Buying and Maintaining a Shipping Container: Frequently Asked Questions

Answers to the questions buyers ask most — covering everything from choosing the right size and condition to keeping your container dry, secure, and rust-free for decades to come.

Why buy a shipping container?
What can it be used for?
Choosing the right size
Standard vs. high cube
New vs. used containers
WWT, CW, IICL & AS-IS
Why "letter grades" are a red flag
What drives the price
Getting an accurate quote
Renting vs. buying
How delivery works
Special delivery situations
What makes containers so durable
Site prep & leveling
What causes condensation
Ventilating your container
How many vents, and where
Insulation, desiccants & climate control
Preventing & treating rust
Painting your container
Freeing a stuck door
Fixing a leaking door
Door hardware & gaskets
Keeping your container secure
Shelving & interior organization
Floor care
Cleaning before first use
A seasonal maintenance routine
When to call a professional

Part One · Buying a Shipping Container

Everything to think about before you buy: size, condition, pricing, the buying process, and delivery logistics.

Why buy a shipping container instead of a traditional storage structure?

Shipping containers are built from welded Corten steel and engineered to survive ocean crossings, which is exactly why homeowners, farmers, contractors, and small businesses choose them over traditional sheds or storage structures. That same durability means a container can outlast almost any comparable structure for the same money, with minimal attention.

What can I actually use a shipping container for?

Shipping containers are no longer limited to hauling cargo across the ocean. Today they're used for storage, transportation, and an expanding range of creative projects — everything from backyard sheds and home gyms to art studios, cafés, and pop-up shops.

Explore ideas: Repurposing Shipping Containers

What sizes do shipping containers come in?

Shipping containers are generally available in 20-foot and 40-foot lengths, in standard (8'6") and high cube (9'6") heights. Anything else is a specialty size and will cost more. A 20-foot container offers a secure, durable space for smaller projects or limited storage needs, while a 40-foot container gives you twice the capacity — more room for larger items, seasonal equipment, or retail inventory.

40-foot units do cost more than 20-foot units, but the gap is usually smaller than people expect, so it's worth asking for current pricing on both before you decide.

What's the difference between a standard height and a high cube container?

A high cube container has the same length and width as a standard container but stands a full extra foot taller (9'6" vs. 8'6"). That extra vertical space offers greater flexibility for storing bulky or oversized items, or for interior build-outs like insulation and shelving.

Should I buy a new (one-trip) container or a used one?

A container's condition can have a major impact on its price, appearance, and usable life span. New (one-trip) containers are manufactured overseas, loaded with cargo, and shipped to their destination — having made just a single journey, they're in excellent condition with better curb appeal, undamaged walls and floors, and no logos. They cost more upfront, but the long-term value is often worth it, especially for conversion projects, since a blank slate makes modifications easier and more precise.

Used containers are more budget-friendly and still work well despite dents, faded paint, and patches of surface rust.

What do container conditions like WWT, CW, IICL, and AS-IS actually mean?

Used containers are sold under a handful of standard classifications:

WWT (Wind and Watertight): guaranteed to keep out wind and water — structurally sound, with no holes, intact seals, and functioning doors.
CW (Cargo Worthy): a used WWT container that's been inspected and certified for international shipping. Every cargoworthy container is wind and watertight, but not every wind and watertight container is cargoworthy — unless you're shipping overseas, WWT is all you need.
IICL: containers graded by the Institute of International Container Lessors, used mostly by leasing companies and generally not sold directly to consumers.
AS IS: sold without a warranty. May still be useful for storage or building projects, but only if you're prepared to do some repair work.

Why should I be wary of suppliers who assign "letter grades" (A, B, C) to used containers?

Be cautious of suppliers who use letter grades as a sales tactic. Containers that have been decommissioned and sold as used are no longer formally graded, and prices between reputable suppliers should generally fall within a few hundred dollars of each other when you're comparing apples to apples. A big price gap is usually a sign of a different classification (like an AS-IS unit dressed up as WWT), not a better deal.

What determines the price of a shipping container?

