Open Top & Side Door Shipping Containers: Full Specs Guide

Open Top and Side Door Containers: The Direct Answer

Open top containers and side door containers are specialized ISO intermodal units designed for cargo that cannot be loaded through standard end doors — either because it is too tall, too heavy for forklift access, or requires crane loading from above or side-access forklift loading along the full container length. The 20-foot open top container is the most widely available variant, offering a removable tarpaulin roof and a removable or bowing header bar at the door end to allow crane or overhead loading of oversized cargo. The 20-foot side door container adds one or more full-length doors along the container's long face, enabling side-loading with reach trucks or forklifts without the depth limitation of end-door-only access.

Both container types are available through major ocean carriers and container leasing companies, though they represent a smaller proportion of the global fleet than standard dry containers. Understanding their exact specifications, freight surcharges, and loading constraints is essential before booking either type.

20-Foot Open Top Shipping Container: Dimensions and Specifications

The 20-foot open top container (ISO type code OT20) is built to the same external footprint as a standard 20-foot general purpose container but replaces the fixed steel roof with a removable tarpaulin cover supported by removable or swing-aside roof bows. The door end header bar can also be removed or bowed outward to allow cargo taller than the internal height to protrude above the container frame during loading before the tarp is fitted.

Note that the open top container's internal height is slightly less than the standard dry container — the roof bows and the tarpaulin fixing rail reduce available headroom by approximately 40 mm. However, the key advantage is that cargo can protrude above the container frame height when the tarpaulin is lashed over protruding cargo. Carriers typically permit over-height protrusion up to 300 mm above the top rail without special approval; greater protrusion requires out-of-gauge (OOG) booking and may necessitate on-deck stowage only.

40-Foot Open Top Container

The 40-foot open top container (OT40) is also widely available and follows the same construction principle. Its internal length of approximately 12,020 mm makes it suitable for longer cargo items such as structural steel sections, yacht masts, wind turbine blades (shorter sections), timber packs, and machinery frames. Payload capacity is approximately 26,500 kg with a tare weight of around 3,900 kg and a cubic capacity of approximately 65.5 m³.

How Open Top Containers Are Loaded: Crane and Overhead Loading in Practice

The defining operational advantage of an open top container is the ability to load cargo from directly above using a crane, overhead bridge, or gantry — eliminating the need to maneuver heavy or awkward items through the end door aperture. This is critical for commodities that are dense, fragile in horizontal handling, or simply too tall to pass through the standard door height of 2,280 mm.

Loading Procedure

1. Remove or swing aside the roof bows. On most modern open top containers, the bows slide out of their sockets in the top rails and are stored separately or in a designated holder on the container frame.
2. If loading tall cargo through the door end, remove the detachable header bar (the horizontal beam across the top of the door frame). This beam must be reinstalled after loading and before transport.
3. Lower cargo into the container using the crane, ensuring the load is positioned and secured before the hook is released. Timber dunnage, blocking, and bracing should be pre-positioned.
4. Lash and secure the cargo to the container's lashing rings (typically rated at 1,000–2,000 kg per ring, located on the floor and lower corner posts).
5. Reinstall roof bows and fit the tarpaulin cover. The tarpaulin must be secured with cross-lashing over the top and tied to the bottom side rails. A standard open top tarpaulin is heavy-duty PVC-coated polyester, waterproof to at least IPX6 equivalent when correctly installed.
6. Reinstall the header bar if it was removed. Apply a shipper's seal to the doors.

For cargo that protrudes above the container top rail — a valid and common use of the open top format — the tarpaulin is lashed directly over the protruding cargo. The carrier must be notified of the protrusion height at booking, and the bill of lading will note the cargo as out-of-gauge. On-deck stowage is mandatory for protruding cargo as it cannot be safely stacked under other containers.

