The number of posts or footings needed for your deck depends on its size, shape and structure. Generally, you’d need at least one post or footing at each corner of the deck, and additional posts spaced evenly along the outer edges for support. The exact number can vary based on local building codes and the dimensions of your deck.
Starting with your perimeter of deck, mark the location of each deck post or footing to locate the fitting position. In general, posts (footings) need to be spaced no more than 8 feet apart. Some builders position them every 4 to 6 feet for a completely rigid frame.
There are different types of deck like attached deck which are attached to your walls of house which require less number of posts or detached/ floating deck which isn’t connected directly to the house. It’s connected to the home through a pathway or walkway and require more posts for support.
If you’re spacing the posts for your 12×20 deck at 6′-8″ intervals for longer side and at 4 feet intervals for shorter side, you would have four posts along each of the longer sides (20 feet) and three posts along each of the shorter sides (12 feet). This results in a total of 12 4×4 posts for your 12×20 deck.
How many posts do i need for my deck
The number of posts needed for your deck depends on various factors such as the deck size, height, joists size and local building codes. As a general guide, you might need at least four posts for a basic deck.
Typically for a 10×10 attached deck, you’ll need at least 3 4×4 posts, plus at least 2 more if you’re planning on building stairs with it. If your deck will be a different size, it’s easy to figure out how many posts you’ll need.
In general, you will need at least 9 4×4 posts for a 12×12, 10×12, and 12×16 floating deck, while for a 12×20, 16×20, or 16×16 floating deck, you’ll need at least 12 4×4 posts. In addition, you’ll need at least 8 4×4 posts for a 10×10 deck.
Here’s are table to find out how many posts you’ll need for different size deck:-
| SL.no. | Type of Deck | Size of Deck | No. of Posts |
| 1 | Floating Deck | 10×10 | 8 4×4 posts |
| 2 | Floating Deck | 10×12 | 9 4×4 posts |
| 3 | Floating Deck | 12×12 | 9 4×4 posts |
| 4 | Floating Deck | 12×16 | 9 4×4 posts |
| 5 | Floating Deck | 12×20 | 12 4×4 posts |
| 6 | Floating Deck | 16×20 | 12 4×4 posts |
| 7 | Floating Deck | 16×16 | 12 4×4 posts |
| 8 | Attached Deck | 12×12 | 3 4×4 posts |
Conclusion:-
The number of posts needed for your deck depends on various factors such as the deck size, height, joists size and local building codes. As a general guide, you might need at least four posts for a basic deck.