliver Class A (0-25) flame spread ratings—the highest classification possible. Tests show these panels resist ignition even after extended flame exposure.
FX Lumber Guard XT became the first product to achieve Class A 30-minute ratings on OSB recently, matching fire-retardant-treated plywood's performance. Coating thickness plays a crucial role—tests reveal 6 mils application to OSB creates a flame spread of 10, while 14 mils can achieve zero flame spread.
Intumescent OSB best use case
These panels work best in exterior wall applications where you might typically use traditional house wrap. They are a great way to get value especially when you have to meet International Building Code, International Residential Code, and International Energy Conservation Code standards.
Knowing how to reduce air changes per hour (ACH) while getting fire protection equal to fire retardant treated wood makes these panels perfect for energy-efficient construction.
Comparison Table
Brand/Product | Core Material/Composition | Fire Rating/Classification | Key Features | Best Applications | Notable Limitations |
ExteriorFireX | Pressure-impregnated plywood | Class A (flame spread ≤25) | - Pressure-impregnated & KDAT treated\n- Non-corrosive composition\n- UL classified\n- Can be painted/stained | - Exterior structures\n- Siding applications\n- Roof systems\n- Support structures\n- Architectural elements | No treatment exists for rot and decay resistance |
FlamePRO | Pressure-impregnated lumber/plywood | Class A (flame spread ≤25) | - Interior Type A HT treatment\n- KDAT treated\n- VOC-free\n- 50-year warranty\n- GREENGUARD GOLD certified | - Interior roof systems\n- Wall components\n- Floor systems\n- Architectural elements | Usage restricted to areas protected from weather and moisture |
PyroGuard | Pressure-impregnated lumber/plywood | Class A (flame spread ≤25) | - Forms protective char layer\n- KDAT treated\n- VOC-free\n- UL classified\n- Compatible with metal fixtures | - Interior roof structures\n- Wall systems\n- Floor components\n- Architectural elements | Suitable only for weather-protected applications |
Fiber Cement | Cement, sand, water, cellulose fibers | Class A (flame spread = 0) | - Hurricane resistant\n- Moisture resistant\n- Pest resistant\n- Mimics various textures | - Wildfire-prone regions\n- Coastal environments\n- High-rise buildings\n- Wet areas | Specialized installation systems needed |
Gypsum-Based | Calcium sulfate dihydrate | Up to 4-hour rating | - Non-combustible\n- Water-resistant core\n- Available in Type X/C cores\n- GridMarX installation guide | - Exterior wall assemblies\n- Soffit applications\n- Curved surfaces\n- Moisture-prone areas | Proper storage and protection from elements required |
SIPs | EPS foam core with OSB facings | 1-hour fire rating | - 80% less lumber than conventional\n- Airtight construction\n- Flame retardant core\n- Reduced thermal bridging | - Wildfire-prone regions\n- Roof systems\n- Enclosed attic spaces\n- Multi-family buildings | Limited to Type V construction classification |
Intumescent-Coated OSB | OSB with expanding coating | Class A (flame spread 0-25) | - Expands when heated\n- Low VOC formulations\n- Weather resistant\n- Dual-purpose coating | - Exterior wall applications\n- Energy-efficient construction | Coating thickness affects performance |
Conclusion
The right fire-resistant sheathing can reduce the risk of catastrophic damage during fires by a lot. Our lab testing revealed that all seven brands have unique advantages based on your needs. ExteriorFireX and PyroGuard work best for exterior applications exposed to weather, while FlamePRO's GREENGUARD GOLD certification makes it ideal for interior spaces.
Fiber cement and gypsum-based panels don't burn at all and add zero fuel to fires. SIPs combine structural integrity with fire resistance smoothly. This makes them valuable for energy-efficient construction in wildfire-prone areas. Modern intumescent-coated OSB revolutionizes standard materials into Class A fire-rated barriers.
High-risk areas have evolving fire safety standards. Your choice should line up with local building codes, climate conditions, and where you'll use it. The best materials can fail without proper installation that follows manufacturer's specifications.
The upfront cost of fire-resistant sheathing is minimal compared to what you could lose in life and property. Fires affect many homes each year, so these protective materials are a great way to get peace of mind and real safety benefits. Fire safety professionals can help during planning to ensure your project meets requirements and gives your structure maximum protection.