What are the risks of decks, outside furniture, under deck storage and stairways?
Decking is best considered as an extensive fuel load attached to a house, where the heat from a decking fire itself is enough to ignite or break windows.
The deck itself is an issue, as well as the typical things we store on and under our deck: furnishings, plastic furnishings, barbecues, you name it. All can present a combined fuel load that can be formidable for a structure.
As well as stairs and stairways, any re-entrant corner or detail is an obvious place for debris to land and start to develop.
The importance of having non-combustible substructures under the decks, and under houses themselves, is absolutely critical.
There are very good behaving decks and deck solutions, and an obvious way to go is to use a steel substructure so the support systems aren't a fuel source themselves, and then either use high durability Class A durability timber top, but even better specific bushfire resisting wood composite decking systems that are specifically designed and tested to survive bushfires