Exterior Fire Retardant for Lumber & Plywood

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50.00 LBS

FX Lumber Guard XT



FX Lumber Guard XT

FX Lumber Guard XT stands out as a Class A fire-retardant penetrant, meeting the rigorous ASTM E84 Extended/ASTM E2768 standards and the 2024 IBC 2303.2.1. We test on a variety of wood materials, from lumber to plywood to OSB, to prove its versatility.

In fact, FX Lumber Guard XT, along with our FX Lumber Guard Interior Fire Retardant Penetrant, is the only fire-retardant penetrant to pass the required testing with a 1/8-inch joint on plywood and OSB for the 2024IBC 2303.2 requirement. We used 1/2 syp plywood and 7/16 syp OSB, and both FX Lumber Guard XT and FX Lumber Guard have been tested for the application of roof decking (and passed). These unique features of FX Lumber Guard XT provides you with the assurance that you are using a product that is not only effective but also meets the highest industry standards. It's not just a claim-it's a fact that we've proven through our rigorous testing and compliance with various industry standards.

The testing of FX Lumber Guard XT was comprehensive, including materials such as Southern Yellow Pine, Spruce Pine Fir (SPF), Hemlock Fir, and Doug Fir (lumber) and Southern Yellow Pine, Doug Fir (1/2 plywood) along with Southern Yellow Pine (7/16 OSB) (includes other species of similar hardwoods and softwoods as treatable material).

NOTE*The results of the three listed species, Southern Yellow Pine, Douglas Fir, and either white spruce or a
Spruce/Fir mixture, are allowed to make inferences on untested wood species, as these three species represent the full spectrum of expected treatability
ref: ASTM D5516.


FX Lumber Guard XT is not just a highly effective fire retardant, but it's also a responsible choice for the environment and applicators. It's odorless, colorless, non-toxic, and non-hazardous, ensuring the safety of both the environment and the people using it. It's non-corrosive and Green Guard Gold Certified by UL Environmental Laboratory for low VOCs (emissions and content), making it suitable for interior applications.

We've conducted additional evaluations on various materials, from wood framing to wooden furniture, fencing, decks, reclaimed wood, and preservative-treated wood. When used on preservative-treated (green stuff) material, the material must be dry to the required moisture content of our evaluation reports and the building code before the application of FX Lumber Guard XT.

The application permanently impregnates the material, ensuring long-lasting safety. It's evaluated using the same standards as FRTW, with no degradation, no delamination of sheathing, and no phosphate-based chemicals, giving you peace of mind about its safety and environmental impact.

Standards of Testing – Tests are listed below

NFPA 703/255, ASTM E2768, ASTM E84 Extended / UL723, UBC42.1, ASTM E119, NFPA 259, ASTM D2369, CAN/ULC S102, AWPA E12, ASTM D5664 Lumber, ASTM D5516 Sheathing, and ASTM D3201.

CSI Division Codes: 06 05 73.33 Fire Retardant Wood Treatment.


FX Lumber Guard XT, when used for interior applications, the certified listings for interior use are valid (ICC, IAPMO, and Intertek certifications).

FX Lumber Guard XT is evaluated to the same standards as FRTW; examples of the following testing are detailed below.

FX Lumber Guard XT has been rigorously tested to meet the highest standards. It's a class A fire retardant penetrant, with an average flame
spread of five and an average smoke index of 45 when applied to SYP Plywood and SYP OSB. Both test samples had the required 1/8 joint
and roofing nails applied (required for roof decking). The test was completed in September 2019.

FX Lumber Guard XT & FX Lumber Guard were the first to achieve
the Class A fire retardant requirement of the IBC Codes of a 1/8 joint for sheathing (plywood and OSB), demonstrating its superior performance.

∙ ASTM E2768 - Surface Burning Characteristics (extended ASTM E84) standard for flame spread and smoke development, and the flame shall not
progress more than 10.5 feet beyond the centerline of the burners at any time during the test (exact requirements as FRTW).
Results: Class A. The test was completed in February 2015 (numerous tests).

∙ ASTM D3201 - Standard Test Method for Hydroscopic Properties of Fire-Retardant Wood and Wood-Based Products. Results: The moisture content of
Southern Yellow Pine with FX Lumber Guard XT applied was 19.9% when the test ended. The test was completed in November 2017.

