When it comes to building a shipping container home, it is crucial to select the appropriate containers as they form the foundation of the structure, serving as walls, floors, ceilings, and overall structural support. While you might think that “containers are strong and interchangeable enough, and any will do,” choosing the quality and condition of the containers is crucial to avoid future issues.
Even if you have no budget constraints, it doesn’t make sense to pay more for something you don’t really need. For a specific size and type of container (whose options are important to understand), there can be significant differences in terms of aesthetics, performance, and cost. In this article, we will explore the advantages, disadvantages, and costs of some options available in the market. We will also address how containers are inspected while in service and then teach you how to perform your own inspection before purchasing them.
Why is the condition of the container being purchased important?
Before acquiring the containers, it is essential to know exactly what type of containers you are looking to buy. Buying the right container is important and is related to proper planning for the construction of the container home. The planning and design will determine the type of container needed (usually a general-purpose – GP – container or a dry van – DV – container) and its size (such as a standard 20 or 40-foot container or a taller one). We cover these considerations regarding container dimensions and recommend starting there if you are not yet familiar with the options. However, selecting the right container does not end there.
The second part of the decision involves determining in what condition you want or need the containers to be for the project. There is often a temptation to save money by opting for cheaper containers and sacrificing the required condition. However, this is not recommended. You may end up with structurally weak containers or ones that require extensive repairs before they can withstand the elements. Trying to address these situations later on can cause construction costs to spiral out of control.
The condition of the containers is determined through an inspection, whether formal or informal. There are various inspections that can be carried out throughout the lifespan of a container, including the inspection you can perform yourself when purchasing the containers.
Different types of professional container inspections
The container inspection process starts early and continues throughout the container’s lifespan. In fact, manufacturers subject their designs, facilities, and processes to inspections even before manufacturing a container.
Once the owner receives the container, continuous tests and inspections are carried out during transitions between carriers and terminals, changes in tenants, changes in ownership or modes of transportation, as well as other circumstances involving container custody.
One entity that plays a crucial role in this entire process is the International Convention for Safe Containers (CSC). In the early 1970s, the CSC determined that containers required a reasonable system of maintenance, repair, and inspection to ensure the safety of the public, onboard workers, and personnel on the ground.
You are probably more familiar with the CSC’s Combined Data Plates, which are located on the front of the containers and contain relevant information about the specifications and history of that particular container.
For containers in service, the CSC requires operators to use an Approved Continuous Examination Program (ACEP) or a Periodic Examination Scheme (PES) to ensure compliance with safety standards.
The PES involves inspections every 30 months, which are recorded on the Combined Data Plates. The ACEP requires inspections correlated with specific repair or custody changes, with a frequency at least equal to PES inspections.
The ACEP number is indicated on the Combined Data Plate or a nearby label and is correlated to an online database that records information about the operator, administrator, and other data.
The actual dates of ACEP-related inspections are not publicly recorded in the same way as the PES inspections that are displayed on the Combined Data Plates. These two programs assist owners in monitoring the condition and maintenance of their containers but do not establish specific inspection criteria or repair guidelines.
Instead, container owners self-regulate with the help of various industry groups that have established standards for inspection and repair. However, the requirements differ for containers owned by shipping lines compared to those that are only rented out.
As a result, there are several competing industry systems, such as:
- Unified Container Inspection and Repair Criteria (UCIRC): The International Chamber of Shipping (ICS) standard and the standard used by shipping lines.
- Common Interchange Criteria (CIC): A more conservative version of UCIRC used for containers that are moved between shipping lines and rental companies.
- Guide for Container Equipment Inspection, 6th edition of the Institute of International Container Lessors (IICL-6): A widely used standard by rental companies. The previous version, IICL-5, was an independent standard.
In addition to these inspection systems, there are classification societies, which are independent, non-governmental organizations responsible for auditing and inspecting various maritime equipment, including containers.
