Building rules vary, but most require a railing on decks that are higher than 24 inches from the ground. It is usual to have a railing height requirement of 36 inches. Railing posts can be fastened to the perimeter joists' outer faces or through posts supported by the footings. The former method is called outside post-and-beam construction and the latter inside post-and-beam construction. Decks without rails can be dangerous because people may believe they can walk off the edge. Even with rails, decks are still subject to damage and deterioration due to environmental factors such as heat, cold, rain, snow, and sunlight. Weather conditions can also affect how a deck performs its safety function. For example, if a deck is exposed to freezing temperatures, it might become difficult or impossible to climb onto it. Deck boards are available in a wide variety of shapes and sizes, so you should choose ones that will fit your home and your needs. Larger decks tend to be better for family use because everyone has something to contribute. Smaller decks are useful for more privacy. Be sure to check your local building codes before you start work on your project.