Construction of decks requires permitting. On simple rectangular decks, most times either the "Single Joist Span" or "Multi-Joist Span" permit packets are sufficient to get your project evaluated and permitted.
On anything that isn't a simple rectangular design or all the information cannot be submitted via one of the two permit packets, a building permit application needs to be filled out. Along with a plan view drawing of the proposed decks structure as well as a simple cross section showing the structural member sizes. These drawings should include: Ledger locations & sizes; joist size, spacing, and span; beam sizes and spans; post sizes and locations; footing sizes, locations, & depth.
Deck Footing Design Calculator. (*Note: without additional information, we assume soil bearing capacity for residential projects at 1500 lbs per sq. ft. Residential deck superstructures are to be designed to carry a 50lb per sq. ft. load)