Container pricing depends on several factors: size, type, condition, location, modifications, and delivery costs. 40-foot containers cost more than 20-foot units, new (one-trip) containers cost more than used ones of the same size, and specialty sizes or modified containers (side doors, doors on both ends, insulation, dividing walls) always come at a premium. Delivery prices are based on the distance from the depot to your location — buying from a local seller doesn't automatically mean a lower price, since that seller still pays to have the container transported from the nearest port.

How do I get an accurate quote and avoid getting scammed?

Plan before you purchase — think through how you'll use the container, what size and condition you need, your budget, and whether your site will work. Compare quotes carefully, making sure you're comparing size, type, condition, modifications, and delivery costs apples-to-apples, and check for a wind and watertight warranty unless you're intentionally buying an as-is unit. Look for social proof: verify the seller is reputable and that past customers received containers as represented. If you're buying online and still have concerns, consider a company that offers 100% payment on delivery.

Get a quote: Click, Call, or Chat: Shipping Container Quotes from USA Containers

Should I rent or buy a shipping container?

It depends on how long you need the space and how the numbers work out over time. Renting keeps upfront costs low and makes sense for short-to-medium-term needs, while buying makes more sense if you plan to keep the container for years or want to modify it — since you're building equity in something with resale value instead of paying indefinitely.

How does shipping container delivery actually work?

Getting a container delivered is a lot easier than most first-time buyers expect. The most common method uses gooseneck, tilt-bed (sometimes called roll-off) trailers, which don't require any additional equipment. The trailer tilts back, lowering the edge of the container to the ground, then pulls away, allowing the container to slide off. Before delivery, you'll let the driver know which way you want the doors facing, and they'll take care of positioning it from there.

What if my site has unusual delivery constraints?

Many suppliers can accommodate special situations — like delivering two 20-foot containers on the same trailer, or a 20-foot unit on a shorter trailer — with advance notice. If your site has tight access, low overhead clearance, or a steep driveway, ask about special arrangements before your order is finalized, not after the truck is en route.

Also see: Materials to Use When Placing a Shipping Container on Your Property

Part Two · Maintaining Your Shipping Container

Everything that keeps a container in good shape after it's delivered — from ventilation and rust prevention to door care, leveling, security, and the small habits that make the difference in how long your container lasts.

What makes shipping containers so durable?

Shipping containers are made from Corten steel, also known as weathering steel — a durable material engineered to handle harsh marine conditions and prolonged exposure to salt water. When exposed to the elements, Corten steel develops a protective surface layer that slows corrosion, allowing containers to stay wind and watertight for years of outdoor use. That steel, combined with a load-bearing structure of cross members, corner posts and castings, and marine-grade plywood flooring, is what makes containers so strong.

Do I need to prepare or level the ground before placing a container?

Yes. A container that isn't level can create problems over time, including doors that become difficult to open or don't seal properly, and ongoing stress on the frame. Shipping containers are engineered to be supported at the corner castings, so set the container on solid footings at the corners, or use railroad ties to distribute weight evenly. Avoid supporting only the middle (it stresses the floor and frame), unstable stacked blocks or rotting wood, and skipping ground prep on soft or uneven ground.

How do I check and fix a container that's out of level?

Use a long level on the floor and the bottom of the door frame, checking all four corners — what matters most is that the corners sit level relative to each other. Lift one corner at a time with a jack rated for the container's weight (a 12-ton bottle jack and leveler booster bracket handles most jobs), add stable support beneath it, and recheck with your level until all four corners are even.

What causes condensation ("container rain") inside a shipping container?

Condensation forms when warm, moisture-laden air meets a surface colder than the air's dew point — in a shipping container, that surface is the steel. The sun heats the steel and interior air during the day, and the container cools quickly after sundown; as the air cools, it releases moisture that collects on the ceiling and walls if the container isn't properly ventilated. Three things feed the problem: temperature swings between day and night, trapped humidity from damp goods or wet pallets, and no airflow to let humid air escape.

How do I ventilate a shipping container?

