Keeping a Used 20ft Container Rust-Free: Maintenance Guide

A used 20ft container is built to handle years at sea, so on land it can last a very long time, if you keep rust in check. Rust doesn't happen overnight. It starts where water sits and steel is exposed, and a little maintenance stops it before it becomes a hole.

Here's how to keep a used 20ft container rust-free, from where you put it to a simple yearly routine. If you're still choosing one, our used 20ft shipping containers for sale are graded so you know what condition you're starting with.

Where rust starts

• The roof: dents collect water, which sits for days after rain
• The bottom rails: close to the ground, where they stay damp
• The cross members under the floor, if the container sits on wet ground
• Scratches and chips where the paint has worn through
• Around the doors: hinges, locking gear and the door frame
• Inside, from condensation dripping from the ceiling

Step 1: Place it right

Good placement prevents most rust:

• Off the ground: on a gravel pad, blocks or railroad ties, so air moves underneath
• Level: so water runs off the roof and doors seal properly
• A slight fall toward the doors, if your site allows, so roof water drains away
• On high ground, away from puddles and runoff
• Away from sprinklers that spray the container daily
• Clear of overhanging trees, which drop leaves on the roof and keep it damp

Step 2: Look after the roof

• Clear it of leaves, branches, snow and standing water after storms and in each season
• Push out dents that collect water, from inside with a jack and timber
• Treat rust in dents promptly
• Consider a roof cover, such as a simple pitched roof or shade structure, for long-term placements

Step 3: Treat rust spots

When you find rust:

1. Wire brush or sand back to bright, sound metal
2. Clean away dust and grease
3. Apply a rust-converting or rust-inhibiting primer
4. Paint with a paint suitable for steel and outdoor exposure

Do this in dry, mild weather, following the paint's instructions.

Step 4: Keep the paint in good shape

• Touch up scratches as soon as you notice them
• Repaint when the finish becomes chalky, thin or patchy
• Use light colors in hot climates to reduce heat and condensation

Step 5: Maintain the doors

• Grease hinges and locking gear once or twice a year
• Check door gaskets and replace them if they're hard or torn
• Keep the doors closed in rain so water doesn't pool on the floor

Step 6: Control condensation inside

• Add vents for airflow
• Keep stored goods off the floor
• Use desiccants in humid climates
• Consider insulation for sensitive storage

Coastal and humid areas

Salt air and humidity speed up rust. In these areas:

• Rinse the container with fresh water now and then to remove salt
• Check for rust more often, at least twice a year
• Choose a container with sound paint to begin with

A yearly maintenance plan

When rust has gone too far

If rust has eaten through the roof or walls, the damaged steel can be cut out and a new steel patch welded in. Scaling rust on the rails or cross members is structural and needs professional assessment.

Tools and supplies for container upkeep

• A stiff wire brush and sandpaper
• Rust-inhibiting primer
• Outdoor paint suitable for steel
• A roller and brush for corrugated walls
• Grease and penetrating oil for hinges and locking gear
• Replacement door gaskets, if needed
• A ladder for safe roof checks

FAQ

How do I stop a shipping container from rusting?

Keep it level and off the ground, keep the roof clear, treat rust spots promptly and keep the paint in good condition.

Is surface rust on a used container a problem?

Not at first. Treat it before it spreads or eats through.

What paint should I use on a container?

A paint suitable for steel and outdoor exposure, over a rust-inhibiting primer on any bare or rusted metal.

How often should I check my container for rust?

At least once a year, and twice a year near the coast or in humid areas.

Can a rusty container be saved?

Usually. Surface rust is easy to treat, and holes can be patched with welded steel.

Does a roof cover help prevent rust?

Yes. A simple roof or shade structure keeps water off the container's roof, where rust usually starts.

Should I paint the inside of my container too?

Only where you see rust or bare metal. Interior rust usually comes from condensation, so add vents and keep goods off the floor as well.