Joist Span

• Joists are the horizontal sections of framing material that extend from a foundation structure in the yard to a ledger board on the side of a house. They serve as the substructure for the flooring planks of a deck. The maximum distance you can safely span deck joists depends on multiple factors, including the type and size of lumber or other material you are using for the joists. In general, however, the distance you can safely span joists increases as the spaces you leave between adjacent joists decreases.
  
  

Flooring Pattern

• Traditional deck designs require that you place flooring planks on top of joists using a linear, unilateral pattern. The resulting floor features planks that all flow in the same direction and that are parallel or perpendicular to the adjacent home. Alternately, you could set flooring planks at an angle so that they are unilateral but diagonal in orientation. More complex deck flooring pattern options include utilizing basket-weave and herring-bone designs, both of which feature planks flowing in multiple directions.
  
  

Levels

• Most decks are one-level or single-tiered, which means they consist of single, elevated platforms. However, you can also design a deck to have two or more levels. Decks with multiple levels are particularly useful in backyards that are sloped or hilly, as they can help tie uneven landscape elements together. In addition, each level of a multi-level deck can provide a different function. For example, one level can be for dining, while another can be for lounging or sunbathing.
  
  

Railings

• Regardless of how many levels a deck has, if a deck's surface is 30 inches off of the ground or higher, a railing that is a minimum of 36 inches high is required. If a deck's surface is higher than 5 feet, 10 inches from the ground, the deck's railing must be at least 42 inches high.
  
  

Shape

• A standard deck has a simple, rectangular shape, which helps maximize usable deck space. In comparison, decks with more complex shapes can help increase aesthetic appeal. A hexagonal deck, for example, provides six linear sides that you can use for highlighting specific items. For example, you can place a grill against one of the deck's sides, a plant against another and a lawn chair against another.