Typical Cargo Loaded in Open Top Containers

• Granite and marble slabs: Stone slabs are typically craned in on A-frame stands or flat-packed in bundles. The weight density of stone (2,600–2,900 kg/m³) means a 20 ft open top can be volume-filled with stone while remaining within payload — unlike a standard dry container where weight often limits fill before volume is reached.
• Steel coils and structural sections: Hot-rolled steel coils weighing 15–25 tonnes each are craned into open top containers on timber cradles. Structural sections (I-beams, columns) too long for a 20 ft but suitable for a 40 ft open top are a staple cargo type.
• Industrial machinery and equipment: Press machines, compressors, generators, and other plant equipment that exceeds standard door height or is impractical to rig through an end door.
• Timber packs and lumber: Long timber packs craned in from above, particularly when the timber length matches or approaches the container's internal length.
• Vehicles and agricultural equipment: Tractors, combines, and construction equipment that cannot be driven in through the end door due to height can be lowered in through the top opening.
• Bulk bagged commodities: When a crane with a grab or bulk bag crane attachment is available, bulk materials in flexible intermediate bulk containers (FIBCs) are loaded from above for efficiency.

20-Foot Side Door Shipping Container: Specifications and Access Advantages

A side door (or side opening) container — sometimes called a "full side access container" or "side loader container" — adds one or more full-length door panels along one or both of the container's long sides, in addition to or instead of the standard end doors. The 20-foot side door container provides access to the entire 5.9-metre length of the container from the side, eliminating the reach limitation of end-door-only loading where forklift operators must maneuver pallets to the far end of the container through a 2.34-metre wide aperture.

Construction and Door Configuration

Side door containers are typically constructed on a standard ISO 20-foot or 40-foot frame, with the side wall replaced by two to four hinged steel door panels that swing outward to provide a full or near-full opening along the container length. The doors are secured by cam-action locking rods identical to those used on end doors, and the same gasket sealing system makes the container weathertight when closed.

Key dimensional facts for a 20-foot side door container:

• Side door opening length: approximately 5,500–5,700 mm — nearly the full internal length of the container.
• Side door opening height: approximately 2,200–2,280 mm — full internal height less the door frame sill and header.
• External dimensions: Identical to a standard 20-foot ISO container (6,058 × 2,438 × 2,591 mm) — fully intermodal compatible for shipping and stacking.
• Payload: Slightly reduced vs. standard dry — approximately 25,000–27,000 kg due to the additional weight of the door panels and reinforced frame members replacing the standard side wall corrugations.
• Structural integrity: The side walls of a standard container contribute to its racking strength. Side door containers compensate with reinforced corner posts, additional cross-members, and heavier floor structure — essential to maintain the ISO stacking certification (up to 192,000 kg stacking load for 9-high stacking at sea).

Side Opening Container Applications: Where They Solve Real Problems

Side door containers were developed to address specific loading and unloading inefficiencies that end-door-only containers create in certain logistics environments. Their adoption has accelerated in distribution, retail supply chains, and any application where loading speed and access flexibility matter more than minimizing equipment cost.

Palletized Retail and FMCG Distribution

Loading a standard 20-foot container with 11 pallets (the typical maximum for a 20 ft end-door container using standard 1,200×1,000 mm pallets) requires each pallet to be driven approximately 5 metres into the container with the first pallet. With a side door container, all pallets can be placed simultaneously from the side — a process that reduces stuffing time from 45–60 minutes to 10–15 minutes in well-organized distribution operations. This time saving is significant when handling high volumes of containerized retail freight.

Long Cargo and Awkward Items

Items that fit within the container's height and width envelope but are too long or too stiff to maneuver through an end door are natural candidates for side door containers. Examples include:

• Bundled steel reinforcing bar (rebar) in lengths of 5–6 m
• Pre-assembled pipe sections, handrails, or structural steel frames
• Furniture and interior fitout components for hotels and commercial projects
• Rolled carpets, rolls of fabric, and flooring materials
• Automotive parts on purpose-built side-loading racks

Storage and Portable Site Facilities

Side door containers are extensively used as on-site storage units and portable buildings where side access is operationally superior to end-door-only access. A construction site store container with a full-length side door allows workers to see and access any item in the container without shuffling stock forward from the back — reducing retrieval time and improving inventory control. Portable workshops, tool stores, and parts containers on mining and oil and gas sites increasingly specify side door or combination end-plus-side-door configurations.

Freight and Commercial Considerations for Booking Open Top or Side Door Containers

Booking a specialty container involves considerations beyond simply specifying the equipment type. Shippers unfamiliar with OOG (out of gauge) and specialty equipment freight often encounter unexpected costs or delays.

