How to Find Out How Deep Footings Are

Obtain a copy of a building's blueprints. The footing specifications are detailed on the building blueprints. The footing depth can be measured on the prints by an architect's scale, if they're not specifically mentioned in a detailed note.

Obtain a copy of local building codes from the municipal planning office that oversees building and construction permits, or from a local office of a professional organization such as the National Association of Builders and Contractors. (Resource 2) The local building authorities will be able to tell you the footing specifications for the geographic area. Footing specifications will vary based on geographic topography and building size. For example, a single-story residential building built in an agricultural setting will have different design requirements than a four-story commercial building built along a river bank.

If the informational resources aren't available, or if it's not possible to get a measurement from blueprints, you can simply measure the footings. Use multiple pieces of threaded rod connected with threaded connectors. Footings are located at the bottom of foundation walls. They're shaped like an inverted "T." In other words, the foundation wall is built vertically on top of a wider concrete pad buried at the bottom of the wall.

Insert the threaded rod vertically into the ground, following the foundation wall downward as a guide. Use threaded couplings to join together shorter pieces of rod. The rod will stop when it bumps into the footing at the bottom of the wall. Mark the point on the rod that's even with ground level, and then pull the rod out of the ground.

Measure the length of the rod from your mark to the tip that was inserted into the ground. To verify your measurement, repeat this procedure in two or three locations along the foundation.