After buying a shipping container online, you’ll go through a series of expected events – have it scheduled for delivery, and have it arrive via either a tilt-bed or flat-bed truck to your desired destination. There is one aspect of delivery that people don’t often consider though: where to place their container, and if the foundation is sufficient.
If you’re only using a shipping container for a brief period of time, you can leave it where it’s offloaded. For instance, if you’re buying shipping containers to pack up your house’s belongings and then transporting them to your new house within the span of a weekend. As long as the surface is flat, level, and solid, the shipping container’s temporary resting spot should be fine.
However, if you’re hoping to keep your shipping container in the same location for a matter of weeks, months, or even years, then placing your shipping container on a proper foundation is essential.
Read ahead to find out why foundations are an essential consideration for shipping container placement and what types of foundations are most ideal for shipping container placement.
First and foremost, a foundation prevents a shipping container from sinking deeper into the earth. After all, a shipping container is very heavy. An empty 20ft shipping container weighs 5,181 lbs, while an empty 40ft shipping container weighs 8,267 lbs. As expected, that weight only increases the moment that you add cargo or other materials inside. For example, if you converted your shipping container into a pool and filled it with water, it could hold over 5,000 gallons of water inside of it — that’s over 41,000 lbs.
Many don’t consider that the ground may not be able to support the weight of the shipping container. Unless the ground is rock-solid, the bottom of your container could sink over time. Your area’s soil type can exacerbate this problem. For example, some areas of the country have soil with a lot of clay in it. Clay is wet and soft. It also swells and contracts with changes in temperature and precipitation, which can pull the bottom of the container down. Before placing your container on the ground, be sure to assess what type of soil your land is made up of.
It’s important to keep your shipping container perfectly level so the container’s structural elements don’t shift and warp over time. To achieve this, choosing the right foundation plays a huge role.
Shifting and warping will cause serious structural problems. If the main door’s frame shifts, it will be difficult to open and close the doors properly. The floor, walls, and roof could become uneven. If shipping containers have been converted into a multi-level house, shifting can cause the separate levels to become uneven. Any windows and doors installed in the building might not open and close properly. In worst case scenario, your container home could lose structural stability and require intensive renovations to restore its integrity.
A proper foundation can also minimize corrosion on the base of the shipping container. How? Certain types of foundations will raise the bottom of your container off the ground, which prevents groundwater from touching the bottom and creating rust. Other types of foundations can create a thick barrier between the shipping container and the ground, which should prevent groundwater from touching the base of the container.
Corrosion can affect the durability of your shipping container, and severe corrosion makes it easier for your container walls to take on damage and spring leaks.
The answer to this question is that it depends on how long you expect to keep your shipping container in that location. If you’re keeping your shipping container in a single spot for several weeks, you can use a short-term solution. If you’re planning on keeping your shipping container in that location permanently, you will need a long-term one.
You’ll also need to consider factors like your area’s soil type, the local climate, and your budget. Talk to a professional contractor or structural engineer to get a better idea about which foundation is right for your shipping container plans.
If your shipping container is not going to stay in the location forever and in a matter of weeks or months, you’re going to move it, you’ll want to look into a temporary foundation.
One of the temporary foundations for shipping containers is called blocking. Blocking is when you prop your shipping container on top of a foundation of concrete blocks. The weight of the shipping container should keep the concrete foundation blocks firmly in place. Try not to stack too many concrete blocks on top of each other. The higher you stack your foundation blocks beneath your shipping container, the less sturdy the foundation will be.
Another solution you could try is resting your shipping container on a series of railroad ties. Railroad ties are rectangular pieces of wood used to support the rails along railway tracks and are used to keep shipping containers off of the ground.
Cement blocks and railroad ties will raise your shipping container off the ground, which will prevent water from pooling around the bottom and causing corrosion. The foundation styles can also make moving your shipping container a little easier when you no longer need it to be in that location. The materials aren’t attached to the container, so the container can be picked up with a forklift or crane without difficulty.
If your shipping container is going to stay in the same spot long term, you’ll want to rest it on a foundation that will keep it level and away from groundwater permanently.
