Interior Fire Retardant for Lumber & Plywood

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3.00 LBS





FX Lumber Guard penetrant is a Class A fire retardant wood treatment (tested to ASTM E2768, certified, and listed by ICC, IAPMO, and Intertek Laboratory) for sawn lumber, plywood, and OSB. The species of materials treated and tested are Southern Yellow Pine (sawn lumber and plywood), Spruce Pine Fir, Hemlock Fir, and Doug Fir (sawn lumber and plywood); other species of similar materials are allowed to be included for Class A treated.
(ref: ASTM D5516 - The results of the three listed species (Southern pine, Douglas fir, and either white spruce or a Spruce/Fir mixture) are allowed to be used together to make inferences on untested wood species because the three tested species represent the full spectrum of expected treatability).

The 2024 IBC recognizes the ASTM E2768 as alternate testing for FRTW. The 2021 and 2024 IBC states under the definition of Fire-Retardant Treated Wood, the following:
Reference only: “FIRE-RETARDANT-TREATED WOOD. Wood products that, when impregnated with chemicals by a pressure process or other means during manufacture, exhibit reduced surface-burning characteristics and resist propagation of fire” (ASTM E84 Extended or ASTM E2768), both of which FX Lumber Guard fire-retardant penetrant has passed with a Class A results with reduced surface-burning characteristics and no flame progression beyond 10.5 feet of the center line of the burner at any time during the test.
FX Lumber Guard has multiple other tests, the same as FRTW, with passing results.

FX Lumber Guard is certified as a one-application fire retardant at 300 – 350 square feet per gallon (ref: ICC ESR 3872, IAPMO UER 478, and Intertek CCRR 1044). FX Lumber Guard is certified and listed by ICC (for the US, ICC - ESL1087, and Canada ICC - ESL1064), IAPMO, and Intertek Laboratory. FX Lumber Guard has been tested (ASTM E84 & ASTM E2768) on PSLs, Cedar, I-Joist, and Black Locust Lumber with the results of a Class A fire retardant.

FX Lumber Guard has been tested using the same standards as FRTW, with no degradation, no delamination of sheathing, and no phosphate-based chemicals.
The application of the fire retardant chemical is not what passes the test. The formulation of the chemical is what passes the test.
FX Lumber Guard meets the NFPA 703 Standard for Fire-Retardant-Treated Wood and Fire-Retardant Coatings for Building Materials, ASTM E2768, UBC42.1, UL723, NFPA 259, CAN/ULC S102, AWPA E12, ASTM D5664 Lumber, ASTM D5516 Sheathing, ASTM D3201 same testing procedure as FRTW.




FX Lumber Guard is an interior fire retardant penetrant that can be applied in field applications. There are numerous projects where raw materials can be treated, and they are not limited to wood framing, wall sheathing, wooden furniture, reclaimed wood, wooden doors, and much more.

FX Lumber Guard is not a coating; most coatings have been tested to the ASTM E84 Surface Burning Characteristics standard for flame spread and smoke development. Fire Retardant Coatings has a retreatment requirement of 2 - 5 years, and FX Lumber Guard is tested to the extended surface burning characteristics requirement and has no retreatment requirements. FX Lumber Guard meets the NFPA 703 / 255 (ref: ICC ESR 3872, IAPMO UER 478, and Intertek CCRR 1044), UBC 42.1, AWPA U1 UCFA Interior, UL 723, AC 363 Compliant, California Building Code, California Residential Code, and Califonia Fire Code Compliant.

Straight cuts and cross cuts on sawn lumber do not have to be retreated; if sawn lumber is ripped, the rips must be retreated afterward. Plywood and OSB can be cross-cut, straight-cut, and ripped with no requirement for retreating.

FX Lumber Guard & FX Lumber Guard XT 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.


FX Lumber Guard is a permanent application. Results: Class A (ASTM E84 Permanency test conducted in February 2016)

FX Lumber Guard has been tested on sawn lumber, plywood, and OSB to the maximum standards for fire retardants. Some examples of testing are not limited to the following.

ASTM E2768 - Surface Burning Characteristics (extended ASTM E84) Results: Class A fire retardant penetrant (average flame spread is five and average smoke index is 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 conducted in Sept. 2019.

ASTM E2768 - Surface Burning Characteristics (extended ASTM E84) Results: Class A fire retardant when applied to Southern Yellow Pine Sawn Lumber. The test was conducted in February 2015.

ASTM D3201 -Standard Test Method for Hydroscopic Properties of Fire-Retardant Wood and Wood-Based Products. Results: Moisture Content was 19.9% when the test ended and applied to Southern Yellow Pine sawn lumber. The test was conducted 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 conducted 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 conducted in May 2018.

ASTM D3043 -Standard Test Method for Structural Panels in Flexure. The test was conducted 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. The test was conducted in June 2018.

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

ASTM E119 - Standard Test Method for Building Construction and Materials Fire Test. ASTM E119 was modified to meet the requirement of the International Residential Code IRC 302.13 exception #4. Based on IRC 302.13, exception #4 requires the I-Joist to have a fire resistance equivalent to a 2x10 or greater dimensional lumber. Not the whole assembly, so to achieve this code requirement, ASTM E119 had to be modified from the standard. Results: ASTM E119 (Modified) 17 minutes with a load factor of 14%, and the criteria for I-Joist fire requirement allows for a smaller test size, stating “No less than 12 feet”. So, a 13-foot by 8-foot size assembly was tested (104 square-foot assembly) 

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 conducted 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) sawn lumber and 3/8 OSB in February 2016. 

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

The beneficial values of using FX Lumber Guard are that it is non-toxic, non-hazardous, environmentally safe, shallow to no VOC content or emissions, odorless, 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 or exceeds the industry requirements.

Some insurance companies have been known to give discounts for using FX Lumber Guard.


13 Reviews

  • 5
    Great Service, Great Product

    Posted by Dan on Feb 12th 2021

    Lumber Guard is easy to use and does what it says it does. Customer service was great to make sure I ordered the right product for my purpose and shipping was fast.

  • 5
    Great product!

    Posted by Jim Davis on Jan 11th 2021

    Easy to apply, no odor, and the wood accepts normal primer and paint afterwards. I'm using this for wood paneling on an attic cathedral ceiling. Getting full sheets of drywall up the narrow attic stairs would be impossible, so I am fireproofing the wood paneling before fastening on top of foam board insulation in order to meet code. This was the perfect solution.

  • 5
    FX Lumber Guard

    Posted by Fred Howard on Oct 29th 2020

    Purchase & Delivery fast and easy. Fast and easy to apply, works as advertised.

  • 5
    FX Lumber Guard

    Posted by Ralph G Paslay on Dec 14th 2019

    Product We just completed install on new construction I joist very easy to work with and clean up.No smell.