Portable storage containers are steel, ground-level units used to securely store equipment, materials, and supplies directly on jobsites and commercial properties.
They are commonly available in 20-foot and 40-foot sizes, including high cube options for added interior height, and can be rented or purchased new or used.
This guide explains container sizes, condition types, delivery requirements, security features, and common jobsite uses to help businesses choose the right portable storage solution with confidence.
What is a portable storage container?
A portable storage container is a durable steel unit designed for secure, on-site storage of tools, materials, and equipment.
Unlike warehouse storage or storage trailers, portable storage containers are delivered directly to your location and placed at ground level, allowing easy access throughout the project.
These containers are widely used on construction sites, commercial properties, schools, retail locations, and industrial facilities where space, security, and convenience matter. Their rugged construction helps protect contents from weather exposure and theft while keeping materials close at hand.
Container terminology clarification
The storage industry uses several terms that often refer to the same product:
Storage container refers to any portable container used for storing items at a location. This is the broadest term and includes both new purpose-built units and repurposed shipping containers.
Conex box is military terminology from “Container Express,” originally used for shipping military supplies. Many people still use this term, though it technically refers to specific military-spec containers. In common usage, it means any portable storage container.
Shipping container specifically describes containers designed and certified for international cargo transport. When used for storage, these are repurposed from their original shipping function.
Storage trailer refers to containers mounted on wheels or chassis for towing. These differ from standard storage containers because they include transportation capability but often provide less security and weather protection than ground-level steel containers.
Portable storage unit encompasses all movable storage solutions, including containers, trailers, and pods. This general term doesn’t specify construction type or capabilities.
For jobsite storage, the terms “storage container,” “shipping container,” and “conex box” typically describe the same product: a steel container placed on the ground for secure storage.
What sizes of portable storage are available?
Portable storage containers come in standardized sizes based on shipping container dimensions. The most common sizes for jobsite and commercial storage are 20-foot and 40-foot containers.
20-foot containers
A 20-foot container measures approximately 20 feet long, 8 feet wide, and 8.5 feet tall on the exterior. Interior dimensions are slightly smaller, typically 19’4″ long, 7’8″ wide, and 7’10” tall. This provides roughly 160 square feet of floor space.
These containers hold approximately 1,100 cubic feet of storage volume. Common uses include small to medium residential projects, temporary equipment storage, and situations where site access limits larger container delivery.
40-foot containers
A 40-foot container measures approximately 40 feet long, 8 feet wide, and 8.5 feet tall on the exterior. Interior dimensions typically measure 39’5″ long, 7’8″ wide, and 7’10” tall, providing approximately 320 square feet of floor space.
Storage volume reaches approximately 2,350 cubic feet. These containers work well for large commercial projects, extended construction timelines requiring substantial equipment storage, and operations needing to consolidate multiple storage needs into one unit.
High cube containers
High cube containers match standard container lengths (20′ or 40′) but stand one foot taller. External height measures 9.5 feet instead of 8.5 feet, with interior height around 8’10”.
The additional height provides extra vertical storage space without requiring additional ground footprint. This benefits operations storing tall equipment, stacked materials, or items requiring overhead clearance for loading and unloading.
10-foot and custom sizes
Some providers offer 10-foot containers measuring 10 feet long, 8 feet wide, and 8.5 feet tall. These smaller units work for residential projects with limited space or situations where site access prevents larger container delivery.
Custom modifications can create specialized sizes, though these typically cost more than standard containers. Most jobsite applications work well with standard 20-foot or 40-foot dimensions.
What’s the difference between new and used containers?
Container condition directly affects pricing, appearance, durability, and suitability for different applications. Providers typically categorize containers as new (one-trip), cargo worthy, wind and watertight (WWT), or as-is.
New containers (one-trip)
New containers, often called “one-trip” containers, have made a single voyage from the manufacturing facility (typically in China) to the United States. These containers are approximately 3-6 months old and show minimal wear.
Exterior paint remains intact without significant scratches, dents, or rust. Doors operate smoothly with properly functioning locking mechanisms. Floors show no damage, and the container maintains structural integrity throughout.
