Class A fire retardant material
Building codes define a "Class A" fire retardant material as one that has a Flame Spread Index of 25 or less and a Smoke Developed Index of 450 or less in the ASTM E 84 Standard Test Method for Surface Burning Characteristics of Building Materials, or in one of two other similar tunnel tests. Tests of FLAMEDXX OSB yielded indices of 10 and 20, well within the Class A limits. Class A materials have more permissible applications in building codes.
No progressive combustion in extended ASTM E 84 test
The basic ASTM E 84 test lasts for 10 minutes. Building codes accept this basic test for some applications. For more critical applications, a material must show "no progressive combustion" when the basic test is extended to 30 minutes. This is the requirement for fire retardant treated wood produced by pressure treatment and for other substitutes for noncombustible materials. It is a difficult criterion for fire retardant coatings, and is met by very few. FLAMEDXX OSB has been subjected to the extended test period and showed no progressive combustion.
Suitable substitution for noncombustible panels in many code applications
Because it meets the Class A definition and showed no progressive combustion in the extended fire test, FLAMEDXX OSB can be used in a range of code-controlled applications, including roof and wall sheathing.
No significant reduction in strength
Invasive treatments can reduce the design values of wood products, causing strength reduction factors to be considered in designing a structure. The coating on FLAMEDXX OSB does not significantly reduce panel strength. This has been confirmed by various ASTM tests. The published strength values for uncoated OSB may be used.
No greater corrosion to metal than uncoated OSB
The fire retardant coating does not accelerate corrosion of metal fasteners or connectors, as shown in AWPA E 12, Standard Method of Determining Corrosion of Metal in Contact with Treated Wood. Metal corrosion may still occur because of atmospheric conditions - which is why galvanized steel is recommended - but the coating does not increase corrosivity.
Smoke emissions well below allowable toxicity limits
FLAMEDXX OSB has underdone the UPITT Test for Combustion Product Toxicity (morbidity rates) and the Boeing BSS 7239 test for gas emissions and results indicate levels well below toxicity limits.
Code evaluation report issued
An evaluation report (IAPMO ES report 0158) has been issued. This review gives local code officials the information necessary to accept FLAMEDXX OSB for multiple applications.