Long-term foundation options are especially important when you’re building a shipping container house. You should never use a short-term foundation option on a shipping container house. A short-term foundation can’t offer long-term support, and when used longer than intended, can result in shipping container damage that could prove costly. You might also find that your local zoning regulations only allow shipping container houses that are on permanent foundations. Houses without these foundations will be considered zoning violations.
A concrete slab foundation is a thick barrier between the bottom of your shipping container and the ground, which can protect it from corrosion, water intrusion, and pest infestation. This will be one of the more expensive foundation options for a shipping container.
Another long-term solution is a concrete strip foundation (also known as a trench foundation). It is made of a series of sunken concrete walls instead of one full slab. One of the biggest advantages of this foundation style for shipping container homes is that it leaves room for utility lines and plumbing to go beneath the house.
A pile foundation is made up of solid steel piles (cylindrical tubes) that are driven deep into the ground and capped with concrete. It is an ideal foundation style for shipping container homes in regions with softer soil.
A pier foundation is a very popular foundation for shipping container homes and other permanent structures. It is very similar to a pile foundation. Cylindrical concrete piers (often reinforced with steel) are placed into the ground until they rest on compact soil. Each pier supports a shipping container corner, and sometimes its middle points for stronger weight distribution.
Don’t risk cutting corners when choosing a foundation for your shipping container. By following the steps outlined, you can ensure that your container has a solid foundation that is level, removed from groundwater, and properly anchored. Taking the time to plan and execute a proper foundation will increase the lifespan of your shipping container, whether you are using it for storage, as a home, or for any other purpose.
Short term rentals and accessory dwelling units (ADUs) continue to grow in popularity along with the options for providing such services. Pairing the growth of the custom shipping container industry with these options can provide you a comfortably inhabitable home, customized to your liking, in a much quicker turnaround time. So then the next question pops up once you have realized shipping containers as a possible option for you. How do you prepare for your new shipping container home? With this blog, we will walk you through the process and possibilities in permitting and land preparation. If this leaves you with more questions than answers, give one of our container techs a call today to discuss your potential build(s).
There are many ways to go about getting permitted, but the most efficient process can vary. Most U.S. states accommodate prefabricated metal structures, but local town and county permitting codes can obstruct the process. In some places, it is possible to build a container without a permit. However, you should be aware and acknowledge potential regulations, permits, or zoning issues that could hinder the experience or build process.
When asking questions to local authorities and building inspectors regarding permitting, codes, and zoning, you should know a few different ways to increase the chance of approval.
The last thing you want to do is ignore the fact that permits, codes, and zoning exist. This can result in fines, penalties, or even worse, remove your container home. Most areas continue to welcome containers, and there are very few exceptions where containers are explicitly banned. It is important to remember that no city or state will outright say “no container homes” because the meaning of ‘container home’ is so broad. Oftentimes a rules official will say “no” just because the proposition is out of the ordinary and they don’t want to face repercussions. This is why you approach permitting, code enforcement, and zoning very carefully and make sure your proposal is concise about your specifications.
You can make your container home classify as an RV by adding caster or dolly wheels if you choose. Adding caster or dolly wheels to your prefabricated metal structure is a great way to bypass the idea or label of housing a permanent structure on your property.
Much like any home, container homes need level ground for placement. Before starting the build process, you must be certain the area your container will live in is easily accessible by a delivery truck. It is essential to leave ample room around the container for easy accessibility to adjust the container, bring in furniture, etc. Container homes, much like any home, must be level to operate normally. If your container home is not level it can result in slanting that allows for doors and/or windows to not shut properly. The ground moves a considerable amount and can cause your container to move, sink, or slide if it’s not leveled properly.
In addition to generic leveling, we recommend your container home be raised off the ground. Lifting container homes off the ground will prevent water intrusion and rust to ultimately extend the longevity of your home.
Container homes can very well be dropped on level ground that’s not raised, but a foundation of some sort is highly recommended. Building a foundation for your container home is the best way to keep unwanted pests and elements out.