New containers cost 30-50% more than used options but provide the longest service life and best appearance. They work well for long-term installations, customer-facing locations, or situations requiring pristine condition.
Cargo worthy containers
Cargo worthy certification means a container meets International Convention for Safe Containers (CSC) standards for shipping cargo internationally. Certified inspectors examine structural integrity, door functionality, floor condition, and weatherproofing.
These containers safely hold cargo during ocean transport, which requires passing strict safety and structural standards. Cargo worthy containers typically show some cosmetic wear from shipping use but maintain excellent structural condition and weatherproofing.
For storage applications, cargo worthy containers provide reliable weather protection and security at lower cost than new units. They’re 5-15 years old on average but remain fully functional.
Wind and watertight (WWT) containers
Wind and watertight containers provide weather protection without meeting cargo worthy certification standards. These containers keep out rain, snow, and wind but may show cosmetic damage like dents, scratches, surface rust, or faded paint.
Doors close and lock properly, floors remain solid and intact, and the container shell maintains weatherproofing. However, these units may have minor repairs, patch welds, or cosmetic issues that prevent cargo worthy certification.
WWT containers cost 20-40% less than cargo worthy units while still protecting contents from weather. They work well for jobsite storage where appearance matters less than functionality and cost savings.
As-is containers
As-is containers are sold without guarantees about condition. These may have significant rust, holes, damaged doors, compromised floors, or structural issues. They require inspection before purchase or rental.
While very inexpensive, as-is containers often need repairs to function properly for storage. Unless you have specific plans for a damaged unit, cargo worthy or WWT containers provide better value for reliable storage.
What does “cargo worthy” mean?
Cargo worthy certification indicates a container meets international safety standards for transporting cargo on ships. The certification process involves inspection by qualified inspectors who verify the container can safely carry loads during ocean transport.
Certification requirements
Inspectors examine several critical areas:
Structural integrity: The container frame, corner posts, and cross members must be free from significant corrosion, damage, or weakness that could compromise load-bearing capacity.
Floor condition: Floors must be intact without holes, significant rot, or soft spots. The flooring needs adequate strength to support cargo weight distributed across the floor area.
Door functionality: Both doors must open and close properly with functioning locking mechanisms. Door seals must be intact to prevent water intrusion.
Weatherproofing: The container must prevent water entry during ocean transport. Inspectors check for holes, gaps, damaged seals, and compromised welded seams.
CSC plate: A valid CSC (Convention for Safe Containers) safety approval plate must be attached, showing the container’s manufacturing date, maximum weight ratings, and inspection history.
Containers passing inspection receive cargo worthy certification valid for varying periods depending on the inspection results and container age.
Relevance for storage applications
For jobsite storage, cargo worthy certification provides assurance about structural condition and weatherproofing. If a container can protect cargo during ocean voyages—where it faces salt spray, rough seas, and stacked loading—it will certainly protect construction materials and equipment on the ground.
However, many excellent storage containers don’t have current cargo worthy certification because they’ve aged beyond shipping use or have cosmetic issues that don’t affect storage function. Wind and watertight containers often provide equivalent protection for storage applications at lower cost.
Are storage containers weatherproof?
Storage containers provide excellent weather protection when properly maintained and in good condition. The level of weatherproofing varies based on container age, condition, and maintenance.
Weather protection features
Steel construction: Corrugated steel walls and roof shed water effectively. The corrugation adds structural strength while creating channels that direct water runoff away from seams.
Raised floor: Container floors sit several inches above ground level, preventing ground water from entering even during heavy rain or snow melt.
Door seals: Rubber gaskets around door frames create weathertight seals when doors close properly. These seals prevent rain and wind from entering through door gaps.
Welded seams: Container walls connect through welded seams that prevent water intrusion when properly maintained.
Weatherproofing considerations
Container weatherproofing depends on condition. New and cargo worthy containers provide excellent protection against rain, snow, and wind. Doors seal tightly, and the steel shell remains intact without holes or compromised seals.
