What should not be stored in a shipping container

Steel conducts heat quickly. This means the inside of a container can become hot in summer, cold in winter, and humid when warm moist air meets cold steel. Condensation can form on the roof, walls, doors, floor, and stored goods. This is often called container rain.

The main risks are moisture damage, mould, corrosion, fumes, fire, pest activity, odour transfer, contamination, insurance exclusions, and non-compliance with rules for hazardous or regulated goods. Before storing anything sensitive, valuable, perishable, flammable, or controlled, check whether a standard dry container is suitable.

Items to avoid in a standard shipping container

Some goods should not be placed in a standard container unless a competent person has confirmed the correct specification, ventilation, containment, access control, and legal requirements. The following categories need caution.

• Flammable liquids and fuels: petrol, solvents, thinners, some paints, oils, and fuel cans can create fire, vapour, spill, and insurance risks.
• Gas cylinders: cylinders can create pressure, ventilation, impact, fire, and handling risks if stored incorrectly.
• Explosives and pyrotechnics: fireworks, ammunition, and explosive materials require specialist storage and legal checks.
• Chemicals and pesticides: toxic, corrosive, reactive, or environmentally harmful products may need bunding, ventilation, segregation, signage, and controlled access.
• Lithium batteries: damaged, high-capacity, or poorly stored batteries can create fire and heat risks.
• Perishable food and plants: these can rot, attract pests, create odours, and become unsafe without temperature and hygiene control.
• Medicines and temperature-sensitive goods: these may need monitored temperature control and specialist compliance.
• Wet goods: damp timber, wet textiles, wet cardboard, and recently washed equipment can cause rapid condensation and mould.

General UK government information can be checked at gov.uk, but storage duties should be confirmed with the relevant authority, insurer, safety adviser, or competent professional.

Damp-sensitive goods need extra protection

Paper, books, archives, clothes, bedding, mattresses, upholstered furniture, fine art, musical instruments, leather goods, electronics, and untreated timber can suffer in a standard steel container if moisture is not controlled.

These items may still be stored in a container, but they need a suitable storage plan. This may include dry loading, sealed boxes, desiccants, raised storage, racking, airflow gaps, passive vents, extra ventilation, lining, insulation, anti-condensation treatment, or dehumidification.

A lined container has an internal surface fitted over the steel. Insulation reduces heat transfer and can help reduce the risk of condensation when combined with suitable ventilation. Neither lining nor insulation removes the need to load dry goods and inspect them regularly.

For moisture-control options, see insulation options for shipping containers.

Hazardous goods and chemicals

Hazardous goods should not be stored in a basic dry container without checking the exact substance, quantity, packaging, ventilation, spill containment, fire risk, segregation, access control, and legal duties. This includes flammable liquids, corrosive chemicals, pesticides, fertilisers, cleaning chemicals, aerosols, gas cylinders, fuel, and some workshop products.

A bunded container may be needed where liquids could leak or spill. Bunding is secondary containment that helps prevent liquid from escaping into the environment. Some materials may also need high and low-level ventilation, fire separation, warning signage, restricted access, temperature control, or specialist cabinets inside the container.

Acorn Containers can discuss container types and modifications, but hazardous material storage is a safety and compliance decision. Check with the relevant regulator, fire safety adviser, insurer, site duty holder, or competent professional before storing hazardous substances.

Food, animal feed and perishables

Standard dry containers are usually not suitable for perishable food, chilled products, frozen goods, fresh produce, medicines, or goods that need controlled temperature. These items can spoil quickly and may attract rodents, insects, or birds, or lead to contamination if not stored correctly.

Animal feed can also be sensitive to moisture and pests. If feed becomes damp, it may spoil, attract vermin, or become unsafe for use. Dry-packaged goods may require pallets, racking, airflow, pest control, and regular inspection.

A refrigerated container, also called a reefer, provides temperature control when connected to a suitable power supply. It still needs loading controls, airflow space, monitoring, cleaning, maintenance, and suitability checks for the goods stored.

For temperature-controlled options, see 20ft refrigerated containers and 40ft refrigerated containers.

High-value goods and insurance-sensitive storage

High-value tools, plant, retail stock, documents, electronics, bikes, machinery, and customer goods should not be stored without checking insurance and security requirements. A container can be secure, but no storage method eliminates the risk of theft or damage.

Security may need a lockbox, a suitable padlock, controlled key access, lighting, CCTV, alarms, fencing, regular inspections, and careful door orientation. A lockbox is a steel cover that shields the padlock from direct attack.

Insurance terms may specify locks, alarms, location, declared value, unattended periods, fire risk, moisture control, stock records, and reporting procedures. Check your policy before storing valuable goods, especially on remote, temporary, shared, or unstaffed sites.

Vehicles, machinery and powered equipment

Vehicles, motorbikes, lawn mowers, generators, and machinery are often stored in containers, but they need to be checked before loading. Fuel, oil, batteries, tyres, fumes, leaks, floor loading, ramps, ventilation, and insurance all matter.

