Simple pier-and-grade-beam foundations can support decks, porches, pole barns, and small home additions.

Sonotubes, placed on pier footings with a pressure-treated grade beam, can be installed easily without disturbing existing utility lines.
Sonotubes, placed on pier footings with a pressure-treated grade beam, can be installed easily without disturbing existing utility lines.

Sizing Piers 

For sizing pier diameters for small foundations, the rule of thumb is “1 inch per foot of span.” Thus, a deck that spans 8 ft. will stand comfortably on 8-in.-diameter piers, while a deck that spans 10 ft. requires 10-in.-diameter piers. For spans longer than 12 ft., add a second row of piers and a second girder at the center of the joist span.

For calculating concrete amounts, see Estimating Concrete for Piers.

For more building decks and simple pier foundations, visit the JLC Field Guide.