Wind and watertight containers also prevent weather intrusion but may have minor imperfections. Small surface rust spots don’t typically affect weatherproofing, though they may expand over time without treatment.
Older containers or those in poor condition may develop leaks from rust holes, damaged door seals, or compromised roof seams. Inspecting containers before use prevents surprise moisture problems.
Condensation management
Even weatherproof containers can experience condensation. When warm, humid air inside contacts cold steel walls, moisture condenses on interior surfaces. This happens most commonly during temperature changes between day and night or seasonal transitions.
Condensation doesn’t indicate poor weatherproofing—it’s a natural occurrence in any enclosed steel space. Ventilation helps manage condensation for sensitive materials. Some containers include passive vents, or users can add ventilation systems for climate-sensitive storage needs.
How are containers delivered to a jobsite?
Container delivery requires specialized equipment and adequate site access. Understanding delivery requirements helps ensure successful placement without delays or additional costs.
Delivery methods
Tilt-bed truck (roll-off delivery): The most common delivery method uses a tilt-bed truck that tilts the bed, allowing the container to roll off onto the ground. This method requires approximately 60 feet of straight, level clearance—the truck length plus container length.
The truck backs into position, tilts the bed, and the container slides off using rollers or skids. This method works well for sites with good access and adequate space.
Crane delivery: When sites lack roll-off access, cranes can lift containers from flatbed trucks and place them precisely. This method allows placement in tight spaces, over obstacles, or in areas without straight access.
Crane delivery costs more than standard delivery due to equipment and operator expenses. It requires stable ground for crane positioning and overhead clearance for the crane boom and suspended container.
Side-loader delivery: Some providers use side-loader trucks with hydraulic arms that lift containers from the side and place them adjacent to the truck. This method works for sites with side access but limited front or rear clearance.
Site requirements for successful delivery
Access clearance: Roll-off delivery requires 60-100 feet of straight access depending on container size (20-foot or 40-foot). The route must be wide enough for the delivery truck, typically 10-12 feet minimum.
Overhead clearance: Check for power lines, tree branches, or building overhangs along the delivery route and placement location. Minimum 14 feet of vertical clearance prevents complications.
Ground conditions: Delivery trucks and loaded containers are very heavy. Soft ground, recent rain, or unstable surfaces can prevent delivery. Firm, level ground or gravel/concrete surfaces work best.
Slope limitations: Containers should be placed on relatively level ground. Excessive slope prevents proper door operation and can create interior drainage issues. Maximum recommended slope is typically 3-5 degrees.
Underground utilities: Verify no underground utilities exist where the container will sit. The weight of loaded containers can damage buried lines, pipes, or septic systems.
Permits and regulations
Some municipalities require permits for placing portable storage containers, especially for extended periods or in residential areas. Requirements vary significantly by location.
Commercial and industrial zones typically have fewer restrictions than residential areas. Duration affects requirements—temporary placement (30-90 days) often has different rules than long-term storage.
Check local zoning ordinances and homeowner association rules before scheduling delivery. Local storage providers familiar with the area can often advise on permit requirements.
What are common jobsite uses for portable storage containers?
Construction sites and commercial operations use portable storage containers for numerous applications beyond simple material storage.
Construction equipment and tool storage
Contractors store power tools, hand tools, and small equipment in containers to prevent theft and weather damage. Locking steel containers provide significantly better security than job trailers or temporary structures.
Tools remain organized and accessible without requiring trips to off-site storage. Crews access equipment at the start of each day without delays, and valuable tools stay protected overnight and over weekends.
Material and supply storage
Construction materials including lumber, drywall, electrical supplies, plumbing fixtures, and finish materials need protection from weather and theft. Containers keep these materials dry and secure until needed.
This prevents waste from weather damage, reduces theft losses, and eliminates reordering delays for damaged materials. Materials stay organized by project phase, making retrieval efficient when needed.
Secure document and equipment storage
Project documents, permits, blueprints, and sensitive equipment require secure storage. Containers provide lockable space for paperwork, computers, surveying equipment, and testing devices.