Do not store leaking equipment or fuel containers casually inside a standard unit. Even small leaks can create fumes, fire risk, slip hazards, odour, contamination, and damage to the floor. Batteries should be stored according to the manufacturer’s instructions and any insurer or site rules.

Heavy machinery may require a 20ft container, flat rack, open-top container, or purpose-planned loading method, depending on dimensions and weight. A flat rack container is used for oversized, heavy, or awkward cargo. An open-top container allows goods to be loaded from above.

For specialist handling, see flat-rack containers and 20ft open-top containers.

What is usually safe to store?

Many robust, dry, non-perishable goods are suitable for standard container storage when the container is in good condition and placed correctly. Examples include dry building materials, tools, scaffolding fittings, garden equipment, event equipment, sports kit, metal parts, machinery spares, workshop items, and well-packed household goods.

Even suitable goods should be loaded with care. Keep items dry, raise them off the floor where practical, avoid blocking vents, leave airflow gaps, and inspect the container after bad weather or long periods of closure. Use racking or shelving where regular access is needed.

For general storage sizes, see 20ft shipping containers and 40ft shipping containers.

Sale, hire and modifications

Hire can work well for short-term building projects, renovations, events, seasonal stock, and temporary overflow storage. Buying may be better for long-term storage, business assets, modification, branding, specialist fittings, or repeated use.

If you hire a container, do not drill vents, fit electrics, add coatings, install racking, store hazardous goods, or make permanent changes without agreement. Hire terms may restrict what can be stored and how the container can be used.

Common modifications include extra vents, lining, insulation, anti-condensation coating, racking, shelving, lockboxes, personnel doors, electrics, lighting, and refrigerated systems. The right option depends on the goods, site, duration, access, insurance, and compliance requirements.

Compare options through container sales and container hire.

Site placement can affect stored goods

Where the container is placed can make storage risks worse or better. A damp, shaded, poorly drained site can increase the risk of condensation and corrosion. A hot, exposed site can increase temperature swings. A remote site can increase the risk of theft.

Place the container on firm, level, well-drained ground. Concrete, tarmac, compacted stone, or prepared hardstanding is usually more suitable than wet grass, mud, or soft soil. Uneven ground can twist the frame and affect door seals, which may allow water ingress or make the doors hard to lock.

Check delivery access before ordering. Most deliveries need a heavy goods vehicle, and many placements use a HIAB. A HIAB is a lorry-mounted crane used to lift and place the container. The site needs suitable access, overhead clearance, stabiliser space, and ground conditions.

For delivery planning, see container delivery.

Export and business compliance risks

If goods are being stored before export, the container may need to be cargo-worthy, have a valid CSC status, be cargo-secured, have moisture-control planning, include customs documents, have insurance, and be accepted by the carrier. A wind and watertight storage container should not be assumed suitable for export cargo.

Incoterms 2020 are trade terms published by the International Chamber of Commerce that define the responsibilities between the buyer and the seller. They can affect transport, insurance, risk transfer, export clearance, import clearance, and delivery obligations.

Acorn Containers can advise on container suitability and delivery planning, but legal, tax, customs, insurance, hazardous goods, and trade compliance matters should be checked with the relevant authority, freight forwarder, customs agent, insurer, or trade adviser. For background, use Incoterms 2020, trade.gov.uk, and iccwbo.org.

Storage suitability checklist

Use this checklist before placing goods in a standard shipping container.

• List every item or product category being stored.
• Identify moisture-sensitive, temperature-sensitive, high-value, hazardous, perishable, or regulated goods.
• Check whether any goods need ventilation, bunding, refrigeration, fire separation, pest control, or specialist storage.
• Confirm whether insurance covers the goods in a container at the chosen site.
• Make sure all goods are dry before loading.
• Raise goods on pallets, shelving, or racking where practical.
• Leave airflow gaps around walls, doors, and vents.
• Keep chemicals, fuels, batteries, food, and medicines out of a standard unit unless suitability has been checked.
• Choose a suitable container size, condition grade, and modification package.
• Check site drainage, ground level, delivery access, overhead obstructions, and security.
• For export or regulated goods, check requirements with the relevant adviser or authority before loading.

Information to provide before requesting a quote

Clear details help Acorn Containers recommend the right unit and avoid unsuitable storage.

• Confirm whether you want to buy, hire, or compare both options.
• Confirm the container size being considered, such as 10ft, 20ft, 40ft, or high cube.
• Describe the goods, including any chemicals, fuel, batteries, food, documents, furniture, tools, stock, machinery, or export cargo.
• Confirm whether goods are valuable, insured, regulated, temperature-sensitive, moisture-sensitive, or perishable.
• List needs for ventilation, lining, insulation, anti-condensation treatment, bunding, racking, refrigeration, electrics, or security.
• Provide the delivery postcode, full address, site contact, and access details.
• Describe the ground surface, drainage, shade, overhead hazards, door clearance, and site security.
• For export, provide cargo details, destination, loading plan, freight forwarder details, and documentation requirements.
• Check legal, safety, insurance, tax, customs, and compliance responsibilities with the relevant authority or professional.