External or balcony decking can be installed on bearers or joists. Normally boards are either 90mm or 65mm and are available in many species. The most common is Tallowwood, but also available are Spotted Gum, Blackbutt, Red Ironbark, Grey Ironbark, and imported species such as Merbau and Balau.
At other times more species are available like West Australian Karri and Jarrah, but they are becoming scarce. An alternative to the traditional small space between boards is to use Tongue and Groove boards with the top of the groove removed and then filled with a caulking product such as Sikaflex. This produces a finish similar to ship’s decking with a black or coloured line filling the joint.