Do I need a permit for excavation in Missouri?
Missouri has no statewide excavation permit, so whether you need one depends on your city or county and on the work. Foundation digs, utility connections, and grading that changes drainage usually require a permit, and every dig requires an 811 locate request at least two full working days before you start.
In unincorporated Jefferson County, the Code Enforcement Division at (636) 797-5310 will tell you whether your project needs one. Inside city limits, ask that city's building department instead.
Which jobs need a permit?
The kind of work triggers a permit, not the size of the hole.
| Work | Permit usually needed? | Note |
|---|---|---|
| Foundation, basement, or retaining wall | Almost always | Building permit, inspected before it is covered; walls over a specified height |
| Grading that changes drainage | Often | Can require a grading permit |
| Earthwork in or near a flood zone | Yes | Additional floodplain review |
| Water or sewer connection | Yes | From the water authority or municipality |
| Commercial site work | Almost always | Inspections at multiple stages |
| Minor landscaping and grading | Typically not | Unless it changes drainage significantly |
| Utility potholing and daylighting | Generally not | Investigative work, not construction |
| Fence post holes | Not for the digging | The fence itself may need one |
| Any dig at all | Not a permit | 811 locate request required |
"Usually" and "generally" matter here. The only sure answer comes from the building department, given your address and what you plan to do.
Is calling 811 the same as a permit?
No. Calling 811 before any excavation in Missouri is required by state law, for a homeowner setting fence posts as much as a contractor trenching. Utility owners then mark their lines with flags and paint. A permit is a separate approval from your city or county. Most small jobs need 811 and no permit; bigger jobs need both.
When can I dig after calling 811? Missouri law requires notice at least two full working days before you dig, counted from the day after you call. Missouri 811 describes this as three working days. A working day is a weekday that is not a holiday. For example, call on a Monday and the earliest legal dig day is Thursday, once the area is marked.
City or county: who do I call?
Festus, Arnold, Hillsboro, Crystal City, DeSoto, and the other cities in Jefferson County each run their own building department. If your address is inside city limits, the city governs your project. If it is unincorporated, call the Jefferson County Code Enforcement Division at (636) 797-5310 with your address and a plain description of the work. Not sure which you are? Look up your address on the Jefferson County Assessor's website; incorporated addresses show the city name.
In a flood zone, such as parts of the Meramec River drainage, any filling, grading, or digging needs extra floodplain review. Check before you dig.
What if I skip a permit I needed?
- Reopening the work. You may have to dig it back up for inspection before it can be legalized.
- Removal and redo. If it cannot be inspected in place, you may have to tear it out and rebuild it.
- Insurance. Policies typically exclude structural failures in unpermitted work.
- Selling the house. Unpermitted structural work can show up in title searches and stall a sale.
A neighbor skipping a permit does not mean you can. The risk sits with the property owner, and a contractor who suggests skipping one is handing that risk to you.
Who pulls the permit?
On permitted work, a licensed contractor like J1S pulls the permit for you and includes the cost in the quote. Look for "permits included as required" in any quote; silence on permits is a question to ask. For scope and pricing, see the Missouri excavation cost guide, and for trench work, the utility trenching guide.
Common questions
Does J1S pull permits for its work?
Yes, for work that requires it. J1S is licensed and insured in Missouri, and permit costs are included in the project quote when applicable. You won't be handed a permit application to figure out on your own.
Do I need a permit just to call 811?
No. 811 is not a permit. It is a required utility notification, it is free, and the request must be made at least two full working days before you dig. It has nothing to do with building permits, so a project that needs both needs both.
What if I dug without a needed permit?
At minimum, you'll need to get a retroactive permit (if available) and likely open the work back up for inspection. In some cases, completed work must be removed and redone. Beyond the immediate cost, unpermitted structural work can void homeowner's insurance and create title problems when you sell.
Is there a minimum size for a permit?
There's no universal minimum depth or cubic yard threshold. The trigger is the nature of the work, such as a utility connection, structural work, or grading that changes drainage, not the size of the hole. When in doubt, call the Jefferson County Code Enforcement Division at (636) 797-5310.
Sources
- Missouri Revised Statutes, Section 319.026: state law requiring notice to the one-call center at least two working days before excavating.
- Missouri Revised Statutes, Section 319.015: the state definition of excavation covers digging and augering with any tools, and defines a working day as a weekday that is not a holiday.
- Jefferson County, Code Enforcement: the county division that regulates construction in unincorporated Jefferson County and issues building permits.
- Jefferson County, Floodplain Development Permit Application Process and Checklist: a floodplain development permit is required for filling, grading, or excavating in a special flood hazard area.