How to Build Deck Footings

Updated February 21, 2017

The benefits of a well-built backyard deck are immeasurable. But, as you'll find out, there's a lot of time and labour that goes into making your deck solid. It all starts with the bottom. This article will provide you all the know-how you need to create first-class footings for your backyard oasis.

Call the local utility company before you touch shovel to ground. They can mark the areas around your dig site where electrical, gas and water lines are buried.

Get below the frost line. In colder areas, frost lines are deeper than in more temperate climates. Because you are creating the base for your deck, you want to make sure that the footings you pour are appropriately deep enough for your area. Footings that are too shallow could cause your supports to heave and virtually destroy the entire structure.

Measure off the dimensions, starting with the area you want the deck to cover. You'll need to measure it out and mark where you want your footings to be. Depending on the size of the deck, you'll have anywhere from four to eight footings. Figure this out in advance so that you don't dig footings that are unnecessary. Place ground spikes on all four corners of your measured out deck. Then run a string from spike to spike. This will give you a good idea of the shape of the deck. Your footings should be dug just to the inside of your spikes.

Start digging. Most likely, you'll encounter rocks, roots and clay soil along the way. You can alternate between the spade and a post hole digger, if you have one. It breaks the monotony and makes digging a little quicker. Make your holes wide enough to hold a concrete tube. Choose the tube based on the size of your deck.

Insert your tubes to the desired depth. If they sit above the ground, that's OK. You can cut them so they are flush if you'd like. Before you go to the next step, make sure that your tubes are vertically and horizontally level.

Fill your tubes with concrete. You can premix the concrete if you'd like, but you don't need to. Ground has a certain amount of moisture that the dry concrete will absorb and then harden with. You'll want to add additional water to make sure that you don't have sections of powder concrete, but don't make it too "soupy." Fill your footing to the top. Filling a footing half way and then finishing it off at a later date could cause the footing to split in half.

Add post support to your concrete footings so that you can attach your deck structure to the footings. You can get a long bolt and insert it into your wet concrete so that it hardens in to the mixture. Just make sure that the bolt is level, sticking out about 6 inches. Or you can buy post holders (recommended). These have a small metal post that goes down in to your wet concrete, another that goes up in to your post, and outer brackets to hold the post in place.


Never dig without first having the utility company come out and mark for lines. Always dig your footings to the recommended frost level in your area. Make sure you square off your footings.

Things You'll Need

  • Cement tubes (amount will vary based on the size of your deck)
  • Cement (amount will vary based on the number and depth of your footings)
  • Shovel
  • Post hole digger
  • Work gloves
  • Tape measure
  • String
  • Ground spikes
  • Level
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About the Author

Patrick Cameron is a freelance writer with 10 years of diverse experience in consumer goods branding, promotions and retail communications. He works out of his home in Denver, Colo. He received his Bachelor of Arts in mass communication from the University of Minnesota.