Today, shipping containers are transformed into everything from homes to computer storage units of servers, and everything in between, as containers become heavier and heavier. A dry 40-foot container weighs about 6,800 pounds, or about 21 pounds per square foot. After it is modified in a small commercial store, in the cabin or simply becomes a storage container or toolbox, the extra weight of frame materials, drywall, insulation, lighting, HVAC, plumbing, as well as furniture and fixtures and pounds per square foot can easily increase by eight or ten times!
Although this is not an astronomical number in terms of building loads, it is significant enough to be concerned about the proper design and site or foundation for the installation of your building. If the foundation or pad that you want to install does not fit, even an empty or lightly loaded container will collapse, making the floors uneven and worse, doors that are very difficult to open, close and lock. When the container (or any structure in this regard) is out of level, the condition will continue to deteriorate, since the additional dead loads (building weight) will be directed to a low point of the structure. If you are planning to build a container house for transportation in an area where building permits are required, rather than a fully designed foundation design, it should be part of your departure part. However, if you are installing a storage container or cabin or in a rural area where authorization is not required, make sure that you do the preparatory work before accepting the delivery of your container.
The simplest type of base or pad for your container would be a smooth spot, ideally excavated about 4 inches down to a flat, level surface, crushing crushed concrete and compacting to about two inches, and then spread some 21A crushed limestone on top and compact it to about two inches. Both of these products have a binder in them that will help the pad stay together, but still allows moisture to drain. This method will allow the container to move around with frost, but it will work well for storage containers and other uses where you will not have utility connections or the container is attached to other structures.
If you are going to live in a container, connect to it or connect it to another building, then you should consider installing the pier foundation. This is still a fairly simple project, and if all the necessary tools are available, you should do it in a couple of hours. Do not pin the pennies here, if you do not have a screw with holes for the holes, hand over one. A 12-inch bit will work, but I would recommend a 16-inch or 18-inch bit, if available. The less stable your soil is the larger diameter of your piers, if you have sandy soil, wet soil or it is filled in the past, then you should go to 18 "piers.
Let's start:
First, lay out and mark the four corners of your container, do not forget rules 3, 4, 5 to make sure that your layout is square.
You will want to install a pier every ten feet down on both sides of the container. This means that you will have ten berths for a 40-foot cargo container and six berths for a 20-foot container. Mark the location of each pier.
You want the container to remain in the middle of the pier, so theoretically half the circumference of the pier will be under the container and the other half outside the container.
Wrap your holes to the frost level in your area, you should get a nice smooth cylinder with a flat bottom. You should make sure that the concrete is delivered shortly after your drilled holes. If you try to wait for the night and it starts to rain, you will have a mess on your hands.
Fill the holes with concrete, making sure that you do not leave voids. It is a good idea to press a round concrete shape, such as the Sonotube, the same diameter as your hole onto the top 4-6 inches of your concrete and level the Sonotube shape.
It is VERY important, use short two-four to level the concrete level, the top of your piers should be flat, otherwise you will not get the necessary support.
Wait at least 24 hours (preferably more), then carefully install the container on top of your piers. You will most likely need gaskets, make sure you use cast or steel gaskets, soft wooden gaskets will not help you.
The steps we showed here may seem redundant, but this is much less than removing the container, moving it and the subsequent steps described here later. A good base will give you a solid base for your container to provide you with many years of service.
