Shipping Container Inspection Checklist Ontario: 10 Points Before You Buy

By Christian LeBlanc, second-generation operator, and Paul LeBlanc, owner, Van Blanc Ent. Inc.

Reading time: about 14 minutes.

Why should you inspect a shipping container before you buy it?

A pre-purchase shipping container inspection is a 15 to 30 minute walk-through that checks ten structural and weather-integrity points before money changes hands: CSC plate, exterior walls, roof, floor, cargo doors, corner castings, undercarriage, interior, welds, and grade verification. Buyers who inspect in person at the yard catch roughly 95 percent of the issues that a paid surveyor would find.

A shipping container is a 4,000 to 8,000 kg steel structure that will sit on your property for 20 to 30 years. The difference between a sound container and a problem container shows up in the first month of ownership: water leaks, door seal failures, floor delamination, hidden rust. Buyers who walk the container at the yard catch most of these issues in 15-30 minutes of inspection. Buyers who skip the inspection step, especially remote Facebook Marketplace purchases, discover the issues after delivery when remediation is far more expensive.

The good news is that container inspection is straightforward. There are no specialized tools required for the basics, no engineering qualifications needed, and the 10-point framework below catches the issues that matter. Walk the container with this guide in hand and you will spot 95 percent of what an industry surveyor would find.

What does a 10-point shipping container inspection cover?

A 10-point shipping container inspection covers the CSC plate, exterior walls, roof, floor, cargo doors, corner castings, undercarriage, interior walls, weld integrity, and grade verification. Industry convention is a 7-point or 8-point checklist that surveyors use for IICL-grade certification. The Van Blanc framework extends this to 10 points specifically for Ontario buyers shopping used containers. Walk the container in this order and you will not miss anything important.

1. CSC plate (verify legitimacy and read manufacturer + age)
2. Exterior walls and corrugation (rust, dents, holes)
3. Roof (pinholes, pooling, dents, prior patches)
4. Floor (plywood condition, water damage, pesticide treatment)
5. Cargo doors (operation, seals, cam locks)
6. Corner castings (4 corners, top and bottom = 8 total)
7. Undercarriage and cross-members (rust, bending, prior damage)
8. Interior walls (light penetration, corrosion, prior modifications)
9. Weld integrity (factory welds and any prior repair welds)
10. Grade verification (does the asking grade match observed condition)

Total inspection time: 15-30 minutes per container for an experienced buyer, 30-60 minutes for a first-time buyer learning the framework. If you are still deciding which grade fits your use, our broader walkthrough of choosing a second-hand unit goes deeper on that decision.

Point 1: How do you read a CSC plate on a shipping container?

The CSC (Consolidated Safety of Containers) plate is a metal tag on the cargo door frame listing manufacturer, build date, owner number, gross weight rating, and timber treatment chemistry. Every legitimate shipping container has one. Containers without a CSC plate are either ex-export units stripped for domestic use or, occasionally, fakes.

What to verify on the CSC plate:

• Manufacturer name. Look for known builders: CIMC, Hyundai, Singamas, Maersk Container Industry, CXIC, Pacific Container Manufacturing. Off-brand names without internet presence are red flags.
• Build date. Format varies: “MFGR” date or “Date of Manufacture”. A 2008-build container in 2026 is 18 years old; expect more wear. A 2022-build is essentially new.
• Container number. 4 letters + 7 digits (e.g., MAEU 1234567). Verify this matches the markings stenciled on the exterior. Mismatch suggests the plate was swapped from another container.
• Gross weight (MGW or Max Gross). Typically 30,480 kg for standard ISO containers. Lower numbers suggest specialized or older builds.
• Timber component treatment. Modern: BASILEUM SI-84, TAELILIUM 400, RADALEUM. Older (pre-2000): CCA arsenic. We cover what that older treatment means for buyers in our piece on replacing a container plywood floor.

Point 2: Exterior walls and corrugation

Walk all four sides of the container. Look for:

• Surface patina (orange-brown). Normal for any used container 3+ years old. Not a defect.
• Active pitting (small dark spots with depth). Concerning if widespread. Acceptable in isolated patches that have been treated.
• Through-rust (visible holes). Serious defect. Either repaired (welded patch visible) or rejected for purchase.
• Dents. Surface dents under 1.5 inches deep typically acceptable per IICL standards. Deeper dents (over 2.5 inches) suggest impact damage and may indicate frame distortion.
• Paint condition. Faded factory paint is normal. Heavy peeling or evidence of recent overpaint may be hiding rust or damage.
• Prior repair patches. Welded patches over former damage areas are acceptable if the weld is sound and the patch is primed and painted. Numerous patches suggest a hard-life container.

