How far should the toe extend into competent material when keying?

When keying, the toe should extend into competent material by a minimum of 2 feet to ensure stability and support for the structure being built. This depth is critical because it allows for sufficient anchorage within the stronger soil or rock layers, which helps to resist overturning and sliding forces. A toe that reaches this depth can effectively distribute loads and enhance the overall integrity of the foundation.

Keying beyond this depth, such as 3 feet, might not be necessary in all situations and can result in excessive excavation and cost without significantly increasing stability, making the 2-foot minimum a common and generally accepted standard in construction practices. A minimum of 1 foot or 6 inches would not provide adequate penetration into the competent material, potentially compromising the foundation’s reliability and overall safety.