∙ ASTM D5516 - Standard Test Method for Evaluating the Flexural Properties of Fire-Retardant Treated Softwood Plywood Exposed to Elevated
Temperatures. The test was completed in December 2017 and February 2024.

∙ ASTM D5664 - Standard Test Method for Evaluating the Effects of Fire-Retardant Treatments and Elevated Temperatures on Strength Properties of
Fire-Retardant Treated Lumber. The test was completed in May 2018.

∙ ASTM D3043 - Standard Test Method for Structural Panels in Flexure. The test was completed in December 2017 and February 2024.

∙ AWPA E12 - Standard Method of Determining Corrosion of Metal in Contact with Treated Wood. Results: Non-corrosive when applied to raw southern
yellow pine lumber. The test was completed in June 2018.

∙ ASTM D2369 - Standard Test Method for Volatile Content of Coatings. Results: VOC .06% / g/l .65. The test was completed in August 2015.

∙ NFPA 259 – Standard Test Method for Potential Heat of Building Materials. Results: Potential Heat of Combustion of ½ SYP Plywood is 7,729 Btu/Lb,
and 7/16 OSB Sheathing is 8,247 Btu/Lb. The test was completed in October 2021.

∙ ULC S102 - Standard Method of Test for Surface Burning Characteristics of Building Materials and Assemblies. Results: Class A fire retardant when
applied to SPF (Spruce, Pine, Fir) lumber and 3/8 OSB in February 2016.

∙ UL 2818 - Standard for Chemical Emissions for Building Materials, Finishes and Furnishings. Results: FX Lumber Guard XT is Green Guard Gold

The value of using FX Lumber Guard XT: shallow to no VOC content or emissions, permanent application, stainable (water-based products only),
paintable (water-based products only), will not change the looks of the material treated, and has testing values that meet the fire-retardant industries
requirements for FRTW. FX Lumber Guard XT is not a sealer, pest control, or UV blocker; use a water-based wood sealer to protect the material from
rotting; you may also use rot-resistant wood for your project.


22 Reviews

  • 5
    FX lumber Guard XT

    Posted by Ted Smith on May 6th 2022

    I have used this product for 5 years to stop cigarettes from starting mulch fires on my commercial sites

  • 5
    Just what we needed

    Posted by Dan on Feb 23rd 2022

    The product is fantastic. Easy to install. I hope to never have to test it out. All the documents and tests will be good to have if the city needs to see what we treated the lumber with. Also, the team was outstanding. They answered every question we had.

  • 3
    FX Lumber Guard XT

    Posted by Edward Perry on Oct 1st 2021

    Might be a good product. Unfortunately, product sheet only discusses its universal application. The technical sheet explains that you can only use WATER BASED products on it. I need a product that will accept an oil base stain.

  • 4

    Posted by Marty Gallagher on Sep 14th 2021

    I applied it. Application was very easy. I am using it on siding. I have top coated it with a clear sealer. There have been no fires in my neighborhood threatening my home, so I don't know how if it protects my home yet.

  • 5
    FX Fire Retardant

    Posted by Wendi D. on Sep 1st 2021

    Very pleased with this company, their customer service was awesome!. Excellent product that shipped fast!!

  • 4
    FX lumber guard xt

    Posted by Mary k Trimble on May 31st 2021

    Delivery extremely prompt and people lovely to work with. Product easy to apply with a hand sprayer, I sprayed the entire exterior of my wooden house as I live way off the beaten path at the end of a box canyon...a fire trap if there ever was one. Hope I never have to test its efficacy:)

  • 4
    FX Lumber Guard Xt

    Posted by Steve Wolfrom on Dec 7th 2020

    One gallon was enough for my entire front porch surface, the posts and some of the bottom. I did, however, coat two sticks and let them dry fully, then threw them into a burn pit - they held out for a couple minutes and did not actually catch fire but they did char and burn.

  • 5
    Service and shipping

    Posted by Carl Freeman on Oct 27th 2020

    Sterling service, fast shipping!
    Look at their videos showing blowtorch tests! They also included safety data sheets and certificates to show your insurers. Best recommendation!

  • 5
    Service and shipping

    Posted by Carl Freeman on Oct 27th 2020

    Sterling service, fast shipping!
    Look at their videos showing blowtorch tests! They also included safety data sheets and certificates to show your insurers. Best recommendation!