These inspection societies utilize the aforementioned inspection systems, among others, to certify a company’s containers. While there are about 50 classification societies worldwide, some of the most well-known ones include:
- American Bureau of Shipping (based in Houston, Texas, USA)
- Lloyd’s Register (based in London, England, UK)
- Bureau Veritas (based in Paris, France)
- Nippon Kaiji Kyokai (ClassNK) (based in Tokyo, Japan)
- DNV GL (based in Oslo, Norway)
In addition to classification societies, there are other inspection agencies and repair centers that are typically not required to be the inspection authority according to any formal legal standard. Regulations usually only require a competent person to conduct the necessary inspections.
The variety of inspection types and the groups that perform them can be confusing, and this is just the beginning. There are additional requirements and approvals for rail and road transportation, not to mention rules for transporting hazardous cargo or going through customs between countries. We won’t list the numerous regulatory agencies and inspections to avoid overwhelming you.
If this entire process seems overwhelming, don’t worry. You don’t need to understand the inspection criteria of these standards in detail or who creates or applies them. All the above information is provided for your general knowledge. When purchasing a container, one of these inspections may be mentioned as applicable, or you may even receive documentation related to the inspection. However, this usually applies to new, one-trip containers suitable for cargo, so you don’t need to worry too much about these standards unless you have plans to move your container home in the future.
Complying with a standard through inspection is a good sign, of course, but non-compliance is not necessarily cause for alarm. In summary, there are many parties involved in assessing the condition of containers, maintenance, determining when to retire them, and options available after their useful life.
Now that you understand the context of professional inspections, let’s discuss how to conduct your own personal inspection when considering the purchase of a new container.
When to Perform Container Inspections?
When embarking on a container home construction project, it is crucial that you take the time to conduct your own inspections of the containers. If you skip this step, issues may arise that will need to be addressed at some point and could result in expensive repairs in the future.
The inspections mentioned earlier are complex and detailed but are necessary due to the rigorous and challenging maritime journey that containers undergo. However, for a container-based residence, you can generally be slightly less strict in some requirements. Most inspections can be done visually, without the need for precise measurements or specific conditions for each specification.
Before we delve into the details of how to conduct the inspections, it’s important to mention the difference between pre-purchase inspections and post-purchase inspections. Depending on where you buy your containers, you may or may not have the opportunity to physically inspect them before delivery. It’s not that the inspection itself is different in both cases, but rather the timing and implications.
Guidelines for Pre-Purchase Inspections
When possible and feasible, it is recommended to conduct an inspection before purchasing the containers. If you are close enough to the container’s location, you can go in person and perform the inspection. If that’s not possible, an inspection via photos or videos may suffice.
If possible, provide specific instructions on what you want to be captured in the photos or videos (following our guide below). If you only receive existing photos or videos, they may not cover everything you need (and you’ll assume a bit more risk depending on the warranty provisions of the company you’re buying from).
Guidelines for Post-Purchase Inspections
A post-purchase inspection is typically conducted after the containers have been delivered to the construction site. Keep in mind that a successful inspection relies on someone being present to perform it. It is preferable to be on-site when your containers arrive or at least have a reliable and competent person who can receive and inspect them on your behalf. Depending on your agreement with the seller, you may have paid part or the full purchase price of the containers before their arrival.
You will likely have to sign an acceptance form from the company to officially take possession of the containers. Ideally, you should complete your inspection before this step, although you need to be prompt… Time is money, and drivers may not want to wait. Drivers probably won’t allow you to climb or enter the container while it’s loaded, so initially, you’ll need to conduct a superficial inspection until it is safely on the ground.
If you immediately notice something wrong with the container, talk to the driver and inform the seller immediately before it’s unloaded if possible. Each agreement with the seller is different, but the sooner you detect a problem, the better. If the seller has to send another driver at a later date to pick up the container, you are likely to encounter resistance and possibly an additional invoice.
How and What to Inspect?
