From NFPA Keep Your Deck Functional Not Flammable

Saw this article at NFPA 

Excerpt-

Q. What are the standards
for building a Firewise Deck?
A. Steve Quarles: Decks can be made from noncombustible
or combustible materials. An example of a noncombustible
deck is one that uses steel members or structural support and
a light-weight concrete and flag stone walking surface. An example
of a combustible deck is one that uses wood timbers and
joists for structural support and wood or wood-plastic composite
boards for the walking surface. As I’ll explain, not all combustible
materials are created equal when it comes to performance
when exposed to fire. Decks built using combustible
components are more common than decks that use noncombustible
components. Although building codes and standards
exist with provisions to reduce vulnerability of decks to wildfire,
these provisions have not been adopted statewide outside of
California.