Structural Composite Lumber (SCL) is an engineered wood product reconstituting wood strands or veneers with adhesives to form a more extensive and integral composite unit.
Regarding fire resistance, SCL is comparable with solid-sawn lumber products of equivalent dimensions. SCL is made of wood with a tiny percentage of thermal-set structural adhesives.
In applications requiring a fire-resistance rating, calculation procedures are used to obtain the fire-resistance rating of exposed structural wood products. The char rate for ASTM E 119 fire exposure is a critical factor in the calculation procedures. In this study, charring rates, observed failure times in tension tests, and deviations from predicted failure times of the structural composite lumber products were within the expected range of results for sawn lumber and glued laminated timbers.
However, it’s important to note that not all composite decking is created equal. Some composite decking materials are made of wood and plastic fibers, making them less susceptible to flame spread than many types of wood. Therefore, it’s always recommended to check fire ratings before you buy.
 by APA – The Engineered Wood Association.){kind=link}