A shipping container usually stays in liner service for 10 to 15 years before the shipping line retires it, and it can keep working for 25 years or more as a fixed warehouse, the base of a building or a storage unit, as long as it gets maintenance. The box does not wear out; what runs out is its certification to travel stacked and loaded on a ship.

How long a shipping container lasts

The corten steel it is made of withstands decades. What determines retirement from ocean service is economic and regulatory: when the cost of repairing and recertifying exceeds what it is worth to keep operating it, the shipping line or lessor sells it on the secondary market.

Use	Typical useful life	What limits it
Active ocean service	10 to 15 years	Handling impacts, stacking, salt and recertification cost
Fixed storage or warehousing	25 years or more	Floor and underside corrosion, standing water on the roof, worn seals
Modular construction	Comparable to a light building	Depends on the coating, insulation and maintenance of the envelope

A new or one-trip container arrives without structural fatigue and with its paint intact; a used one has already spent part of that reserve. That is why resale price and remaining life go hand in hand with the number of trips and the quality of the repairs it has received.

How to verify a container's real age

Do not rely on what the seller says: the age is stamped on the equipment itself and can be checked in two places.

The CSC plate

This is the metal plate, normally bolted to the left door, required by the International Convention for Safe Containers (CSC, adopted in 1972 and in force since 1977). It shows:

Month and year of manufacture: the most direct data point for the real age.
Container identification number and the manufacturer's serial number.
Maximum operating gross mass and allowable stacking load.
Transverse racking test value.
Next examination date if the unit is under the periodic scheme, or the ACEP number if it is under an approved continuous examination program.

Under the periodic scheme, the first examination takes place no later than five years after manufacture and the following ones at intervals of no more than 30 months. An illegible or repainted plate, or one with an expired examination date, is a warning sign.

The ISO 6346 identification code

This is the number painted on the doors and sides. Under ISO 6346 it consists of four letters and seven digits:

Three owner letters, registered with the Bureau International des Containers (BIC), that uniquely identify the owner or main operator.
One category letter: U for freight containers, J for detachable equipment and Z for chassis and trailers.
Six serial digits assigned by the owner.
One check digit, calculated from the previous characters, that detects transcription errors.

The owner prefix can be looked up in the BIC public register. That code does not tell you the age, but it does tell you which fleet the unit comes from, so you can cross-check it against the plate. On the paperwork that should come with the purchase, see how to know whether a container is legal.

Commercial grades used by the industry

When buying used, condition is not described with adjectives but with internationally recognized grades. Knowing them avoids misunderstandings:

Grade	What it means	What it is for
One trip	Recently manufactured, used on a single trip from the factory	Export, visible projects, modular construction
IICL-5	Used unit that meets the inspection criteria of the Institute of International Container Lessors	Continued ocean service, long-term leasing
Cargo worthy	Fit for cargo: sound structure, no holes, working doors and valid certification	International shipping
Wind and water tight (WWT)	Sealed against wind and water, no holes or leaks, but not fit to travel	Storage on land
As is	Delivered in its current condition, with visible damage	Scrap, dismantling or projects with major work

The same 12-year-old container can be graded IICL or WWT depending on the maintenance it has received. The grade says more about remaining life than age alone.

Humid, salty climates: the environmental factor

Useful life is decided above all by the environment. In port areas, three things combine to speed up deterioration:

Salt: sea spray attacks welds, hardware and any spot where the paint is scratched.
High, sustained relative humidity: keeps surfaces wet for more hours a day.
Daytime heat and nighttime cooling cycles: cause internal condensation, the so-called container rain, which wets the cargo and rots the wooden floor from above.

The first points to fail are the bottom cross members, when the box sits directly on the ground, and the roof, when it has a slight dip that collects water. Inland, in a drier climate, the same container holds up noticeably better.

Tips to extend its useful life

Set it on supports: concrete sleepers or beams at the four corners so the underside ventilates and does not touch damp ground.
Level it: out of level, the doors go out of alignment and the seals stop sealing.
Washing and cleaning: with a pressure washer, inside and out, with approved products. Removing salt and residue is what extends the paint the most.
Paint and corrosion control: this is not cosmetic. Rust is removed, the coating applied and the process repeated before the corrosion spot perforates the sheet.
Clear drains and roof: no leaves or standing water.
Ventilation and humidity control: unobstructed vents and, for sensitive cargo, desiccant bags.
Door seals: check them and replace them when they lose elasticity; they are the first defense against water.
Tarps and covers: waterproof material on top to protect from sun and rain when the unit sits outdoors for long periods.

Age and resale price

Age weighs on the price, but it is not the only factor and almost never the main one. In practice, resale value moves with the commercial grade and the real condition of the structure and floor; with the validity of the certification (a unit without a valid CSC leaves the export market and competes only as storage); with location, since moving a container costs money and a unit at the port is not worth the same as one inland; and with type and size, because not every format is in equal demand. A well-maintained 15-year-old unit with its papers in order can be worth more than an 8-year-old one punished by corrosion. Conditions change with available supply, so check current availability and condition in our online shop.

Recycling a container

Many containers end their ocean cycle at the ports and start another one on land. They are used as raw material for homes, retail spaces, offices and entire buildings, with a reuse logic that avoids melting down the steel. That second cycle can last decades if the envelope is well cared for, and it is the basis of modular construction.

Frequently asked questions

How old is a typical used container?

The used units that reach the secondary market usually come from fleets retired after 10 to 15 years of service. The exact date is on the CSC plate, and it is always worth checking before closing the purchase.

Is an old container good for building?

Yes, if the structure is sound. For construction, what matters is that the rails and corner posts are intact and the corrosion is superficial; the floor and paint get worked on anyway. For visible projects, a one-trip unit is usually preferred for finish and uniformity.

What happens if the CSC plate has expired?

The container cannot be shipped as a cargo unit until it is examined and recertified. For use on land (warehouse, workshop, job site) it is not disqualified, but its resale value does drop.

How often does a container need painting?

It depends on the environment. In coastal areas the cycles are shorter than inland. The practical reference is not the calendar but inspection: as soon as rust spots break through the paint film, it is time to act.

Is it better to buy new or used?

If the unit is going to travel or be on display in a project, one-trip pays off. For static storage on a tight budget, a WWT in good condition does the job. The decision is made on use, not on age.

New, one-trip and used containers with their grade and location: see what is in stock.