Most residential basements are 8 to 10 feet deep. You can dig deeper depending on building codes, but it does become more difficult. You’ll likely need to install stronger foundation walls and additional supports to handle the increased load. Depending on the water table, you may also need a water management system. Clay soil can support a deeper foundation than sandy soil. A structural engineer will be able to tell you the maximum, feasible depth.

A crawl space can be as little as 42 inches below the grade of your house, but this is not always recommended in flood-prone areas. At a minimum, there must be at least 16 inches of clearance between the ground and the floor joists to access the space in an emergency.

The best method for digging a trench depends on the scope of the project. For a short, shallow trench (less than 2 feet deep) in light, soft soil, digging by hand may be sufficient. However, digging by hand is labor-intensive, so consider the effort required. A machine trencher is the better option for longer trenches (over 100 feet), deeper ones, or when dealing with difficult soil conditions, such as rocky or hard ground, or obstructions like tree roots. A machine can save significant time and energy in these situations.

If you’re planning to dig on your property, you’ll need to check for underground utility lines. Call the national call-before-you-dig 811 number. Once connected to an operator, you can schedule a site visit to mark underground lines. This way, you won’t accidentally dig into pipes and can cause major (read: costly) issues.