What Is a Deck Footing?

Purpose

• Footings are an important part of a deck's foundation that prevent the weight of the deck from causing the posts to sink into the ground. Footings prevent frost from causing deck movement. Also, a deck not properly secured by footings can detach during high winds. The number of footings used depends on the weight of the deck and how often it is subject to high winds.

Types

• With a direct-pour footing, concrete is poured into a hole in the ground and the post is set directly into the concrete. This type works best for locations that have little or no frost, according to the University of Minnesota. With a tube-form footing, a tube form is set into the ground and concrete is poured into the tube. Because a tube form can extend above ground level, the concrete can meet the post above ground. Although one option is to set posts directly into footings, another practice is to use a pier as an upright support to connect the buried footing to the above-ground post. The disadvantage of this design is that it does not provide side-to-side (lateral) resistance in the way that posts embedded directly into a concrete footing do.

Considerations

• The size and depth of deck footings depend on soil conditions and the climate. Footings need to be set below the frost line to prevent deck movement when the soil freezes during winter. This depth ranges from 12 inches in Southern climates to 48 inches or more in Northern climates, according to StartRemodeling.com.

Tips

• To prevent air pockets and promote settling, fill the footing hole with about 1 inch of concrete, use a shovel handle to pack down the concrete and repeat pouring and packing until concrete fills the hole level with the ground. Set a small 2-by-4 board on its edge, with a level on the board, and use a tool called a "screed" to smooth the concrete. Let the footings cure for a few days.