Building a deck might sound like a fairly straightforward task that anyone can accomplish, but there are a variety of elements that go into the planning stages to ensure the safety of the deck upon completion. While a typical deck under 6 feet in height may only require posts set every 5 to 8 feet, the type of deck, the type of wood, the height of the deck and a variety of other factors can influence the spacing of the support posts.
Size of the Deck
The size of the deck directly affects the spacing of the support posts. While a 16-foot-by-16-foot backyard deck for recreational purposes, such as an outdoor kitchen and general lounging, may only require deck posts spaced every 7 feet, a larger deck may require that the spacing be narrowed down to within 5 feet. Spacing is completely dependent on the size of the deck.
Type of Post
The type of post you use can also affect the spacing between posts. Most backyard decks using wooden posts rely on the 5-to-8-feet average for the post spacing, but modern advancements in deck building now allow for metal posts as well as composite posts to be used in place of traditional wood. Metal posts can support more weight than a wood post, and can thus be spaced out further depending on the deck requirements.
Just as local fire codes can change where your wood stove can be placed within the house in relation to a wall, the local building codes for your city, county and state can determine the actual spacing of the posts for your backyard deck. While the standard of 5-foot spacing can be used to reinforce most decks to an acceptable level, you should check with your local building inspector's office to be sure.
The weight load of your deck also affects the spacing of the posts. For typical decks where only a few family members or the occasional extra guest and backyard patio furniture are expected, the average 5-foot-to-8-foot measurements for post spacing can be used, but if you expect heavy loads of any kind, you will need to contact an engineer as well as your local building inspector to determine the exact spacing.