"jdguay" wrote in message
I am trying to determine how much and what sizes of lumber I need. My
big question is deck boards. The deck is just over 18 feet wide, and
the longest 5/4x6 deck boards I can get are 16 feet.


"Just over" is going to create a PITA. If exactly 18' you can use various
combinations of 8, 10, 12, 16 to get there with almost no waste.

Personally, I'd rethink the size if you have not started yet and either
scale back to 16', go up to 20', or at least stop at an even 18'. With
even 18' you can go with 12 & 6, then 6 & 12, then 8 & 10, etc.