How to Find Depth & Width of Foundation of a Building

Dig close beside the outside of the building. The foundation of a building will sit on footers, which are concrete slabs that support the foundation. Because the footer must support the weight of the building's foundation, it is always wider than the foundation wall. Keep digging until you hit concrete; this is the footer.

Measure from where the concrete foundation starts above ground to where it meets the footer using a tape measure. This will give the measurement of the depth of the building's foundation.

Dig outward from the foundation until you reach the edge of the footing. Measure the width that the footing extends past the foundation wall. Footings are typically constructed with a width equal to twice the thickness of the foundation wall. By doubling the extension you measured to account for the side of the foundation you can't see, you would get the width of the foundation wall.