Point 3: How do you inspect a shipping container roof?

A shipping container roof is inspected from above, not from the ground. Climb onto the container roof with a ladder (typical roof height: 8 ft 6 in standard, 9 ft 6 in high cube). Walk the entire roof. Look for:

• Pooling spots (low areas). Slightly concave areas where water collects after rain. Acceptable in isolated 6-inch diameter patches; concerning if widespread.
• Pinholes. Small dark spots where rust has eaten through. Hold a flashlight from inside the container to confirm. Pinholes are repairable, but the cost climbs with the number of patches needed and whether the work is contracted out.
• Prior roof patches. Welded steel patches or applied roof coating layers. Acceptable if professional; concerning if poorly done.
• Dents from impact. Forklift damage from container stacking. Cosmetic only unless the dent has cracked the roof seam.
• Roof corrugation integrity. The roof has shallow corrugation channels that drain water sideways. If channels are crushed or filled with debris, drainage fails and pinholes follow.

The roof is the #1 lifespan-limiting area for Ontario containers. Skipping this inspection is the most expensive mistake buyers make.

Point 4: How do you check a container floor for damage?

A container floor is checked by walking its full length and width inside the unit, feeling for flex and looking for water staining. Look for:

• Soft spots or springiness. Indicates moisture damage or rot. Walk in deliberate, heavy steps. Solid floor will not flex more than 5-10 mm under your weight.
• Visible water staining or warping. Especially at floor edges where they meet the side walls. Long-term water exposure shows here first.
• Pesticide treatment marking. Check the CSC plate (point 1). Floor may be marked with a treatment stamp or label.
• Prior patches or replacements. Replaced floor panels are acceptable if professionally installed (proper fasteners, sealed seams). Bad patches suggest other deferred maintenance.
• Floor bolts. Should be present every 12 inches in a grid pattern. Missing bolts indicate prior removal of the original floor.
• Stains and contamination. Oil, chemical, or unknown liquid stains. May affect future use (especially for food-grade or residential conversion).

Point 5: How do you test cargo doors and seals?

Cargo doors and seals are tested by opening and closing both doors and checking that they swing, lock, and seal cleanly. Verify:

• Doors open and close smoothly. Heavy doors that bind, scrape, or require force suggest frame damage or hinge wear.
• Cam locks engage cleanly. Both upper and lower cam handles should rotate fully and lock with audible engagement.
• Door seals compress. Squeeze the rubber gasket between the door edge and the door frame. Should compress 3-5 mm under finger pressure. Rigid, brittle seals fail in service.
• No light penetration with doors closed. Have a partner stand inside while you close the doors from outside. Walk the inside perimeter looking for daylight. Light penetration means seal failure.
• Hinge pins and gear secure. Cam handles, locking bars, and hinges should not have visible wear or play.

Point 6: What should corner castings and the frame look like?

The 8 corner castings (4 corners x 2 each, top and bottom) are the load-bearing connections of the container, and on a sound unit they are crack-free, square, and undamaged. Inspect each:

• No visible cracks or deformation. Heavy welds connect castings to side rails. Cracks indicate prior structural impact.
• ISO 1161 hole pattern intact. The casting hole pattern is the connection for twist locks and lifting gear. Damaged holes prevent stacking.
• No prior repair welds on castings. Repaired castings should be approached with caution; the structural integrity may be compromised.
• Square and plumb. Use a level to verify the castings are not pushed out of position. A pushed corner suggests the container has been dropped or impacted hard.

Point 7: How do you inspect the undercarriage and cross-members?

The undercarriage and cross-members are inspected by looking under the container from one end. The cross-members are the steel ribs every 12 inches that support the floor. Look for:

• Surface rust on cross-members. Normal in 10+ year old containers.
• Pitting or thinning steel. Concerning if widespread. Check thickness with a calliper if available.
• Bending or distortion. Cross-members should be uniformly straight. Bent cross-members indicate prior overload damage.
• Bottom rail integrity. The two long steel rails on each side are load-bearing. Cracks or repairs are serious.
• Prior welded patches or reinforcement. Acceptable if professional; concerning if rough.

Point 8: How do you check interior walls for corrosion and leaks?

