Deck Post Footings Size

Typical post size is a pressure treated 4 4.

Deck post footings size.

Unless the deck requires engineering i refer to a beam span table as i design the framing. The number of footings needed to support a deck beam is dictated by the beam s size. Depending on how heavy and high your deck is your concrete footing underground may take 1 4 bags of concrete. The size and spacing of footings tie directly to the maximum spacing between posts of the beam they support.

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. When the irc leaves us hanging we can often find an alternative rope to climb. Post spacing should be even. In this case though i couldn t find a current source with a table that shows allowable tributary areas for various sizes and wood species of posts.

The american wood council publishes the prescriptive residential wood deck construction guide which is based on the international residential code irc. Diameter center footing size and table b3 calls for a 16 in. Step 3 fill the bottom of the hole with 6 inches of gravel and compact the gravel with a 2x4 or wood post. This is a permanent footing and is great for large or high decks that need very strong footings.

A larger beam can span a greater distance requiring fewer but larger footings. Step 2 dig footing holes about 6 inches deeper than required. My calculations came up with 15 3 4 in. 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.

Use added batter boards and string to mark rows of posts. Footings typically must extend below the frost line to prevent shifting during freeze thaw cycles. The evolution compression post base will make any deck footing look fantastic because the connection mechanism is completely hidden deep. Once you decide the distance measure from the house for the first row of boards.

Post spacing is going to depend on your design local building codes the size and length of your beams and the size of your posts. For aesthetic reasons most deck builders size them all based on the worst case loading. Of course you can get a 24 base size and it will spread weight over an even greater surface area. Deck footing size chart.

There is little material cost to a buried post footing.