Each container home construction is unique, and some people may work with lower-quality containers due to their projects, while others require higher quality. Although containers intended for maritime transport have stricter inspection standards, it is possible to deal with some imperfections if you plan to make cuts and modifications to the container. When designing your project, you can direct the layout in a way that damaged areas are cut for windows, doors, and larger rooms.
The recommended inspection methodology is relatively straightforward and does not require specialized equipment or technical knowledge. It mainly involves a detailed visual and functional inspection of all parts of the container.
By breaking down the container into its components, you can follow a procedure and ensure that no detail is overlooked. For the visual inspection, it is suggested to scan with your head and eyes in a direction perpendicular to the one you are walking. For example, when inspecting the floor, walk from front to back and scan from left to right. To inspect a wall, walk from front to back and scan from top to bottom. This technique ensures that every inch of the container is observed.
During the inspection, it may be helpful to have some tools on hand. A long selfie stick with a remote shutter button can allow you to take photos and videos in hard-to-reach or hazardous areas manually. A flashlight is necessary for inspecting the interior. A ladder or step stool can help visually check the top beams and ceiling. Additionally, you can use a hammer or other heavy metal object to assess the degree of rust present.
Main Structure
The strength of a container is primarily based on the 12 steel beams that make up the edges of each of its six faces. These beams vary in size and cross-section, depending on whether they are corner posts, bottom rails, or top rails. It is important to check if these beams are in good condition.
Most other parts of the container can be repaired relatively easily, but damage to the beams can be more complicated to resolve. It is crucial to keep in mind that many of these beams have a hollow cross-section and should be inspected internally and externally to assess their actual condition. While superficial rust is not a cause for concern, deeper rust and corrosion can significantly affect the strength of the beams.
Bottom
The bottom of the container is an area that most people do not see but should not be neglected. It consists of a series of small cross beams that extend across the width of the container and the two bottom rails. These beams are responsible for supporting the container’s plywood floor.
40-foot containers often have a gooseneck area at one end, designed to fit certain types of trailers and reduce the overall height during road transport. It is recommended to visually inspect the beams in this area, as well as any other part of the container. Due to its proximity to the ground and lack of exposure to the sun, it is common to find more rust in this area.
However, inspecting this area can be challenging as it is located beneath the container. Depending on the unloading method used, it may be helpful to take a look or take photos of the bottom of the container when it is halfway between the truck and the ground. Once on the ground, it will be difficult to see this area unless you have heavy equipment to lift the container. Be cautious and never place any part of your body under a suspended container. The use of a selfie stick can be helpful in this case.
Damage in the gooseneck area is not ideal but can be easily repaired if necessary. Since no one will see this repair, it just needs to be functional.
Walls
When it comes to the container walls, they make up the majority of what is visible and imagined when thinking of a container. They are made of corrugated steel, which contributes to the overall structure of the building and provides additional strength. It is normal to find superficial rust and dents on the walls of a used container as long as they are not too severe.
The difference between superficial rust and structural rust is easily distinguishable. If in doubt, you can use a hammer to tap on the area in question and look for large chips or changes in sound compared to an undamaged section. If you can see through the walls, it is a significant problem and likely indicates the presence of future leaks. A container with severe damage, as shown in the image, may not be worth repairing. However, if the planned cuts for doors, windows, and rooms align with the damaged areas, it may be advantageous to utilize a lower-quality container and avoid associated sacrifices.
Dents can also impact the design as they can affect the placement of other components of the building. For example, outward-projecting dents may prevent an adjacent container from fitting properly, and internal dents can affect the placement of interior walls. While it is possible to straighten out dents, the thickness and strength of the container wall material make the process more complicated than it may seem.