Ventilation is the single most important upgrade for a shipping container — a sealed steel box traps heat and humidity, and proper airflow is one of the simplest, most cost-effective ways to prevent rust and moisture damage. The most important rule: for air to actually move, you need an intake and an exhaust. Mount a vent low on one end (intake) and a vent high on the opposite end (exhaust) so air moves through the entire length of the container.

There are three types of ventilation: passive vents (louvered openings, no moving parts, most affordable), powered vents (an electric fan that actively exhausts air, best for workshops or humid climates), and solar-powered vents (active ventilation with no wiring or electricity costs, ideal for most owners).

How many vents do I need, and where should they go?

A 20-foot container is usually fine with one or two vents; a 40-foot typically needs at least two for proper cross-flow. Installing a vent is a manageable DIY project — most come with a cut-out template and instructions: cut the opening with a jigsaw or angle grinder, seat the vent, fasten it, and seal the edges. Most installs take under an hour per vent with basic tools.

Do I need insulation, desiccants, or active climate control?

For most storage containers, you don't need every option on the list. Start with proper cross-ventilation and add desiccants (which pull humidity directly from the air) if you're storing anything moisture-sensitive — that combination tackles the root cause for a fraction of the cost of full insulation or active climate control.

Insulation (spray foam or rigid panels) keeps interior steel closer to air temperature so it's less likely to drop below the dew point, and is worth the extra effort for climate-controlled uses like tiny homes, offices, or workshops. Active climate control — a small dehumidifier or thermostatically controlled heater — is the most expensive, energy-dependent option, best reserved for high-value or highly sensitive contents in harsh climates.

How do I prevent and treat rust on a shipping container?

Over time, every shipping container develops some surface rust; ignored, it eventually creates holes in the steel. Regular inspection and proactive maintenance is the cheapest, most effective way to prevent it. To treat a spot: clean the area with vinegar or a commercial rust remover and let it dry completely, then remove the rust with a wire brush (finishing with sandpaper — avoid abrasive sandblasting on small spots, since it strips more of the original protective coating than necessary). Apply a rust converter, let it dry fully, then paint over the treated area with marine-grade, direct-to-metal (DTM) paint. If corrosion has penetrated deep into the steel or caused structural issues like warping or weakened joints, consult a professional.

Do I need to paint my container, and what kind of paint should I use?

You don't have to paint your container — it already has a protective coating designed to last for years. But a new coat can add curb appeal and an extra layer of protection. The best choice is a marine-grade, direct-to-metal (DTM) paint; no primer is needed since it bonds directly to bare steel, and it adds useful thermal and soundproofing properties as a bonus. It's widely available from brands like Valspar, Rust-Oleum, and Sherwin-Williams. Before painting, power wash the container and let it dry thoroughly, remove stickers, and spot-treat small rust spots with a wire brush (power washing plus targeted rust treatment beats full sandblasting, which can strip the factory coating). Use a thick-nap roller for large flat areas, a brush for corners and seams, or a sprayer for a smoother finish — DTM paint has little to no VOCs, so it's safe even in a relatively enclosed space.

As a rough guide, a 20-foot container (standard or high cube) needs about 3–4 gallons; a 40-foot needs about 5–6 gallons.

How do I free a door that's stuck or hard to open?

Container doors can become stiff over time from rust on the locking bars, dry cam mechanisms, or a container that has settled out of level. Don't force a stuck door — you could bend the hardware or injure yourself. A leverage bar gives you the extra mechanical advantage needed to free stiff locking bars safely, and lubricating the cams, hinges, and keepers helps too. Also check that the container is sitting level; if one corner has shifted, the frame can twist and cause doors to bind.

How do I fix a leaking door?

If water is getting in around the doors, the rubber gasket is usually the problem. Over years of sun, weather, and everyday use, gaskets can harden, crack, or compress, which prevents them from sealing properly — once the seal fails, water can run in along the edges and create the moisture conditions where rust develops. Replacing the gasket restores the weatherproof seal and keeps out water, dust, and drafts. Also confirm the doors close fully and the locking bars seat properly — a door that doesn't shut squarely will leak even with a brand-new gasket.

