Building with Shipping Containers

Environmentally friendly steel boxes are project building blocks

Shipping containers are being used for so much more than the transport of materials and goods across the country or oceans. Depending on where you are located, you may have seen an increase in construction using shipping containers. From residences to retail, shipping containers have started a new trend in the field of construction.

Paul Galvin, chairman and CEO of New York City-based
SG Blocks Inc., says that while there are multiple reasons people are interested in building with shipping containers, the primary reasons revolve around form and function. “Some desire a new method and approach, some are design driven, some desire efficiencies in construction, while others desire sustainable building practices,” he says.

Ruben Escobar-Urrutia, LEED AP BD+C, Grupo ARKHOS, El Paso, Texas, says that since the trend of building with shipping containers started, architects saw the potential of integrating the readily available byproduct as a building material. “It made us think about what we can do with such a sturdy steel box,” he says. “And, there’s the more common need to build sustainably, with recycling the boxes as a way to help the environment.”

Tim Steele, founder of Tim Steele Design LLC, New York City, says people are interested in building with shipping containers because along with the sustainable aspect, they are attracted to repurposing something. Also, clients are able to visualize the building blocks as a house. “If you’re building a stick-built house and you’re hiring an architect to design it for you, you’re really starting from scratch,” he explains. “Everything’s going to be on a piece of paper and you’re going to start talking about a floor plan and then develop it from there. With shipping containers, you’re thinking in terms of volume.”

Cost of Construction

It’s easy to believe that building with shipping containers will be significantly cheaper than building a traditionally constructed home, but Steele says its not always as inexpensive as people hope. Escobar-Urrutia says project costs depend on the type of project and how much modification is performed on the shipping containers. “Also, it depends on how much of the project you can perform on a workshop instead on the worksite,” he adds. “But most of our projects have end up costing equal or less than with a conventional method.”

While building a shipping container home seems like a simple project, David Fenster, AIA, LEED AP, principal and founder of MODULUS: Architecture, San Jose, Calif., says it’s not as easy as just throwing up some drywall. “There’s a lot of costs that have to go into making it livable, much like if you build any house,” he says.

The cost for buying drywall for a container home is the same as buying drywall for a woodstud framed house, and you still have to buy lighting, mechanical, flooring, fixtures, appliances and all of the things that make a house livable. “Everything is still kind of the same in that regard,” Fenster says. “What you get out of a container is a really cool module that allows you to be able to start thinking a little bit more creatively.”

Where you save time and money on shipping container construction is on the exterior envelope, since it’s not necessary to do as much exterior framing. However, time has to be spent cutting openings into the containers. “Containers have limitations,” Steele says, “and you have to understand how containers are built. And, you have to understand that once you start cutting out some of the corrugation, to keep a robust structure, you have to compensate with other structural elements.”

“You need to be creative in your approach to turn a shipping container into something wonderful,” Fenster says. “The coolest thing about the shipping container is that it’s a box, and it’s the strongest box practically that’s ever been built–it can withstand a ton. But it’s a box, and it’s a steel box, and you have to figure out how to craft and mold and bend and cut it to turn it into something worth living in.”

Design Considerations

Understanding the dimensionality of shipping containers is key to designing with them. Containers come in standard sizes, the most common being 40 feet long by 8 feet wide and 8 1/2 feet tall. Twenty-foot-long containers, and high-cube containers, which provide 9 1/2 feet in height, are also available.

Starting with those measurements, Escobar-Urrutia says you can start adding on areas in 8-foot or 40-foot increments. “You could modify the length of the boxes, but that would be less cost effective,” he explains. “Once you set your mind on designing on an 8-foot grid, you are as free to design as with any other construction method.”

The size of the container provides an interesting design challenge, and it’s important to figure out how to pair the boxes beside each other or on top of one another, where the holes and openings should be, and how to take advantage of the light and mass of adjoining containers. The modularity of the containers is a benefit, Steele says, but you have to work with the 8-foot width, and design with it, or cut the walls open and pair two containers together to try and disguise it, all while creating a wider space.

Shipping containers give you a floor, walls and roof from which to build a project. “Structurally these boxes are very sturdy, and if you use the corners of the box structurally you can load almost anything on top of it,” says Escobar-Urrutia. “Cost wise, this is an effective way to start a project. With some minor modifications, you can stack the containers on other ways than one on top of the other sitting on its corners, so more elaborate or creative ways of stacking is possible, it’s almost like playing with Legos.”