Roof
As for the container roof, it is made of corrugated metal with a slightly different shape than the walls. The best way to inspect it is by climbing onto the container roof, but if that is not possible, you can take photos with a selfie stick. When examining the roof, you should look for general conditions such as previous patches and signs of pooled water, which often correspond to dents. The hammer test can also help distinguish between superficial rust and deeper structural rust, but you should be cautious when distributing your body weight over the area in question. Internal inspection will reveal if the roof is watertight, so for now, it is important to focus on determining its structural condition. If you plan to build a secondary roof over the container, the condition of the existing roof may be less important. As always, it is crucial to consider how the container will be used and focus on the relevant areas for the specific construction project.
Final Doors
The final doors and their mechanical components are the only moving parts of the container. Because of this, they are more likely to accumulate dirt, rust, and corrosion. It is important to check the operation of the four locking bars, ensure that the handles and locks are properly adjusted, and verify that the doors open easily on their hinges. It is also recommended to examine the rubber seal around the perimeter of the doors for any missing pieces or signs of drying out or cracking, as this may indicate the need for replacement.
Interior
The internal inspection of the container is a continuation of the inspection performed on the exterior, allowing you to confirm the condition of the materials from the “other side.” It is important to check the walls, ceiling, doors, and structural elements from this perspective. Use a flashlight to get a good view. To assess the container’s watertightness, close the doors as tightly as possible from the inside and observe if any visible light enters. This test, known as the water tightness test, is preferably conducted during daylight and under clear sky conditions. If there is no visible daylight from the inside, it is unlikely that there are leaks. In the case of small leaks that cannot be detected by the light test, they can be quickly repaired with roof cement or a similar material.
Floor
The container floor requires special attention. The most common type of flooring is the original wooden plywood, although other types are available. In most cases, the floor is the only permeable material used throughout the container. This means that it is the only place where spilled chemicals may have penetrated to some extent into a porous surface. It is recommended to plan the internal inspection of the container after a period when the doors have been closed, as this will allow for a proper odor test. When you open the doors and enter the container, take several breaths. If you detect smells of mold or chemicals, there is likely a leak somewhere. It is also possible that the leak has been resolved, but the smell of mold persists. In this case, try to identify the problematic area on the floor that is causing the odor. It is important to remember that detecting a chemical smell does not necessarily mean it is toxic or harmful. Almost any substance can be harmful in high concentrations, so concentration is the most relevant aspect. The odor test is just a starting point and does not provide a definitive assessment of a problem as it is not quantitative in terms of concentration. However, if you have multiple containers to choose from, those with less odor are likely a better option. Regarding the physical condition of the floor, if you plan to reuse it as a finished floor or subfloor, check for large holes, missing parts, or significant cracks.
Documentation
There are different types of data and documents associated with an individual container, and understanding their significance can help reconstruct its history.
CSC Plate: The CSC plate, also known as the combined data plate, is the part of the container that contains the most information. It is a permanently affixed metal plate that provides relevant legal information. We will use the example of the CSC plate to explain some of the data found on it.
Container Identification Number or BIC Code: This number includes the owner prefix, equipment identifier, serial number, and a check digit. It is used to identify both the container and its owner. The check digit is used to ensure the accuracy of the container identification number.
Type Code: The type code consists of 4 digits and represents the type of container. There may be some additional manufacturer-specific numbers or letters. For example, the code “22G1” indicates a 20-foot general-purpose container with normal height.
Classification Society Approval: This data refers to the classification society that has approved the container. For example, “AB-447/02-06” means that the United States Transportation Office approved the container with approval number 447 in February 2006.
ACEP/PES: The plate may also include data such as the ACEP number or dates of inspections from the Periodic Examination Scheme (PES). This data provides information about inspections and certifications conducted on the container.
Databases for Knowing Which Containers to Purchase
There are several search tools provided by operators and owners that allow you to gather more information about available containers. Some examples include OEG Offshore, Seaco, and Hapag Lloyd.
The BoxTech database is another source of self-reported technical information on millions of containers in service.
Now that you understand what to look for when inspecting a container, it is important to review how the elements you (and other parties involved in the process) inspect translate into informal categories that describe the container’s conditions.