Container home foundation options we recommend:
Concrete slab foundations make the best foundation for container homes. This is the most expensive option, but if you are looking to keep your home in the same location long-term it is a viable option. The concrete slab should be four inches deep, and must extend an extra two feet wide on each side of the container so the home fits comfortably.
Pier foundations are another popular option for container home foundations due to the price, quick build time, and it is DIY-friendly. Pier foundations are typically designed with concrete blocks or footings and are a great option if you plan to relocate your container home in the future. This foundation allows the container to be moved easily from place to place since no foundation is directly attached to the container. When setting up your pier foundation, one concrete pier should be placed at each corner of the container. However, on 40-foot containers, you should add two additional piers in the front-middle and back for extra support.
Gravel pads are another trusted option for foundations. This foundation is made with a type of gravel and calcium carbonate that acts as a natural cement. The foundation is rolled, compacted, and spread onto a level surface that typically raises 4 to 6 inches off the ground. Similar to a concrete slab foundation, you should allocate at least one extra foot of space for ample room to move around the container.
Railroad ties are a cheap, viable option for container home foundations. If chosen, railroad ties should be placed at each end to elevate the container, and one in the middle for extra support. Railroad ties, treated 4×4 wooden beams, and other similar skids are a great option if the container will be moved in the future. These options can be used as permanent foundations, but if you plan on living in the container long-term it’s better to go with a more reliable foundation.
Connecting a container home from Bob’s is simple and hassle free. In fact, it’s practically the same as connecting an RV. This standard hookup option is for those wanting access to municipal water, electric and plumbing.
Off-grid options are available as well for those who do not have or want access to municipal services.
Container plumbing is essential, and nearly the same as residential plumbing. Plumbing hook-ups for containers require a 3-inch pipe for blackwater, a 1.5-inch pipe for greywater, and a .5-inch pex for freshwater. For those who do not know, blackwater is for sewage, greywater is for sinks and tubs, and freshwater brings in clean water.
Off-grid plumbing options consist of:
A tank or septic field is required for both blackwater and greywater if you choose off-grid plumbing. If you choose to go with water tanks, both tanks should be located above ground or buried near the container for easy access. Depending on how often the container is used, it is recommended you pump the tanks biweekly to maintain a clean living environment. If you choose to construct a septic field, site preparation must be carried out well before the container home arrives to avoid outrageous costs associated with a late setup. The septic field consists of two components, a septic tank, and a soil absorption field. Primary treatment will begin in the septic tank then, leftover water will infiltrate into the soil.
When it comes to off-grid water, there are a few options to choose from:
Gravity-fed water systems allow water stored in a tank to flow by its weight inside the pipes and run out of the tap. This system only works if the unit is located below the water’s starting level. Gravity will take control of the water if it is below the starting water level and will then flow out of the tap.
Another viable option for freshwater intake is a cistern watering system. This system stores water needed for household use in a large container that can be filled with collected rainwater, or by a water truck. Cistern watering systems are a great option for those who are outside the municipal water service or don’t collect much rainfall.
Freshwater tanks are also a great option. These tanks are typically made out of seamless polyethylene plastic and hold water for your sinks, toilets, etc. These tanks range from holding 1 gallon to 202 gallons of freshwater for your container home. Freshwater tanks are intended for homeowners who will not have access to water connections and/or sewage services.
In addition to off-grid freshwater practices, french drains are often used to recycle greywater which doubles as irrigation. Greywater will run its course through the drain line and end at the french drain where it will then disperse to irrigation.
Off-grid power options consist of:
Bob’s Containers has a solar package designed for website models, but if you are interested in another package you will need to calculate how big of a system your structure requires. Bob’s typically recommends a 400-watt solar package for 20-foot containers and a 1000-watt package for 40-foot containers depending on how many appliances are installed.
To sum things up, choose a foundation for your container home and a plan for how utilities will be set up in the home. Those two essential things will naturally allow your container home to thrive in its environment and show off how beautiful container home living can be. After all, container homes are more than just a place to live, they are an art piece!