Diagonal decking is the technique of installing decking at a 45-degree angle across the joists.  Using diagonal decking increases the strength of the deck frame preventing racking and making installing sway bracing unnecessary.  Depending on the decking material you are using you may need to reduce your joist spacing to 12” on center to help support the diagonal span.  Some deck builders will tell you that applying decking diagonally will increase your waste factor by 15 percent.  We believe you can do much better than that with some planning.  However, more labor is involved because this technique requires you to make more cuts. 

It is usually best to start with the longest board length from a corner and work off of both sides.  It is important to square the decking in order to maintain a consistent angle across the surface.  You can allow the ends of the boards to hang over the frame until the end so you can use a single pass with a circular saw to achieve a consistent edge.  Diagonal decking adds a distinct character to your deck and can be directed to emphasize a view or affect how people move through the space.  For decks that are over 20’ wide you should consider applying your decking diagonally to minimize butt joints.