Deck Footing Size Chart

Depending on the type of soil the footing diameter at the base must be a minimum of 12 10 or 9 for the corner post and 17 14 or 12 for all intermediate posts.

Deck footing size chart. Sizing deck footings assuming a minimum soil bearing capacity of 1 500 psf 8 inch diameter concrete piers bearing on square footings measuring 2 feet on a side and 9 to 11 inches thick are adequate for most single story decks where beams are spaced 14 feet apart or less and joist spans are 14 feet or less see table below. A good size for a common backyard deck is a 10 or 12 diameter for the sonotube and a 20 base diameter. A comparison of the footing sizes i calculated for the example deck resting on 1500 psf soil in the sizing deck footings article and dca 6 table b3 shows an almost identical result. The dca 6 table allows joist overhangs cantilevers past the beam of up to one quarter of the span between the beam and the ledger.

We will teach you how to determine the code compliant size of your footings based on the soil type and tributary loads. International code council footing locations are determined by the size of the deck beam and its permitted span. To calculate the load you should use 40lbs per square foot for live loads these are variable loads that are dynamic such as the weight of. The number of footings needed to support a deck beam is dictated by the beam s size.

Call 811 before digging. Once your deck has been laid out and the framing has been planned out it s time to begin installing posts. Check out our deck footing frost map to help you understand how deep your footings will need to be excavated. Use this calculator to find out the beam span and deck footing size for your project.

As shown above the maximum span for a double 2x8 beam supporting 14 foot joists is 5 feet 9 inches. This illustration shows some common ways to configure deck beams. Deck footing size chart. Diameter center footing size and table b3 calls for a 16 in.

Calling the dig line before beginning can prevent the possibility of cutting underground utilities. My calculations came up with 15 3 4 in. Installing foundation footings posts. The one down side to this is the extra digging involved.

Of course you can get a 24 base size and it will spread weight over an even greater surface area. Be sure to have your joist span calculations ready to enter for an accurate reading and check out our concrete calculator to determine the size of your footings total linear feet of railing. In order to determine the proper size for your footings you will need to establish how much total weight they are going to have to support and what kind of soil they are covering. View the pdf below to get more detailed information about acceptable deck beam and footing sizes.