Deck Post Footings 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.

Deck post footings size.

This is a permanent footing and is great for large or high decks that need very strong footings. Of course you can get a 24 base size and it will spread weight over an even greater surface area. 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.

For aesthetic reasons most deck builders size them all based on the worst case loading. Use added batter boards and string to mark rows of posts. 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. Diameter center footing size and table b3 calls for a 16 in.

Footings typically must extend below the frost line to prevent shifting during freeze thaw cycles. 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. The size and spacing of footings tie directly to the maximum spacing between posts of the beam they support.

A good size for a common backyard deck is a 10 or 12 diameter for the sonotube and a 20 base diameter. 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. 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.

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. Depending on how heavy and high your deck is your concrete footing underground may take 1 4 bags of concrete. Post spacing should be even. My calculations came up with 15 3 4 in.

Step 2 dig footing holes about 6 inches deeper than required. Typical post size is a pressure treated 4 4. 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 between 3 and 14 in concrete.

When the irc leaves us hanging we can often find an alternative rope to climb.