Understanding the interior clear dimensions, flooring and structure of the containers, is also beneficial. “You really want to play off the corrugation and the things about containers that make them unique, much like any other kind of construction,” Fenster says. “I’m a big fan of if you’re going to use a shipping container, don’t hide the fact that you’re using a shipping container. Make that part of the expression of what you’re doing, or else you’d be better off using a different material.”

Because shipping containers are so narrow on the inside, Fenster recommends using a small profile on everything you use. From insulation to LED lights, it’s important to maximize everything used to make a comfortable interior environment in as small a profile as humanly possible.

Containers and Heat

Shipping containers are a metal box where heat travels from one part of the box to the others. If containers are exposed on the exterior, Escobar-Urrutia says you end up having huge thermal bridges, requiring interior walls to be thermally isolated to prevent a wall radiating heat towards the interior space.

Heat is a major consideration that can be solved in different ways, including interior and exterior ways to prevent heat from entering or leaving the building. “We use paint mixed with non-sphere ceramic aggregate to repel heat on the metallic surfaces of the containers,” Escobar-Urrutia says. “Sprayed polystyrene or mineral wood on the interior walls and ceilings, covered with sheet rock, or a wood or polymer siding on the exterior with insulation between the container wall and the siding. Shading the containers with other elements is a great way to prevent heat to enter the building. If the container is not exposed to the exterior, then it is just like any other metal structural building.”

Shipping containers perform similar to other metal buildings, experiencing some contraction and expansion. Escobar-Urrutia says construction elements are attached against a metal column of bean. “The container is a watertight box, but cutting or drilling is something you need to detail to prevent leaks,” he says.

Additionally, even though shipping containers are built with Corten steel, there is still the possibility of rust. To prevent rust, Escobar-Urrutia says they sandblast the whole box leaving the bare steel, and then apply anti-rust primer and paint the containers.

Sustainable Aspects

Shipping containers are readily available on many port cities throughout North America. And, Escobar-Urrutia says the accumulation of containers is only getting worse as China is not purchasing more goods than it is exporting, leaving empty containers sitting in ports.

According to David Cross, vice president of business development at SG Blocks, American Recycler says it takes approximately 8,000 kilowatts (kW) of energy to melt down and recycle 8,000 pounds of steel, the equivalent of one container. When SG Blocks modifies a container, Cross says his company uses roughly 1/20th or 400 kW of energy. Additionally, he notes there is a reduction in the carbon footprint of the construction process when using shipping containers compared to traditional building methods.

“If a new building would use a metallic structure for its walls, ceilings, slabs, and most of this steel could be replaced with a shipping container, you end up savings tons of CO2 by offsetting the production of new steel elements for the construction,” explains Escobar-Urrutia.

Constructing the Containers

When it comes to building with shipping containers, first and foremost, it’s necessary to be sure the desired site is reachable by truck and can handle the construction of the containers. “Several project intentions have being cancelled because there is no economically feasible way to get six or eight containers to the site and have enough space for the crane to lift them into place,” says Escobar-Urrutia. “Sometimes the roads that lead to the site aren’t wide enough for a semi-trailer to get to it.”

As soon as the containers arrive on-site, modifications not done in a factory can begin. Cutting, reinforcing, interior work such as sheetrock studs, electrical installations, etc., can take place if the container is still not in place. On tight properties, work on containers can take place in a factory outside the construction site and then be brought in when the builders are ready for them.

Shipping containers are durable, low maintenance, and allow for a faster construction time. Cross notes that while the building time frame varies from project to project, it is reasonable that a 30 percent reduction from construction to occupancy is possible. Steele says the largest house his firm has built to date was 1,500 square feet, and with the foundation laid, once the containers arrived on-site, the construction only took two months.

Escobar-Urrutia says there is always a solution for a project. “Containers can be arranged in a variety of ways, and interior space does not have to be cramped, narrow or feel overwhelmingly low,” he says. “But it is an architectural solution not made for everyone. Not all clients make innovation or sustainability their goal when asking the architect for a solution for their project, and if they have not visited a project built with shipping containers, it is difficult for them to visualize what can be accomplished.”