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Pillar Guide
Conex Box in Maryland: A Complete Guide for Maryland Buyers
Conex box, shipping container, storage container: the words get used interchangeably. What changes from one Maryland order to the next is the size, the grade and the delivery route.
The word conex (sometimes spelled CONEX) is short for "container express," a term coined by the United States military in the 1950s for a standardized steel shipping container used to move equipment and supplies during the Korean War. The original CONEX boxes were 8.5 feet by 6 feet by 6.8 feet, much smaller than today's intermodal units, but the principle was identical: a stackable, lockable, weatherproof steel box that could move by truck, rail, or ship without unpacking.
By the late 1960s the commercial shipping industry had standardized on 20-foot and 40-foot intermodal containers, the units you see on every cargo ship and rail line today. The military term stuck in everyday speech. Many people still call any large steel storage box a conex, even when the unit is technically an ISO shipping container or a purpose-built storage container.
Conex Box vs Shipping Container vs Storage Container
The vocabulary lines up like this:
Conex box. Originally a military-spec container. In modern use, a colloquial name for any steel shipping container used for storage. Most commonly applied to 20-foot and 40-foot units in residential and contractor settings.
Shipping container. The technical term for an ISO-standard intermodal container. These are the units that cross oceans on cargo ships. They are built to ISO 1496 specifications, which dictate dimensions, lifting points, and structural strength.
Storage container. A general retail and rental term used by ground-storage companies. Often refers to the same intermodal unit, but the phrase also covers purpose-built ground-level containers that have never seen ocean service.
If you are shopping for storage, the difference rarely matters.
Standard Conex Box Sizes
There are three standard sizes:
20-foot standard. Length 20 ft, width 8 ft, height 8 ft 6 in. Interior floor about 19 ft 4 in by 7 ft 9 in, with 7 ft 10 in of height.
40-foot standard. Length 40 ft, width 8 ft, height 8 ft 6 in. Roughly 2,350 cubic feet, double the 20-foot. Best for contractors, farms, and businesses.
40-foot high cube. Length 40 ft, width 8 ft, height 9 ft 6 in. The extra foot of headroom adds about 350 cubic feet of usable space, which matters when you store racked goods or tall equipment.
Specialty sizes (10-foot, 45-foot, refrigerated, double-door, side-opening) exist but are less common.
Common Uses by Industry
In Maryland, containers can serve these industries:
Construction and renovation: Baltimore rowhouse rehabs, infill lots in Montgomery and Prince George's counties and new homes in Frederick and Howard counties, where tools and materials stay locked on site between phases.
Agriculture: grain, poultry and produce farms on the Eastern Shore and in Frederick and Carroll counties, for feed, seed, fencing and equipment parts kept dry near the fields.
Marine trades: marinas, boatyards and waterfront contractors around Annapolis, Kent Island and the Bay's tidal rivers, for sails, hardware and off-season gear.
Warehousing and manufacturing along I-95, I-70 and the Baltimore harbor, for overflow inventory, packaging and maintenance parts beside the building.
Schools, churches, youth sports leagues and event organizers, for equipment used one season and stored the next.
Common uses:
Tool, chemical, and equipment storage at working yards. Steel walls, lockable doors, and on-site placement make a conex a practical substitute for a built shed, a fenced compound or a temporary office.
Weather-event storage for documents, heirlooms, and inventory.
Construction jobsite storage on long-cycle builds.
Acreage and farm storage. Permanent storage for the things a garage or barn cannot fit.
How to Choose the Right Conex Box
Three questions narrow the decision quickly:
How much space do you need? List what you intend to store. A 20-foot unit works for household goods during a renovation, materials for a residential framing job, or a few pallets of stock. A 40-foot unit doubles that. Compare the list with the container dimensions before you choose.
How clean does the interior need to be? If you are storing tools, equipment, or boxed goods, a used wind-and-water-tight unit is fine. If the unit will be converted to an office, a workshop, or a clean storage space, a one-trip unit saves the cost of repainting and floor refinishing later.
How long will you use it? For a project that ends in a few months, compare the cost of renting from a rental company with the cost of buying. Our rent vs buy guide walks through the crossover math.
How Delivery Works in Maryland
Container One offers Tilt Bed and Customer Assist delivery. With Tilt Bed, the trailer tilts back and the container slides off without help from you. Customer Assist requires an anchor point on your site: a chain connects the container to it, and the container slides onto the ground as the trailer pulls away. Delivery follows this sequence:
Site check. You confirm the access route, the placement spot and the overhead clearance before delivery. A 20-foot delivery needs 110 feet of straight clearance. The truck needs at least 15 feet of height to drive, at least 22 feet of height along the entire unloading path, and at least 10 feet of width. A 40-foot delivery needs 130 feet of straight clearance.
Surface check. Concrete, asphalt, gravel, hard-packed dirt, and grass all work. Soft, waterlogged, or steeply sloped ground may need preparation.
Final placement. The driver sets the container down on the prepared spot.
Container One's Delivery/Dispatch department contacts you to schedule each delivery. Delivery areas across Maryland:
Baltimore, Annapolis and the Western Shore of the Bay, from Harford County south to St. Mary's County
Frederick, Howard, Carroll, Montgomery and Prince George's counties and Western Maryland
The Eastern Shore, from Cecil County south to Worcester County
Permits and Local Rules
Permit requirements depend on city regulations inside city limits and county regulations outside city limits. Before ordering, check with your local building or planning department, and verify HOA rules if they apply. The permit guide for this state covers the questions to ask: container permits in Maryland.
What a Conex Box Costs in Maryland
Pricing is ZIP-specific, because delivery is part of the price. Maryland delivered pricing: starting at $2,067 for a 20ft Wind and Water Tight container delivered in Baltimore. Prices as of October 14, 2026.
If you would rather spread the cost, rent-to-own is available through a third-party partner, My Container Rental.
Frequently Asked Questions About Conex Boxes
Check whether the truck has enough space to unload at the proposed location: Container One requires 110 feet of straight, unobstructed space for a 20ft container and 130 feet for a 40ft container, at least 10 feet of width, 15 feet of driving height and 22 feet of height along the entire unloading path. Section 15-501 of Baltimore City's zoning code limits the combined area of accessory structures to 50% of the required rear yard. That yard is the area across the lot, measured from the rear lot line to the minimum depth set by the zoning district. Call the Office of the Zoning Administrator at 410-396-4126 to ask how the rule applies to your proposed container and location.
Anne Arundel County exempts sheds of 150 square feet or less and no taller than 10 feet from a building permit, except in the Critical Area, the land within 1,000 feet of tidal water, where every shed needs one. A 20ft conex box covers 160 square feet, so call Inspections and Permits at 410-222-7730 with the size and the address.
On a firm, drained spot that stays dry after heavy rain, with blocking or a gravel pad under the four corner castings so the doors keep closing. Land within 1,000 feet of tidal water is in the Critical Area, so ask the county before placing one near a creek or marsh.
It depends on the drive. Describe the grade, the turns and the drop spot in your quote request.
Salt air near the Bay and the ocean rusts bare steel faster, whatever the grade. Touch up scratches and worn paint as they appear, and keep the door gaskets clean so they keep sealing.