How do I maintain door hardware and gaskets over time?

The locking system — vertical bars, handles, cams, and keepers — wears down over time. If a handle is loose, a cam no longer catches, or a keeper is bent, the door may not close securely. Rather than replace the whole door, you can usually just replace those individual parts. Build a routine of checking door gaskets for cracking or gaps, lubricating hinges, cams, and locking bars, and confirming doors close fully and squarely.

How can I keep my shipping container secure?

Containers are a secure storage option on their own, but many owners add upgraded locking hardware for extra peace of mind, especially for tools or valuable equipment. Options include a bolt-on lock box (covers the locking mechanism and padlock entirely, so there's no exposed shackle to target), a heavy-duty closed-shackle padlock (far stronger than a basic exposed-shackle lock), and a heavy-duty door bar lock system that adds a second, independent layer of security around the existing locking bars. Beyond hardware, installing CCTV cameras and lighting are effective deterrents — visible monitoring and well-lit storage areas discourage attempts before they start.

What shelving and storage options work best inside a container?

A shipping container gives you a large, secure, weatherproof space, but making the best use of it means using vertical space, not just the floor. Options include D-ring bracket shelving (hangs from the lashing rings welded into the top of the container — no drilling, fully removable and reusable, works even in rented containers), pipe rack shelving (shaped for long materials like lumber and conduit), freestanding units (quick to set up and movable but use floor space), and hanging storage like rails, hooks, and magnets — since container walls are steel, magnetic organizers stick anywhere with no mounting at all.

How do I take care of the floor?

The floor works just as hard as the doors, roof, walls, and locking hardware — it's made from marine-grade plywood and can wear down under foot traffic, forklifts, or heavy equipment. Keep goods off the floor on pallets or shelving so air can circulate underneath and water can't wick upward, avoid loading damp items or wet pallets, and don't pack the container too tightly. Clean regularly with a mild detergent and soft-bristled brush, consider caulking the floor seams to keep out bugs, and watch for staining, soft spots, or delamination — signs that the container needs better ventilation or has a leak.

How should I clean my container before first use?

Before loading anything in, it's worth giving a used container a thorough cleaning: power wash the interior and exterior, remove any leftover stickers or residue, and spot-treat surface rust. This also gives you a chance to spot problems early — check the floor for stains or soft spots, inspect door gaskets, and confirm vents are clear before you start storing anything inside.

What's a good seasonal maintenance routine?

Maintenance doesn't need to be complicated — most owners who get decades of trouble-free use are doing a few simple things consistently:

Every season, at minimum twice a year: walk the full exterior and check for new dents, rust, or chipped paint (treat rust right away); check door gaskets for cracking or gaps and confirm doors close fully and squarely; clear the roof and surrounding area of leaves, debris, and standing water; confirm vents are unobstructed; check the floor for stains or soft spots; lubricate hinges, cams, and locking bars.
Once a year: do a thorough check for rust spots, including the undersides of visible seams and door hardware, and touch up any chipped or peeling paint.
After any storm or major weather event: inspect the roof and walls, check for water intrusion around doors, vents, and modifications, and confirm the container hasn't shifted or settled out of level.

If you only do one thing consistently, make it this: walk around and through your container a few times a year and actually look. Most of the expensive problems — deep rust, structural rot, failed door hardware — start as small, cheap-to-fix issues that simply went unnoticed for too long.

When should I call a professional instead of doing a DIY repair?

Most container maintenance — rust spot treatment, painting, vent installation, gasket replacement, hardware swaps — is a manageable DIY project with basic tools. But if corrosion has penetrated deep into the steel or caused structural issues like warping, holes, or weakened joints, consult a professional. Welding patches, replacing corroded structural components, or reinforcing weakened areas requires specialized tools and training beyond a typical DIY repair.

Ready to find your container?

Click here for an automated shipping container quote from USA Containers or call 877-395-6851 to speak with one of our knowledgeable sales agents.