Pole Barn Permits in Calvert, St. Mary's & Charles County: What You Need to Know

Pole Barn Permits in Southern MD

A pole barn is one of the most cost-effective ways to add storage, workshop, or agricultural space to your Southern Maryland property. But before you pour a single post, there's a permitting process to navigate — and it looks different depending on which county you're in. Calvert, St. Mary's, and Charles County each handle pole barn permits a little differently, and getting it wrong can mean stop-work orders, fines, or a structure you have to modify after the fact.

Here's a breakdown of what each county typically requires, so you know what to expect before you call your contractor.

Calvert County

In Calvert County, pole barns fall under the accessory structure rules in the county's zoning ordinance, which specifically lists pole barns alongside garages, gazebos, and pool houses as examples of accessory structures. As of recent zoning updates, a building permit is required once an accessory structure reaches 200 square feet — smaller structures may be permit-exempt under the revised rules, which also raised the size threshold to reduce permitting costs for homeowners.

There's an important exception, though: if your property falls within Calvert's designated Critical Area — the environmentally protected zone near the Chesapeake Bay, its tributaries, and other waterways — a permit is required regardless of size. Given how much of Calvert County borders water, this is worth checking before you assume your build is small enough to skip the process.

If you're hiring a contractor, Calvert County also recommends verifying that they hold an active Maryland Home Improvement Commission (MHIC) license before signing anything. Building it yourself doesn't require a licensed contractor, but the permit and zoning requirements still apply either way.

Who to contact: Calvert County Planning & Zoning, Division of Inspections and Permits.

St. Mary's County

St. Mary's County draws its permit line at structure size. Small, one-story detached accessory structures — the kind of small storage building many homeowners start with — can be exempt from a building permit if they stay under the county's floor-area threshold and aren't located in a flood plain. Once a pole barn exceeds that threshold, both a building permit and a zoning permit typically come into play, along with inspections for larger structures.

Even when a project qualifies for a building permit exemption, a separate zoning permit is usually still required. That zoning review is what checks your setbacks, confirms you're clear of Critical Area and forest conservation restrictions, and verifies compliance with stormwater management rules — so "no building permit needed" doesn't mean "no permit needed at all."

Because exemption thresholds and fees are the kind of detail that gets revisited by the county periodically, it's worth confirming the current square footage cutoff directly with the permitting office rather than relying on what a neighbor's shed needed a few years ago.

Who to contact: St. Mary's County Department of Land Use and Growth Management.

Charles County

Charles County takes the most zoning-forward approach of the three: a zoning permit is required for a pole barn of any size, even the smallest ones. A building permit becomes necessary once the structure crosses the county's size threshold, and setback rules apply on top of that — accessory structures like pole barns generally need to sit at least six feet from side and rear property lines, and they aren't allowed in the required front yard at all.

Because Charles County requires zoning sign-off no matter how small the structure is, this is the county where skipping the paperwork on a "just a small pole barn" project is most likely to catch homeowners off guard.

Who to contact: Charles County Department of Planning and Growth Management, Codes, Permits, and Inspection Services.

What's Consistent Across All Three Counties

Regardless of which county you're in, a few things hold true everywhere in Southern Maryland:

Permitting and inspections fall under the Maryland Building Performance Standards, which incorporate the International Building Code and International Residential Code with state-specific modifications.
Setback, lot coverage, and placement rules are enforced locally, even when the structure itself is exempt from a building permit.
Critical Area regulations near waterways can require a permit even for structures that would otherwise be exempt by size.
Adding electrical, plumbing, or a permanent foundation typically triggers additional trade permits beyond the base building or zoning permit.
Requirements and size thresholds get updated periodically at the county level, so current rules should always be confirmed directly with the local permitting office before you finalize plans.

Let Backroad Construction Handle the Details

Permitting is one of the most overlooked parts of a pole barn project — and one of the easiest to get wrong if you're not familiar with your specific county's process. At Backroad Construction, we build pole barns throughout Calvert, St. Mary's, and Charles County and work through the permitting requirements as part of every project, so you don't have to figure out zoning ordinances on your own.

Ready to start planning your pole barn? Contact Backroad Construction today for a free estimate, and we'll walk you through what your specific property and county will require.

Note: Please double check the permitting rules in this article prior to beginning your project because these rules change often.

Here are the links to some official sites:
Calvert County

Accessory Structure info page: https://www.calvertcountymd.gov/2971/Accessory-Structure
Zoning Ordinance, Article 19 (Accessory Structures): https://ecode360.com/46250317Z
Critical Area info: www.calvertcountymd.gov/CriticalArea
Zoning details: www.calvertcountymd.gov/Calvert-County-Zoning

St. Mary's County

2026 Building Permit Guide (third-party summary, useful overview but verify against the county directly): https://www.jaspector.com/resources/permits/maryland/st-marys/
Permits (Permit Services Division): https://www.stmaryscountymd.gov/lugm/Permits/
Department of Land Use & Growth Management (main dept page, with contact info): https://www.stmaryscountymd.gov/lugm/
Phone: 301-475-4200 ext. 1500 · 23150 Leonard Hall Drive, Leonardtown, MD 20650

Charles County