Climate-sensitive documents benefit from the dry storage environment, though very sensitive items may need additional climate control during extreme temperatures.
Temporary site office space
With modifications, containers can serve as temporary site offices. Adding windows, doors, insulation, electricity, and HVAC creates functional workspace. This works well for job trailers alternatives or superintendent offices.
Modified container offices provide better security than traditional job trailers and withstand harsh weather conditions. They can be relocated as project needs change.
Seasonal equipment storage
Between construction seasons or during project gaps, contractors store specialized equipment, scaffolding, safety gear, and seasonal tools. Containers protect expensive equipment from weather deterioration during storage periods.
This extends equipment life and reduces replacement costs. Seasonal storage containers can be placed at company yards or near frequently worked areas for convenient access.
Hazmat and chemical storage
Modified containers with proper ventilation, spill containment, and safety features store hazardous materials, paints, solvents, and chemicals. Steel construction contains spills better than wooden structures.
Proper modification and compliance with regulations is essential for hazmat storage. Not all containers are suitable for chemical storage without modifications.
Retail and merchandise storage
Commercial operations use containers for excess inventory, seasonal merchandise, and backup stock. Retail locations with limited back-room space benefit from on-site container storage.
Merchandise stays accessible without requiring warehouse rental or off-site trips to retrieve inventory. This improves operational efficiency while reducing storage costs.
How do delivery requirements vary by container size?
Larger containers require more access space, clearance, and site preparation than smaller units. Understanding size-specific requirements prevents delivery complications.
20-foot container delivery
Roll-off delivery of 20-foot containers requires approximately 60-75 feet of straight access. The delivery truck measures about 35-40 feet, and the container adds 20 feet, requiring combined clearance plus operating space.
Access width needs 10-12 feet minimum for the truck and container. Placement areas need 20 feet by 8 feet of relatively level, firm ground.
Weight when empty is approximately 5,000 pounds. Maximum loaded weight approaches 67,000 pounds, though storage use rarely reaches this limit. Even partially loaded containers are very heavy and require stable ground.
40-foot container delivery
Roll-off delivery of 40-foot containers requires approximately 100-120 feet of straight access. The delivery truck plus 40-foot container creates substantial length requiring clear access routes.
Access width requirements match 20-foot containers (10-12 feet), but turning radius limitations matter more for longer containers. Tight corners or narrow gates often prevent 40-foot container access.
Placement areas need 40 feet by 8 feet of level ground. Empty weight is approximately 8,000 pounds with maximum loaded weights reaching 67,000 pounds.
Many sites with adequate access for 20-foot containers cannot accommodate 40-foot deliveries. Evaluate access carefully before ordering larger containers.
High cube container considerations
High cube containers add one foot of height but maintain standard length and width dimensions. Delivery requirements match standard containers of the same length, but overhead clearance becomes more critical.
Ensure 14-15 feet of vertical clearance throughout the delivery route and placement area. Power lines, building eaves, and tree branches cause more problems with high cube containers than standard height units.
Crane delivery requirements
When roll-off delivery isn’t possible, crane placement provides alternatives. Crane delivery needs:
Crane positioning space: Firm, level ground for crane stabilization, typically 20-30 feet from the final container placement.
Overhead clearance: Full vertical clearance for the extended crane boom with suspended container, often 30-50 feet depending on crane size and placement distance.
Flatbed access: While the crane handles placement, a flatbed truck must still access the site to deliver the container to the crane location.
Crane delivery costs typically add $300-800 depending on crane size and placement complexity.
What security features do storage containers provide?
Portable storage containers offer multiple security layers that protect contents from theft and unauthorized access. Security effectiveness depends on container condition, lock quality, and site-specific factors.
Structural security
Steel construction: Heavy-gauge corrugated steel walls resist cutting, prying, and forced entry far better than wood structures or fabric enclosures. Breaking into steel containers requires specialized tools and considerable time and noise.
Solid floor: Steel or wood-over-steel floors prevent entry from underneath. Unlike raised structures, ground-level containers eliminate access from below.
