Container Cleaning Ontario: Decontamination, Floor Prep, and Food-Grade Conversion

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

Reading time: about 13 minutes.

What does container cleaning in Ontario actually involve?

When most Ontario buyers say cleaning, they picture a hose, a broom, and an afternoon. The reality is broader. A used 20 foot or 40 foot shipping container has spent eight to twelve years moving cargo across oceans, sitting in port yards, and ferrying goods inland. It has carried coffee beans, vehicle parts, agricultural inputs, electronics packed in petroleum-treated cardboard, and on the rougher end, fertilizers and industrial chemicals. The interior surfaces hold every chapter of that history.

Cleaning a shipping container is the work of removing what you can see and neutralizing what you cannot. That breaks into four jobs: pressure washing the steel walls and ceiling, degreasing oil and adhesive marks, addressing the pesticide-treated plywood floor, and dealing with any cargo-specific residue or odour. For workshop and storage uses, the first three are enough. For habitable conversions, paint booths, or anything food-adjacent, the floor question gets larger. If you are weighing a longer-term care plan, the broader care-and-upkeep playbook for Ontario owners sets cleaning in the full lifespan picture.

Across Ontario the cleaning brief also shifts with climate. Boxes coming into our four Brantford yards in late autumn carry sea salt residue that flashes new surface rust within weeks if the steel is not rinsed and dried before storage. Boxes pulled from inland holding lots in late summer often have wasp nests in the corner castings and bird droppings on the roof. The cleaning playbook has to flex.

Why does a used shipping container need cleaning before you use it?

A used shipping container needs cleaning before service for three reasons, and they map to different risk levels: hygiene, coating adhesion, and health. Start neutral and every later step (storage, painting, conversion) works better.

The first is hygiene. Cargo residue, mouse droppings, and standing water from condensation pooling all become odour sources and pest attractants. A box that is going to store fabric, paper, food packaging, or anything porous needs to start neutral. Skipping this step means the next cargo absorbs the previous one.

The second is adhesion. Paint, epoxy floor coatings, spray foam insulation, and adhesive-mounted finishes all fail on contaminated surfaces. The factory marine paint on a used box is overlaid with diesel film, grease, salt, and sometimes a thin layer of mould-release wax from cargo packaging. Coatings applied over that combination peel in the first hot summer. If you are planning to cut doors, windows, or insulation into the unit, the cleaning step is what makes those yard-built conversion upgrades stick.

The third is health. The plywood floors used in CSC-certified containers are treated with insecticides to satisfy phytosanitary requirements at international ports of entry. Those compounds keep working for years after the box leaves the factory. For a tool-storage shed that gets opened daily, exposure is low. For a sealed home office, a backyard sauna, or anywhere children spend time, the floor question becomes a real decision.

Are shipping container floors treated with pesticides?

Yes. Shipping container floors are treated with pesticides, and this is the part of container cleaning work most resellers will not walk you through. Every CSC-certified shipping container leaves the factory with a wood floor made of tropical hardwoods such as Keruing or Apitong, glued and pressed into 28 millimetre marine plywood. Before the floor goes into the box, the wood is treated with insecticides. The two compounds most commonly cited in industry documentation are Basileum SI-84 (a permethrin and propiconazole blend) and Tributyltin Oxide on older units. The purpose is simple: keep wood-boring insects from riding the box from one continent to another.

These treatments are persistent. Tropical hardwood plywood off-gasses for years, and depending on the original treatment lot, the surface can still read positive on chemical tests a decade after manufacture. For a storage container, this is largely an academic concern. For a sealed conversion, the kind of office, cabin, or studio build that closes the box up tight, it matters more.

You have four practical options for the treated floor. The table below lays them out without dollar figures, since the right call depends on your end use, not a sticker price.

Health Canada’s Pest Management Regulatory Agency does not regulate aftermarket container floors directly, since the treatment happens overseas under the originating country’s phytosanitary code. The Canadian Food Inspection Agency’s wood packaging rules cover entry of treated wood but again focus on import compliance, not end use. The honest framing is this: the wood is safe enough to ship cargo, and unsafe enough that you should not eat off it. Sealing or replacement is the right call for any conversion where people will live, work, or eat.

How do you decontaminate a container interior, step by step?

