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How to Calculate Pier Footing Size

Deck piers are long stretches of pathway elevated above soil or water. Pier footing is constructed at the base of pier support legs and submerged under soil. Footing is made out of concrete and acts as the central base of the pier. Each footing is molded into a concrete square around the bottom of the pier support leg. Footing absorbs the weight load of the pier and distributes it outward to keep the pathway sturdy and balanced.

Things You'll Need

  • Measuring tape
  • Calculator
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    • 1

      Measure the width of a pier platform beam. Standard pier platform beams are 2 inches by 8 inches or 2 inches by 12 inches.

    • 2

      Identify the thickness of the footing by determining the width of the pier platform beam. For example, if the platform beam is 12 inches wide, the footing must be 12 inches thick.

    • 3

      Double the width of the platform beam to calculate the total width of the footing. For example, a platform beam measuring 12 inches wide requires a 24-inch by 24-inch footing. Therefore, a pier with 12-inch wide platform beams requires a footing on the bottom of each support post measuring 12 inches thick and 24 inches by 24 inches.