The short answer is yes. If you are installing, replacing, or structurally modifying a permanent commercial sign anywhere in the St. Louis area, you should assume a permit is required until the local authority tells you otherwise. That said, the longer answer is where hard-working business owners get tripped up, because “St. Louis” is not one government. When talking about sign permits in this region, one must come from two directions- the City of St. Louis and St. Louis County, which are two entirely separate jurisdictions with two entirely separate processes.
Why “St. Louis” Means Two Different Governments
The City of St. Louis formally separated from St. Louis County in 1876, and the two have operated independently ever since. The City is an independent city with its own building code, its own zoning ordinances, and its own permit office. The County, meanwhile, contains more than 80 individual municipalities, each of which is free to write and enforce its own sign code. It is clear, then, that the first question in any sign project is not what the sign will look like. The first question is whose rules the sign must follow.
Sign Permits in the City of St. Louis
Inside the city limits, sign permits run through the City of St. Louis Building Division. If you are installing a new sign or modifying an existing one on your property or building, the City requires a building permit to confirm the sign meets local safety and zoning rules. Three additional wrinkles are worth knowing. First, illuminated signs typically require a separate electrical permit pulled by a licensed electrical contractor. Second, properties in historic districts or special business districts often face an added layer of design review, which can add weeks to the timeline. Lastly, banners attached to City light poles are handled by an entirely different office, so a banner permit will not cover a building sign and vice versa.
There is genuinely good news on this side of the line as well. In early 2026, the City launched a new online permit portal that allows applicants to submit plans, pay fees, and track their permit status without spending a day at City Hall, making the process considerably faster than it used to be.
Sign Permits in St. Louis County
The County side must also be approached from two directions. The first direction is unincorporated St. Louis County, where the Department of Transportation and Public Works reviews and issues sign permits directly. The County even publishes its own commercial guide to sign building permit requirements, which is the correct starting point for any project outside municipal limits.
The second direction is the municipalities themselves- Clayton, Chesterfield, Kirkwood, Florissant, and dozens more. Each municipality sets its own rules on size, height, and illumination, and often times a sign that sails through approval in one suburb would be rejected outright two miles down the road. To complicate matters further, some municipalities handle their own sign approvals while still routing electrical and mechanical permits through St. Louis County Public Works. Identifying your exact municipality is therefore step one, step two, and step three.
What Happens If You Skip the Permit
Skipping the permit is a false economy. Businesses that install unpermitted signage face fines, forced removal orders, and stalled occupancy approvals, and the sign itself may need to be taken down, re-engineered, and re-installed at the owner’s expense. We covered the broader risks in our guides to signage permits and the cost of non-compliance, but the principle is simple: an unpermitted sign is a liability hanging over your storefront, making it much harder for your business to operate with confidence.
How Piros Signs Handles Permitting for You
Piros Signs has been navigating St. Louis area sign codes since 1957. We are licensed, we are insured, and we treat permitting as part of the job rather than as your problem, handling the research, the drawings, and the applications for every sign we design and fabricate and install. Whether your project sits in the City, the County, or one of the surrounding communities in our service area, our team will identify the jurisdiction, secure the approvals, and put your sign up correctly the first time.
Request a quote online or call us at (636) 464-0200 to start your project on the right side of the rules.