Limited openings: Containers have only one entry point (double doors at one end), making them easier to secure than structures with multiple doors and windows.
Locking mechanisms
Lockbox installation: Many containers include or can add lockboxes—steel enclosures that protect padlocks from bolt cutter access. The lockbox covers the padlock, preventing cutting or prying.
Crossbar locks: Containers often feature locking bars that secure both doors simultaneously. This prevents prying doors apart even if hinges or lock mechanisms are attacked.
Padlock requirements: Container security depends heavily on padlock quality. Standard keyed padlocks provide basic security. Disc locks or shrouded shackle locks resist cutting better than standard padlocks.
Cargo door locks: Built-in locking rods run vertically through the door frame, securing doors at multiple points. These are part of the container’s original design and provide baseline security.
Security considerations and limitations
While containers provide excellent security, no storage solution is completely theft-proof. Determined thieves with power tools and sufficient time can breach any container.
Security effectiveness increases with:
Site visibility: Containers in visible, monitored locations deter theft better than isolated placement. Thieves prefer targets they can attack without observation.
Lighting: Well-lit areas make container break-ins riskier and more visible. Motion-activated lighting adds deterrence.
Multiple locks: Using multiple lock types simultaneously increases difficulty. Attackers need different tools and more time to defeat multiple security layers.
Alarm systems: Battery-powered container alarms detect door opening and sound loud alerts. These work well when someone can respond to alarms.
Ground anchoring: Containers can be anchored to prevent theft of the entire unit. While stealing entire containers is rare (they’re very heavy and conspicuous), high-value contents might justify this precaution.
Insurance and liability considerations
Even with good security, insuring valuable container contents provides financial protection. Many property insurance policies cover stored items, but verify coverage limits and requirements.
Document container contents with photographs and inventory lists. This simplifies insurance claims if theft occurs and helps track what’s stored where across multiple containers.
How do portable storage containers compare to other jobsite storage options?
Several storage solutions serve construction sites and commercial operations. Understanding how containers compare helps select the right option for specific needs.
Storage containers vs. job trailers
Security: Steel containers provide better theft protection than most job trailers. Trailer construction typically includes thinner materials and more potential entry points (windows, vents, access panels).
Weather protection: Containers generally offer superior weatherproofing. Quality job trailers also weatherproof well, but containers have fewer potential leak points and more durable construction.
Mobility: Job trailers include wheels and can be towed to new locations relatively easily. Moving containers requires delivery trucks or cranes, making trailers better for frequently relocated storage.
Interior environment: Job trailers often include insulation, climate control, and finished interiors suitable for office work. Standard containers lack these features unless modified, making trailers better for climate-controlled or office applications.
Cost: Containers typically cost less to rent than job trailers with similar square footage, especially for longer rental periods. Purchase prices vary widely based on features and condition.
Storage containers vs. portable storage pods
Capacity: Containers offer more storage volume than typical storage pods. A 20-foot container provides more space than most standard pods.
Security: Steel shipping containers provide better security than the lighter construction of most storage pods. Containers resist forced entry more effectively.
Weather protection: Both provide good weather protection when in good condition. Containers may offer slight advantages due to heavier steel construction.
Access: Pods often load through top access or end doors. Containers exclusively use end doors, which some users prefer for organization and accessibility.
Delivery flexibility: Pod companies often use specialized delivery vehicles with built-in lifting mechanisms, potentially accessing tighter spaces than standard container delivery trucks.
Cost: Costs vary by provider and market. Containers generally cost less for larger, longer-term jobsite storage needs.
Storage containers vs. off-site storage facilities
Convenience: On-site containers provide immediate access without requiring trips to storage facilities. This saves time and transportation costs when accessing stored items.
Security: Both options can be secure, but containers keep items under your direct control and supervision rather than at a third-party facility.
Cost: For jobsite storage, containers often cost less than renting equivalent space at storage facilities, especially when considering transportation time and expense.
Accessibility: Containers provide 24/7 access without facility hours or access restrictions common at storage facilities.
