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
    FXLumber Guard XT

    Posted by Cheryl Branch on Jul 9th 2024

    Easy to use, even post construction.

  • 5
    Some peace of mind

    Posted by Sharon on Oct 24th 2023

    Our order arrived quickly and well packaged. The fire retardant has a watery consistency which makes painting it onto wood overhead a bit of a messy job. We learned that latex gloves are a must. On the fence we were able to use a simple garden pump sprayer and it worked beautifully. Dries very quickly. The product is easy to clean up with soap and water. Now we feel some peace of mind knowing that our most vulnerable outdoor wood features are protected. And BTW, the fire retardant is invisible and our cedar continues to weather as before. Very pleased.

    One other learning: A review I read suggested that the retardant can be applied over a previously painted surface. We learned the hard way that that is NOT true. It seems the retardant must form a bond with the bare wood to be effective. When applied over painted wood, it formed an ugly white film that was challenging to get off. And if I understood the tech data correctly, it seems that the retardant has not been tested for effectiveness on treated wood is subssequently covered with paint, sealant, etc. So I think the moral of the story might be, apply any stain/paint, etc over the fire retardant treated wood at your own risk.

  • 5
    I force no issues what so ever. It's straight forward and meets NYS CODES Regulations. Applying it will be a piece of cake I can't Thank You enough for making it so easily available.

    Posted by Dan Phelps on Sep 28th 2023

    I plan to apply it this afternoon. At this point I can only say it was easy to order and select what I needed from the person who answered my phone inquiry on your product.

  • 5

    Posted by don walker on Aug 15th 2023

    As I live in a WUI , I need to have the exterior fire-resistant. 3 sides of the house are HardiBoard and front side is clear white cedar. which is pritected from the weather Used FX Lumber Guard XT to have it fire resistant. Used it also on a wood deck that also protected from weather, Applied a clear coat UV protection to preserve natural wood look.

  • 5
    Awesome Customer Service

    Posted by Chris Gregory on May 26th 2023

    We needed clarification on which product to purchase. They answered the phone on first call and went through why we needed this product, how to apply it and what to do for best results. Great customer service, they went above and beyond.

  • 5
    FX Lumber Guard XT

    Posted by James R. Boy on Jan 11th 2023

    Applies easily. Seems like the manufacturer has tested the product with the appropriate labs. I hope that we never have to test on the applied materials. We like this product !

  • 5
    FX Lumber Guard XT

    Posted by Deborah Verfaillie on Jul 29th 2022

    Goes on easily. Must choose cool of day - not 85 or over. We have been in the mid 90's so painted early this AM.

  • 5
    FX Lumber Guard XT

    Posted by Ed O'Neill on Jul 15th 2022

    Product was easy to apply and did not change the look of the wood, very natural

  • 5
    fire retrdant

    Posted by marty Flora on Jun 7th 2022

    we just received and are in the process of applying product to both our deck, doors, and fence.
    this is not the first time we've done this but first time with this product and we like it better than anything else we've used so far.
    easy to apply, and clear so the wood shows thru,