There are various dehumidifying products on the market

Ahhhh fall, that time of year when people think about venting their container.  It's too hot, too humid, etc. It's the number 1 call I get this time of year for modifications.  I blogged about this back in May, 2013.  There are a few options to consider.

1. What are your concerns about the inside of your container? Containers are designed to transport goods across the globe in all kinds of weather, from hot, humid locations along the equator to freezing cold places like Alaska, or Minnesota, where we're located.  Most everything that you have in your home and office came to the store you bought it by way of a container.  They do a good job of keeping stuff the way it should be.  I find often that people worry that their container won't maintain a nice indoor atmosphere, but most things are OK in a container as is. But sometimes people are concerned due excessive humidity, heat an cold, or are storing things that produce fumes that need to be vented.

Fixed louvered vent

Fixed louvered vent

2. Are you worried about humidity?  If your main concern is humidity, a vent might not be the best option for you.  A container is designed with some small, passive vents that prevent pressure from building up in the container, but do not allow for much airflow.  As a result, when you close the doors of your container, it will stay the way you left it. That can be good or bad, depending on what kind of air you trapped in there. If you live in a high humidity area, the answer might be to not add a vent, but rather add dehumidifying products to suck the moisture out of the air.  By not adding a vent, you continuously pull and trap moisture out of the air and don't let new, humid air into the container.

There are a few products on the market that you can get at any hardware store that are cheap and easy to use. DampRid is one brand, but there are others out there.  The basic idea is the same. (We have used DampRid, only because that is what our local stores carry.)  They have pellets that pull moisture out of the air and trap it in a bucket, bag, etc., and depending on how humid your container is, you replace it every few weeks or months.  What I like about this option is that it might solve your problem without having to spend a lot of money or hurt your container.

Commercial-grade heating and cooling unit

Commercial-grade heating and cooling unit

3. Are you worried about heat and cold? If a temperature change is the issue, vents may or may not help.  For the cold, vents will only make things colder.  But for heat, sometimes some airflow in the container can lower the temperature in a container a bit.  It won't take a 100 degree container and make it something you want to cool off in, but the increase in air might help a bit.  To do this, louvered vents work well.  If you put one vent on one long side of the container by the doors and another one on the other side of the container on the other long side of the container by the other end of it, you will maximize the cross-breeze in the container.  This is the same idea as opening windows on opposite ends of your house to cool it down in the summer.

The other option is to add in an HVAC.  If you add an HVAC unit, you will probably want to insulate the container.  For more information on insulating containers, click here.  Containers are made of steel, so any heating and cooling will be lost quickly without insulation.

HVAC unit with cage

HVAC unit with cage

Conversely, I often get asked about insulating a container, but not putting an HVAC unit in it.  It doesn't work very well. It is like buying a cooler, putting your picnic in it without any ice or chillers, leaving it in a hot car all day and hoping for a cool meal.

4.  You are storing something that creates fumes.  This one is the most dangerous, obviously. The amount of air flow will really depend on what you are storing.  For some cases, the pair of louvered vents might work just fine.  But if it is something flammable or something where people will be spending a lot of time, you may need to consider a ventilation system.  It is best to find out from the manufacturer of the fumes what is the best way to handle that.

In addition to these ideas, there is always the whirlybird/turbine vent. I'll admit it. I just don't like them.  You're cutting a hole in the roof and putting a vent that pulls air down into the container.  So when it rains, it pulls the rain right down into the container.  It snows?  Same thing. It just seems like too much of an invitation for trouble.  I get some people just love this options, I simply am not one of them.

What are your concerns about venting containers?

AuthorSuper Cubes LLC

Edit: Please note that Super Cubes does not recommend burying containers without work with an engineer to ensure your container remains structurally sound when in place and complies with your local zoning.  Also, please test buried containers for radon.  Here’s your idea: Get a steel container and bury it as a root cellar, storm shelter, or both. You have the land. Now you need a plan. Here are the 5 things you need to consider to make your container cellar or shelter a reality:

1)       Zoning. Are there any state, county, or city zoning laws that would restrict where or how you bury a container?  This may vary depending on where you are, what the ground is like in your area, and how far into the ground you want to go. You can go the range from buried underground, nestled into a hill or embedding the container just far enough into the ground to be secure. Either way, zoning rules may apply. Start with a quick search of your city and county websites, then follow up with phone calls to offices listed on the sites. Take notes on the calls—and as decisions are made, “get it in writing” if you can.

2)      Placement. Is your plan to bury the container completely? Just far enough that a tornado won’t send it to Oz? In working out placement details, be sure to think through how you will use your container. If it will be a root cellar, will you build your container into a hill with steps and a door? If it will be an underground storm shelter, how will you provide access in and out? Keep in mind that the more deeply a container is buried, the greater the planning.

3)      Structure. If you will bury your container, even partially, how will you ensure that it withstands the pressure of earth? Containers were made not to be buried, but to be stacked on a ship. Only the four corner posts of a container are load bearing, with the sides strong enough to support only the roof. You’ll need to plan on building a retaining wall around the container location. Be sure to include drainage so that heavy rains won’t leave your container submerged in water. If your cellar or shelter calls for completely covering your container’s roof, you’ll also need to build a platform to push all the weight to the 4 corner posts (products are on the market to do this). Never simply bury a container or it will collapse.

4)      Moisture. Containers are wind and water tight, but think about how you will prep your buried container against earthen moisture. The container floor has treated plywood on steel cross-members. You will want to seal under the floor—and probably will want to set it on a cement slab foundation. In addition, you will need to seal your container with roofing tar, plastic tarps, or truck bedliners (such as RhinoLinings). A little research will help you find the most cost-effective solution for your container use and location.

5)      Ventilation. If you’re turning your container into a storm shelter, you’ll want to make sure it will have good ventilation and air flow for the people who will use it. You’ll also want to add an extra door—ideally a man-door with a panic bar so it can be opened safely from inside and so that no one can be accidentally locked in.

For an example of one being installed, see this video.  They approached some of the issues listed above a little differently, but it still provides some great ideas.  It appears that they put the container in an area with solid rock, so the rock walls provided the support that most people would have to build in place.

Once you have your container cellar or shelter in place, the rest is pretty easy—making sure your root cellar has the right humidity level for vegetables or that your shelter is outfitted to work well as a storm refuge. If you’re just beginning to start your cellar or shelter project, please keep in mind that SuperCubes offers a variety of kits to help you modify your container—and we’re always happy to provide friendly advice as well.