Pier Foundation Sizes

Piers

• A pier is a concrete structure buried in the ground. Once a hole is dug, it's often filled a few inches with gravel or other rough-cut rock. The pier is then carefully fitted into the hole. The size of the hole varies with ground condition and the size and weight of the house, but generally speaking, it's normally 16 inches in diameter. The larger or heavier the home, the larger the hole should be.

Pier Sizes

• A pier contains a concrete footing and an attached vertical concrete “pillar.” These structures bear the brunt of the weight of the house. Therefore, their sizes and compositions are crucial to a successful foundation structure. In general, the typical base footer is a 16-inch square about 8 inches thick, which would be good for a small ranch, cabin or bungalow, ranging between 900 and 1,500 square feet. Larger homes use more piers, and footers are larger to support the extra weight. Some footers are as large as 30 inches to support multi-storied homes. Alternatively, larger structures can simply use more piers buried closer together.

Figuring the Pier Size

• The length of the floor and beam determines the size of the pier. Almost always, the longer the beams and joists, the larger the pier must be to support it. This is based on the idea that the larger beam and joist means a larger house with more weight to support.

Pier and Beam Variation

• The size of the pier is closely related to the size of the house and the beams it uses to support the floor. Building a home with a 10-foot floor support sitting atop a 12-foot beam necessitates a footer of about 21 inches in diameter. The greater the weight and span of the wood, the larger the pier. If you go larger and use an 18-foot joist that sits on top of a smaller 10-foot beam, then the size of the pier should increase to about 25 inches around. The real issue is the support of the beam. The beam is doing most of the work and supporting the weight. Therefore, the size and strength of the beam is more important in determining the size of the pier than the floor supports.