Decontaminating a container interior follows seven steps, from dry removal through the floor decision. This is the procedure we walk customers through when they ask. It assumes a 20 foot or 40 foot dry box that has been emptied, swept, and parked on level ground with the doors open for ventilation. Plan a full day for a 20 foot unit and a day and a half for a 40 foot.

Step 1, dry remove. Sweep out loose debris, dust, and old desiccant pouches. Remove any cargo securement straps, tape, or stickers from the walls. A 6 inch plastic putty knife clears tape adhesive without scratching the paint. Bag and bin everything.

Step 2, dry vacuum. A shop vac on the floor, walls, and ceiling pulls out the fine particulate that the broom misses. Pay attention to the corrugation valleys on the walls. They are where diesel soot and salt collect.

Step 3, hot water pressure wash. A 3,000 PSI pressure washer with a 25 degree fan tip is the right tool. Start at the back wall and work toward the doors so water drains out. Hit the ceiling first, then walls, then floor. Avoid the door seals at full pressure. If you have a hot water unit, set it to 60 degrees Celsius. Cold water still works but takes longer to cut grease.

Step 4, degreaser application. Mix a citrus or soy-based degreaser to label dilution. Spray on, let dwell five minutes, agitate with a stiff brush on a pole, then rinse. Repeat in problem areas (door tracks, corner posts, the threshold where forklifts load and unload).

Step 5, mildewcide. Spray a quaternary ammonium or hydrogen peroxide based mildewcide on the ceiling and upper walls. Let dwell to label instructions and rinse. This kills mould spores that survived the wash.

Step 6, dry. Open both ends if you have double doors, or run a fan into the open end if you have a single. Drying takes 24 to 48 hours depending on humidity. Do not seal or paint over a damp interior. Trapped moisture under a coating causes blistering within months and creates the perfect environment for new mould.

Step 7, floor decision. At this point you choose: seal, overlay, or replace. The next sections cover each.

Which degreaser and solvent should you use on a container?

The right degreaser for a shipping container depends on the cargo history, and three categories cover most jobs. Not every degreaser is appropriate for a shipping container.

Citrus and soy-based bio-degreasers are the workhorse. D-limonene blends cut diesel film, light oil residue, and adhesive marks. They are biodegradable, low-odour, and safe for skin contact at use dilutions. Brands available in Ontario through industrial supply houses or farm co-ops include CRC, Krud Kutter, and Simple Green Pro. Mix to roughly 1:10 with warm water for general cleaning, full strength for stubborn spots.

Petroleum-based parts-washer solvents handle the heavier loads: hydraulic fluid drips, transmission oil, machinery grease. Use these in well-ventilated conditions with nitrile gloves and a respirator. They are appropriate where biodegreasers have been tried and failed. Apply with a brush, let dwell three minutes, wipe with absorbent rags, then rinse with detergent and water.

Quaternary ammonium sanitizers (the same chemistry used in food processing plants) are the right tool for biological contamination: animal droppings, food residue, blood from agricultural cargo. They kill on contact and break down to harmless ammonium salts. Follow label dwell times. They are not degreasers, so they go after the pressure wash, not before.

What to avoid: muriatic acid (eats galvanized fittings and door hardware), straight chlorine bleach (oxidizes paint and corrodes steel), and high-VOC industrial strippers (overkill on most boxes and leaves a residue that interferes with later coatings).

How do you prep a container floor before paint, epoxy, or vinyl?

Prepping a container floor before any finish means confirming the deck is clean and dry, then matching prep to the coating you have chosen. If the original plywood is staying, prep is everything. A clean dry floor is the start. Then you check moisture: tape a square foot of polyethylene plastic to the floor with painter’s tape, leave it 24 hours, and lift it. If the underside is dry and the plywood underneath has not darkened, you are below 4 percent moisture and ready to coat. If there is condensation under the plastic, the floor needs more drying time.

For epoxy systems, sand the plywood with 80 grit on a random-orbit sander to break the original wax-impregnated finish. Vacuum thoroughly. Apply an epoxy bonding primer at the rate the manufacturer specifies (typically 200 to 250 square feet per gallon). Let cure 8 to 24 hours depending on the product. Then apply two coats of high-solids epoxy floor paint, allowing full cure between coats. Total cure to walk-on is around 24 hours; full chemical cure is around seven days.

For vinyl flooring, install a 6 millimetre underlayment of moisture-resistant plywood over the original floor, screw it down on a 12 inch grid, and lay your vinyl tile or sheet vinyl on top. This is the approach we see most often in office conversions because it is forgiving of small floor irregularities and you can replace damaged sections later.