Equipment Availability and Booking Lead Time

Open top containers represent approximately 2–3% of the global container fleet of roughly 50 million TEU. Side door containers are even rarer — under 1% of fleet — and are predominantly owned by leasing companies and specialist logistics operators rather than major ocean carriers. Equipment availability varies significantly by port and trade lane. On high-volume trade lanes (Asia–Europe, Transpacific), open tops are generally available with 5–10 business days' notice; on secondary routes or at smaller ports, lead times of 2–4 weeks are common. Always confirm equipment availability with your freight forwarder before fixing cargo booking dates.

Surcharges and OOG Freight Rates

Specialty containers attract freight premiums over standard dry containers on the same trade lane:

• Equipment surcharge: A fixed additional charge per container for using specialty equipment, typically USD 150–400 per container depending on carrier and trade.
• OOG surcharge (open top with protruding cargo): When cargo protrudes above the container top rail, the container must be stowed on deck and occupies exclusive deck space. OOG surcharges are typically calculated based on the protrusion dimensions — USD 200–600 per container for minor overage; significantly higher for major OOG dimensions that displace adjacent deck slots.
• Tarpaulin charges: Some carriers charge separately for tarpaulin supply and replacement if the tarp is damaged during loading or transit — typically USD 100–300 per tarpaulin. Shippers should confirm whether the tarpaulin is included in the equipment hire or charged separately.
• Port handling surcharges: OOG cargo typically requires manual positioning and securing at the terminal rather than automated crane handling, attracting additional terminal handling charges (THC) at both origin and destination ports.

Documentation Requirements for OOG Shipments

For open top containers carrying cargo that protrudes above the top rail, the shipping instruction must include precise measurements of the cargo overage in all dimensions. The carrier's operations team uses this data to plan deck stowage and confirm that the protrusion does not conflict with adjacent containers, cranes, or hatch covers. Required information typically includes: over-height measurement (mm above top rail), over-width measurement (mm beyond each side rail if applicable), over-length measurement (mm beyond end frames if applicable), and the weight distribution on each container floor quadrant. Inaccurate or incomplete OOG declarations are a significant cause of cargo rejection at the terminal gate.

Securing Cargo in Open Top and Side Door Containers: Safety and Compliance

Cargo securing in specialty containers must meet the requirements of the IMO/ILO/UNECE Code of Practice for Packing of Cargo Transport Units (CTU Code) and the carrier's specific cargo securing manual. Poorly secured cargo in an open top container is a disproportionate risk because the absence of a fixed roof means there is no upper structural restraint — cargo can shift vertically as well as horizontally under ship motion.

Key cargo securing requirements for open top containers:

• Floor lashing rings: Standard open top containers have lashing rings on the floor and lower corner posts rated at 1,000–2,000 kg per ring. The securing plan must use sufficient rings to restrain the cargo against the design accelerations specified in the CTU Code — typically 0.8g longitudinal, 0.5g transverse, and 0.5g vertical for deep-sea voyages.
• Timber dunnage and blocking: Heavy cargo such as steel coils or machinery must be set on timber dunnage (typically 75–100 mm thick hardwood) to distribute point loads across the container floor. Floor point load limits for standard ISO containers are 5,400 kg per forklift axle load and a maximum of 2,700 kg/m² distributed load — limits that stone slab and machinery cargoes regularly approach.
• Wire rope lashings and chain binders: For heavy machinery and steel cargo, wire rope slings or chain lashings with tensioning devices (ratchet binders or bottle screws) are required in addition to webbing straps. Webbing straps alone are generally insufficient for cargo exceeding 5,000 kg per securing point.
• Void filling: Any void space between the cargo and the container walls must be filled with dunnage bags, timber blocking, or foam inserts to prevent cargo movement during voyage. A 100 mm gap between a 20-tonne steel coil and the container end wall is sufficient to allow catastrophic cargo shift in heavy weather.

For side door containers, the additional consideration is that the side door panels — while structurally equivalent to the end doors — are not designed to resist lateral cargo pressure. Cargo must never be loaded in direct contact with the side door panels. A minimum clearance of 50–100 mm between cargo and the closed side door panel should be maintained, with blocking to prevent the cargo from shifting into contact with the doors during transit.