[RAILINGS ALSO REQUIRE ATTENTION
Because railings are the most visible element of a deck, they offer the builder an opportunity for creativity. They can be made of many materials, formed to different shapes and connected in many ways. However, builders must remember that the railing design must adhere to local building codes that are designed to ensure safety. Typically, if a deck is more than a certain distance from the ground, as little as 18 inches in some areas, railings are required for safety purposes. Codes specify a certain maximum opening between balusters, spindles, or pickets so that a 4-inch diameter ball won’t pass through the railing.

The height of the railing is also regulated, with a height of 36 inches standard for residential properties and 42 or 48 inches most common for commercial and fencing applications.
Builders must understand loading and how to properly attach railings.
http://www.nadra.org/consumers/deck_inspections.html

http://www.backyardamerica.com/safe-deck.htm

decks, railings and codes info -
http://www.google.com/search?hl=en&c...-revision&cd=1