For new plywood replacement, pry up the original deck (it is screwed to the cross-members with self-tappers from the underside; access is through the cross-member gaps with a long screwdriver or by drilling the heads off from above). Lay new 18 to 19 millimetre marine-grade Douglas fir or spruce plywood. Coat with a clear penetrating sealer like a marine-grade epoxy or polyurethane. Then your finished surface. This option costs the most in time and material, but it is the cleanest baseline. For deeper detail on tearing out and rebuilding the deck, our step-by-step on pulling and rebuilding the deck walks through every fastener.

Can you convert a shipping container to food-grade in Ontario?

You can convert a shipping container for food use in Ontario, but it happens at a certified food-grade fabricator, not off the lot. This is the section where most container vendor websites get vague. The honest version is short. Van Blanc does not certify food-grade in-house. We supply containers; we do not run a food-grade fabrication line.

If you need a container converted for food storage, preparation, or processing, you have two practical paths. Path one is to buy the container from us, then take it to a certified food-grade fabricator. There are three or four specialty shops in Ontario that do this work properly: stainless steel interior cladding, food-safe coatings, sealed seams, certified ventilation, and the paperwork that satisfies a CFIA-licensed buyer.

Path two is to start with a one-trip container instead of a used one. A one-trip box has carried one load of cargo (usually clean dry goods like furniture or electronics) and has a near-factory interior. The industry calls these one-trip because the box made exactly one loaded voyage from the factory. It still has the pesticide-treated floor, so the food-grade fabricator will overlay or replace it, but the steel walls are clean and easier to clad. Most food-grade conversion shops prefer to start with a factory-clean box straight off its single voyage for this reason.

The CFIA’s Safe Food for Canadians Regulations (SFCR) cover the labelling and traceability side of food handling, not the structural certification of the container itself. The certification you actually want from a vendor is from the fabricator: documentation that the interior surfaces are food-contact safe, that any insulation is closed-cell and non-friable, and that the floor system is sealed against bacterial intrusion. Anyone selling you a “food-grade certified” container straight off the lot without modification is selling you marketing language, not certification.

For lighter food-adjacent uses (a coffee shop, a brewery taproom, a farm market stand) the bar is lower. You are not handling raw protein or open-air processing. A sealed and painted interior with vinyl flooring and food-safe surfaces on the prep zones is usually sufficient. We have helped owners planning a shipping container kitchen build work through this distinction.

Where does CFIA actually fit into container food use?

CFIA fits in on the food business, not the container. The Canadian Food Inspection Agency oversees food labelling, traceability, and import certification. It does not, as of 2026, run a “food-grade container” certification program. What it does regulate is:

Imported wood packaging materials, including pallets and dunnage, under the ISPM-15 standard. This is the rule that requires heat treatment or methyl bromide fumigation stamps on shipping wood. It applies to the wood, not the container.

The condition under which food can be shipped, stored, and labelled, under the SFCR. If you are operating a licensed food business out of a container conversion, your kitchen and storage need to meet the same standards as a brick-and-mortar facility. The container is the building. The container is not the certifying authority.

So when you see a vendor claiming “CFIA-approved containers,” what they should mean is that the container has been converted by a fabricator whose documentation will satisfy a CFIA inspector during your business licensing. Always ask for the fabricator’s documentation, not the vendor’s marketing copy.

How do you wash the exterior and prep rust spots?

Washing a container exterior is a flush-first, soap-second job, and rust spots get treated separately. The outside of a used container needs different work than the inside. Salt is the main enemy. Boxes that came off ocean routes carry chloride residue that, left in place, accelerates pitting corrosion at every paint chip.

A high-volume rinse with clean water is the first step. Skip the soap on the first pass: you want to flush the salt out of the corrugations and door tracks. Then a mild detergent wash with a long-handled brush gets the diesel soot off the roof and the algae streaks off the side walls. Rinse again and let dry.

Rust spots get treated next. Wire-brush surface rust to bright metal. Apply a rust converter (phosphoric acid based, like Ospho or Corroseal) to convert any pitting residue to an inert iron phosphate. Then prime with a marine-grade alkyd or two-part epoxy primer, and topcoat with an industrial alkyd or polyurethane in the colour you want. For keeping that corrosion from creeping back after you paint, our guide on stopping corrosion before it spreads runs the full sequence.

