As mentioned above you can make your own materials by using the "Create Material" option from within PlusSpec. This is one of PlusSpec's most powerful features.
See my other posts on this here viewtopic.php?f=12&t=371&p=1138#p1138
and here viewtopic.php?f=15&t=318&p=2063#p2063
for additional information.
As a further example, attached is a "Shadowclad" ply panel I created... Shadowclad is a range of Plywoods from Carter Holt Harvey (CHH) in New Zealand. I modeled an accurate panel complete with face grooves and weather/joint grooves to show how detailed your self created materials can be. This panel shows accurately in a Takeoff/BOQ.