Deck Post Footings Size

Post spacing should be even.

Deck post footings size.

This is a permanent footing and is great for large or high decks that need very strong footings. The number of footings needed to support a deck beam is dictated by the beam s size. 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. Step 3 fill the bottom of the hole with 6 inches of gravel and compact the gravel with a 2x4 or wood post.

For aesthetic reasons most deck builders size them all based on the worst case loading. 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. Step 2 dig footing holes about 6 inches deeper than required. Once you decide the distance measure from the house for the first row of boards.

The evolution compression post base will make any deck footing look fantastic because the connection mechanism is completely hidden deep. There is little material cost to a buried post footing. Diameter center footing size and table b3 calls for a 16 in. The size and spacing of footings tie directly to the maximum spacing between posts of the beam they support.

The american wood council publishes the prescriptive residential wood deck construction guide which is based on the international residential code irc. A larger beam can span a greater distance requiring fewer but larger footings. 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. Deck footing size chart.

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. 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. Typical post size is a pressure treated 4 4. A good size for a common backyard deck is a 10 or 12 diameter for the sonotube and a 20 base diameter.

When the irc leaves us hanging we can often find an alternative rope to climb. Unless the deck requires engineering i refer to a beam span table as i design the framing. Depending on how heavy and high your deck is your concrete footing underground may take 1 4 bags of concrete. Footings typically must extend below the frost line to prevent shifting during freeze thaw cycles.

This is between 3 and 14 in concrete.