It is Aluminium, with a coating to make it look like timber. It's called DecoWood - http://www.deco.net.au/

The only timber in this picture is in the fence in the background.

Love the glass railing. Is it set in continuous shoe? Working on this detail right now and curious how you drain deck space over enclosed space.

the decks are tiled, have floor drains in their centres, and another continuous drain in front of the windows as a backup.

The glass is set in to a concrete hob with grout.