Interior walls are checked from inside the container with the doors closed and a flashlight, watching for daylight and surface rust. Inside the container with doors closed and a flashlight:

• Walk the perimeter. Look for daylight through wall corrugation seams or corner welds. Light means leaks.
• Inspect for interior corrosion. Especially in corners and along the floor-to-wall transition. Surface rust here is the leading edge of long-term deterioration.
• Look for prior modifications. Cut openings, welded patches, removed doors. These need to be assessed for structural and weather integrity.
• Check ceiling for condensation staining. Dark streaks running down from the ceiling indicate the container has experienced significant condensation cycles, which our notes on stopping container sweat in an Ontario winter explain how to prevent.
• Smell test. Containers used to ship hazardous materials, agricultural chemicals, or strong-smelling cargo can carry residual odors that persist for years. Reject if odor is strong.

Point 9: How do you judge weld integrity on a used container?

Weld integrity is judged by comparing factory welds against any repair welds, looking for uniform beads and full penetration. Original factory welds are typically excellent. Repair welds vary widely. What to look for:

• Continuous, uniform weld beads on factory welds. No skips, no porosity, no cold lap. The container left the factory as a structural unit.
• Repair welds: penetration and uniformity. A good repair weld has full penetration through the steel and a uniform bead. A bad weld has obvious skips, undercut, or appears to just sit on top of the steel.
• Cracked or compromised welds. Major safety issue. Reject the container or require repair before purchase.
• Welds at modifications. Cut openings, door retrofits, vent installations. The weld integrity here determines whether the modification will hold.

Point 10: How do you verify a container matches its claimed grade?

You verify a container grade by matching the seller’s claimed grade against what your inspection actually finds. The seller claims a grade. Your inspection verifies it. Standard grades and what each should look like in person:

If the inspection reveals condition meaningfully below the claimed grade, negotiate price down or walk away. A WWT container priced as CW means you are paying a Cargo Worthy premium for a Wind and Water Tight unit. When you would rather skip the guesswork, every unit in our Brantford stock you can come and walk yourself is graded by a person before it is offered.

What are the red flags that mean you should walk away?

The clearest walk-away red flags on a used shipping container are a missing or mismatched CSC plate, a seller who refuses on-site inspection, floor delamination, multiple unrepaired roof pinholes, and a price that sits far below every legitimate Ontario quote.

• No CSC plate or plate doesn’t match exterior markings. Possible stolen container.
• Seller refuses on-site inspection. No legitimate Ontario seller blocks this. Photo-only sales are a major scam indicator.
• Floor has visible delamination or soft spots. Major remediation cost.
• Roof has multiple unrepaired pinholes. Imminent water leak issues; substantial repair required.
• Doors will not open or close cleanly. Frame may be racked from impact damage.
• Cracked or repaired corner castings. Structural integrity compromised; stacking capability lost.
• Strong odors that persist. Hazardous materials residue cannot always be cleaned out.
• Price meaningfully below market. If a 20ft Cargo Worthy container is offered far below what every legitimate Ontario yard is quoting, something is wrong. The bin that looks suspiciously cheap on Facebook is usually the bin that never arrives, and we break down how those marketplace cons typically unfold in a dedicated read.
• Seller pressure to commit quickly without inspection. Legitimate sellers want educated buyers; pressure sellers are protecting something.
• Seller cannot answer technical questions about the container. Real dealers know their inventory; flippers and scammers do not.

Paul on what 30 years of yard inspections has taught us

Van Blanc has inspected thousands of containers across three decades of Ontario buying, selling, and trading. The patterns are consistent.

Christian, his son, adds the modern context: “We see more remote-purchase scam victims now than we did ten years ago. The pattern is always the same: too-good-to-be-true price, Facebook Marketplace listing, photos that look professional, seller pressure to commit. The buyers who visit our yard and inspect in person never end up in that situation. The yard visit is the difference between an asset and a loss.”

Frequently asked questions

Reach Van Blanc in Brantford

We have been supplying shipping containers across Ontario since 1995. Our warehouse is at 90 Morton Avenue East in Brantford, and we deliver across Ontario in 1 to 3 days from our four Brantford yards. No surprise fees, no chase-the-paperwork. Every quote comes with a real lead time, not a hopeful one.

Van Blanc Ent. Inc. 90 Morton Ave E Unit 1B, Brantford, ON N3R 7J7. +1 888-509-6658

Walk our yard before you commit. We have 200 plus containers in stock across every grade from one-trip to as-is. You walk the bin with Paul or Christian, you read the CSC plate, you climb the roof if you want. With every grade in stock you pick the right unit for your inspection comfort and budget. Most Ontario container suppliers do not let you choose. We do.

Related Reading

• a closer look at used container buying
• Shipping Container Lifespan Ontario
• more on new and used container comparison
• Shipping Container Scams: How to Spot and Avoid
• Container Condensation Ontario
• Container Flooring Replacement Ontario