If you build any decks, you should know about the DCA 6. It’s the document that your local building department—if they have their heads screwed on straight—probably base their codes on. Or, they just use the DCA 6 whole cloth.
If you build a lot of decks every year, being able to bounce through all the many aspects of DCA 6 with aplomb—as well as comparing it to IRC codes—may well be of service to your business. And it’s free.