Container grading is not governed by a single standard, so the same unit can be described three different ways by three different yards. This guide explains exactly what we mean by each grade, what you should expect to see, and which grade suits which job.
New / One-Trip
What it is. Manufactured within roughly the last two years and shipped once, usually from the factory in Asia to a North American port with cargo inside. Sold as “new” by most of the industry, because a container is never genuinely sold before its first voyage.
What to expect. Near-flawless paint in the manufacturer’s colour, clean marine plywood floor, tight door gaskets, minimal surface marking. Occasional scuffs and small dents from a single handling cycle.
Best for. Conversions and modifications, customer-facing uses, anywhere appearance matters, and long-term installations where you want maximum service life.
Cargo-Worthy (CWO)
What it is. A used container certified as structurally sound and fit for international shipping. It has passed a survey against CSC criteria.
What to expect. Visible surface rust, dents, scratches and previous owners’ markings. Structurally sound frame, sound floor, functioning doors that seal. Repairs may be present but are properly executed.
Best for. Storage where appearance is secondary, shipping cargo, and conversion projects where you plan to repaint anyway. The best value per cubic metre in most cases.
Wind & Water Tight (WWT)
What it is. A used container that keeps weather out but is no longer certified for international shipping.
What to expect. Heavier corrosion, more significant dents, patched repairs, and faded or mismatched paint. Doors work and seal, roof and walls are sound, floor is dry.
Best for. Static, on-site storage where the container will not be moved again and appearance does not matter. The cheapest way to get secure dry space.
As-Is
What it is. A container sold with known defects, disclosed at the point of sale.
What to expect. Whatever we have described — which might be a hole in the roof, a damaged door, or a soft floor section. Priced accordingly.
Best for. Buyers who intend to cut the container up, use it for parts, or carry out their own repairs.
Modified / Converted
What it is. A container altered from its original form — extra doors, windows, insulation, electrics, HVAC, partitions or a complete fit-out.
What to expect. The listing states the base container’s grade separately from the modification. A one-trip base with a new fit-out is a very different product from a wind-and-water-tight base with the same fit-out, and we price them differently.
Best for. Site offices, welfare units, restroom blocks, workshops, retail and hospitality builds.
Choosing a grade
| Your use | Recommended grade |
|---|---|
| Long-term on-site storage, appearance irrelevant | Wind & Water Tight |
| General storage, may be relocated later | Cargo-Worthy |
| Shipping goods internationally | Cargo-Worthy (CSC plated) |
| Conversion project you will finish yourself | Cargo-Worthy or One-Trip |
| Customer-facing, branded or residential use | One-Trip |
| Occupied year-round in a Quebec winter | One-Trip, insulated and heated |
Standard sizes and capacities
| Size | External (L × W × H) | Internal floor area | Capacity |
|---|---|---|---|
| 10ft | 2.99 × 2.44 × 2.59 m | ~6.5 m² / 70 sq ft | ~15.9 m³ / 560 cu ft |
| 20ft standard | 6.06 × 2.44 × 2.59 m | ~13.6 m² / 146 sq ft | ~33.1 m³ / 1,170 cu ft |
| 20ft high cube | 6.06 × 2.44 × 2.90 m | ~13.6 m² / 146 sq ft | ~37.4 m³ / 1,320 cu ft |
| 40ft standard | 12.19 × 2.44 × 2.59 m | ~27.9 m² / 300 sq ft | ~67.7 m³ / 2,390 cu ft |
| 40ft high cube | 12.19 × 2.44 × 2.90 m | ~27.9 m² / 300 sq ft | ~76.2 m³ / 2,690 cu ft |
Dimensions are nominal. Internal measurements vary slightly by manufacturer — if an exact figure matters to your project, ask us to measure the specific unit.
Things that are not defects
- Surface rust on a used container. Corten steel is designed to form a stable oxide layer. Touch up paint to stop it progressing, and pay particular attention after a winter of road salt exposure.
- Condensation — often called “container rain”. Caused by humidity and temperature swings rather than a leak, and pronounced in this climate where a steel box can go from −20 °C overnight to well above freezing by afternoon. Vents or insulation solve it.
- Previous owners’ markings — shipping line livery and stencilled numbers are normal on used units.
- Mismatched paint where a repair has been made.
- Door stiffness — hinges and locking bars need occasional lubrication, more so after freeze-thaw cycles.
Siting a container for a Quebec winter
The grade you buy matters less than how you set it down. Three things decide whether a container still seals in year five:
- Support all four corners on railway ties, concrete blocks or a prepared pad. A container resting on soil will settle unevenly through a freeze-thaw cycle, and a twisted frame stops the doors closing.
- Keep the roof clear. Container roofs are not designed for heavy accumulated snow load, and standing meltwater accelerates corrosion.
- Allow drainage away from the base so the unit is not sitting in meltwater each spring.
Still unsure?
Contact the yard at info@gtcontainerservices.ca and describe the job. We will tell you which grade you actually need — including when a cheaper one will do.