Roof cleaning deserves attention. The roof is the area most likely to have standing water, accumulated bird droppings, and the heaviest UV exposure. A pressure wash from a roof-mounted position (use a ladder and a non-skid pad, never walk on a wet container roof) followed by a roof-specific elastomeric coating extends paint life and reduces interior heat gain.

How do you remove odours from a used container?

Removing odours from a used container starts with the wash sequence and ends, for stubborn smells, with ozone or floor sealing. Smell is the last cleaning challenge and often the most stubborn. Containers absorb odours into the plywood floor, the rubber door seals, and any porous adhesive residue on the walls. Coffee, spice cargo, and tobacco are the worst offenders. Petroleum and solvent smells fade faster but linger in floor wood.

The cleaning sequence above (pressure wash, degrease, mildewcide, dry) handles most odours. For stubborn ones, ozone treatment is the next step. A commercial ozone generator runs sealed inside the container for 12 to 24 hours, breaking down volatile organic compounds at the molecular level. Air out for another 24 hours before entering. Ozone is hard on rubber seals at high concentration so use the lowest effective dose.

For floor-trapped smells specifically, the only durable fix is sealing or replacement. An odour that has soaked into 28 millimetres of tropical hardwood plywood is not coming out with surface treatment. Seal it with a high-build epoxy or overlay with vinyl.

Activated charcoal sachets and odour-absorbing gels help maintain a clean smell during use but they are maintenance tools, not remediation tools. Use them after cleaning, not instead of it.

What cleaning mistakes do Ontario container buyers make?

Ontario container buyers make the same six cleaning mistakes repeatedly, and most trace back to rushing the prep. After 30 years in this trade, we see them during the cleaning and prep stage again and again.

The first is sealing over wet floors. A coating goes on, looks great for a week, and blisters across an entire 20 foot deck by the following spring. Moisture-meter the plywood before any coating.

The second is skipping the degreaser step. Pressure water alone does not remove the wax-impregnated finish on factory plywood or the diesel film on the walls. Paint applied directly fails inside 18 months.

The third is using bleach on the interior. It feels like the strongest cleaner available, and it is, but it oxidizes paint, corrodes door hardware, and leaves a chloride residue that promotes rust. Use mildewcide instead.

The fourth is ignoring condensation. A freshly cleaned container that gets sealed up without ventilation will sweat heavily on the first cold night. Read why a sealed box sweats on the first cold night before closing up a clean unit.

The fifth is over-cleaning. You do not need to remove every blemish, every original marking, or every shadow on the steel. The structural condition of the box and the integrity of the floor matter more than cosmetic perfection. Spending 40 hours making a storage box look like new is bad economics.

The sixth is buying without inspection. The cleaning load on a box you have not seen is unpredictable. A photo from a vendor cannot tell you whether the floor is stained from beans (easy) or from agricultural pesticides (hard). For 200 plus boxes in our four Brantford yards, every customer is welcome to walk the row, look inside, and pick the box that already cleans up best. Most Ontario container suppliers do not let you choose. We do. When you are ready to walk the rows and pick your own unit, knowing the cleaning load up front saves you hours at home.

Christian on why inspection sets the cleaning job

Knowing the box you are starting from also tells you which container size suits the job. If you are still deciding between a 20 foot and a 40 foot, our breakdown of how the standard box dimensions compare lines up interior space against the cleaning and finishing effort each size demands.

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

If you are planning a conversion that needs a clean starting point, walk our yard before you commit. With 200 plus boxes in inventory, you can pick the unit that already looks closest to where you want to end up, which saves you hours of cleaning later. Most Ontario container suppliers do not let you choose. We do.

Sources and further reading

• International Organization for Standardization. ISO 6346:2022 Freight containers, coding, identification and marking.
• Canadian Food Inspection Agency. Shipping containers labelling and Safe Food for Canadians Regulations.
• Canadian Food Inspection Agency. Wood packaging questions and answers, ISPM-15.
• Discover Containers. Shipping Container Flooring and Pesticides.
• DryboxUSA. How to Clean a Shipping Container: 4 Easy Steps.

Related Reading

• rebuilding a worn-out deck
• keeping rust from coming back
• lease versus buy for a fleet
• stacking boxes safely
• fire safety in a converted box
• what your box is worth later