Climate control: Storage facilities often offer climate-controlled units. Standard containers lack climate control unless modified, making facilities better for climate-sensitive items.
Liability: With on-site containers, you control security and access. Storage facilities transfer some liability to the facility operator but also limit your control.
Storage containers vs. on-site buildings
Installation time: Containers arrive ready to use. On-site buildings require construction time, permits, and inspections before use.
Cost: Containers cost significantly less than permanent construction. Even temporary buildings typically cost more than container rental.
Portability: Containers can be removed when no longer needed. Permanent or semi-permanent buildings become property fixtures with different tax and property implications.
Customization: Buildings can be designed specifically for intended uses. Containers work best for applications fitting their standard dimensions and features.
Longevity: Permanent buildings last longer and maintain value better than containers. For temporary needs, containers make more sense. For permanent storage, buildings may be preferable.
What questions should you ask storage container providers?
Selecting a storage container provider requires understanding their service offerings, container quality, and terms. Asking specific questions reveals whether a provider meets your needs.
Container condition and specifications
What condition categories do you offer? Understand whether they provide new, cargo worthy, wind and watertight, or as-is containers. Clarify what each category means for their specific inventory.
Can I inspect the container before delivery? Some providers allow pre-delivery inspection. This helps verify condition matches descriptions and meets your requirements.
What are the exact dimensions of your containers? Confirm interior dimensions, not just exterior measurements. Interior space determines usable storage capacity.
Do containers include lockboxes or security features? Determine what security hardware comes standard and what costs extra.
Delivery and placement
What delivery methods do you offer? Confirm they can accommodate your site’s access limitations. Ask about roll-off, crane, or side-loader delivery availability.
What are your site requirements for delivery? Get specific clearance requirements, ground condition needs, and slope limitations.
Do you conduct site assessments? Quality providers evaluate sites before delivery to identify potential placement problems.
What happens if delivery can’t be completed due to site conditions? Understand policies about refused deliveries, return charges, and rescheduling fees.
How much notice do you need for delivery? Lead times vary by provider and season. Busy construction seasons may require advance scheduling.
Rental terms and costs
What’s included in the rental rate? Clarify whether delivery, pickup, and any other fees are included or separate.
What’s the minimum rental period? Some providers require minimum commitments. Understand terms for short-term vs. long-term rentals.
How does pricing change for extended rentals? Monthly rates may decrease for longer commitments.
What’s your damage policy? Understand your responsibility for damage beyond normal wear. Ask about security deposit requirements.
What are your pickup requirements and fees? Confirm advance notice requirements and any charges for early or extended pickup.
Service and support
What areas do you service? Confirm they serve your project location and understand any distance-based fees.
How quickly can you respond to service needs? Ask about container swaps, relocations, or emergency pickup timing.
Who do I contact for service issues? Understand whether you’ll work with local teams or centralized customer service.
Can you provide references from similar projects? Quality providers can connect you with customers handling similar applications.
Key Takeaways
Portable storage containers provide secure, weather-resistant jobsite storage in standardized sizes, with 20-foot and 40-foot containers being most common. Container condition ranges from new one-trip units to cargo worthy, wind and watertight, and as-is options, each offering different balances of cost and condition.
Cargo worthy certification indicates containers meet international shipping standards for structural integrity and weatherproofing, though wind and watertight containers often serve storage needs equally well at lower cost. Properly maintained containers in good condition effectively protect contents from weather through steel construction, raised floors, door seals, and welded seams.
Delivery requires adequate access clearance (60-120 feet for roll-off delivery depending on container size), firm ground conditions, and overhead clearance for power lines and obstacles. Sites without standard access may use crane delivery at additional cost.
Common jobsite applications include tool and equipment storage, material protection, secure document storage, temporary offices, and seasonal equipment storage. Containers provide better security and weather protection than many alternatives, though specific needs may favor job trailers, storage pods, or other options depending on mobility, climate control, or customization requirements.
Selecting containers involves evaluating condition needs, delivery requirements, rental terms, and provider service quality to match your specific storage requirements and site constraints.