What does a LEED-certified Starbucks drive-through in Overland Park, KS, an office building in Providence, RI and a biomass conversion facility in Goodfield, IL all have in common? They were all built using repurposed cargo containers as their main building material. Yes those corrugated steel boxes you see stacked at shipyards, zipping past on a train when you’re stopped at railroad crossings or cruising beside you on the highway carrying goods from all over the world are finding a second life being recycled into all types of buildings. This building trend, coined cargotecture, has been used to build everything from restaurants and retail stores to single-family homes to dormitories and hotels.
Using cargo containers as building blocks is a great green solution for repurposing these giant steel boxes into something else once they’ve outlived their usefulness to ship goods across the world which is typically 10 to 15 years. When a cargo container reaches the end of its lifecycle it is no longer structurally sound enough to have up to seven other containers loaded with hundreds of thousands of pounds of cargo stacked on top of it but more than strong enough to serve as a building material. Because these containers are often made of Corten, a weathering steel alloy, it is costly to melt them down and recycle them into building materials like steel beams and columns. Some of the benefits cited for using include their strength, durability, mobility and affordability.
Strength & Durability
Cargo containers are constructed of steel and designed to carry loads upwards of 60,000 lbs. depending on their size and longer containers can weigh over 10,000 lbs. at their tare weight. Because of their rugged construction and structural strength they are virtually hurricane-proof and earthquake-proof. Because the Corten used to manufacture the cargo containers is a weathering steel it creates a regenerative protective layer when it oxidizes that prevents it from further corrosion to withstand the elements.
Because the containers are intended to be able to ship cargo virtually anywhere they can easily be transported by ship, truck or rail and are ideal for transport to any building site. When used as building blocks they are typically stacked and welded together. This means that the building can eventually be disassembled, relocated and erected again should the need arise. This is the case with the Keetwonen student housing city in Amsterdam that is scheduled to be relocated in 2016. New York City is pursuing cargo container apartments as a source of temporary housing for disaster relief with a prototype being developed for their Office of Emergency Management. Mobility is one of the key reasons cities like Oklahoma City, OK and High Point, NC are considering proposals that would set a collection of retails stores, restaurants and offices made of cargo containers on empty parking lots or undeveloped sites. The intention is to promote new business growth and revitalize prominent locations until more permanent solutions can be found.
Depending on location and availability, cargo containers can be purchased and delivered for a relatively low price. Keep in mind that all other construction costs associated with conventional construction will remain like electrical, interior finishes, plumbing, insulation, etc. This is in addition to the costs to stack, cut and weld together the reconfigured containers. If only a few containers are being used it might not be any more cost effective than a traditional building. I would imagine that the more containers used in a building would result in greater cost reductions due to price per container and overall labor costs. The Travelodge in Uxbridge, UK built in 2010 was constructed using 86 containers and boasted a 70 percent reduction in on-site waste, cost $750,000 less and was constructed 40 – 60 percent faster than a hotel of the same size using conventional building materials and methods. It should be noted that each container was up-fitted with all plumbing, electrical and bathroom fixtures at a factory in China before being shipped to the site in London to be configured and assembled into a hotel.
The argument has been made that using cargo containers as building blocks can’t be considered a green alternative. The claim is that the paint used to coat the containers often contains toxic chemicals to protect them from corrosion from the elements and that the wooden floors are treated with pesticides that often contain arsenic and that stripping them away creates a ton of hazardous waste. But wouldn’t removing and properly disposing of the hazardous waste to make a container habitable be more eco-friendly than allowing the container to the elements where that same hazardous waste will be created when the paint begins to flake and peel and the insecticide-treated wood floors begin to rot and decompose? It’s also been noted that the plywood floors in many cargo containers are made from tropical hardwoods that aren’t responsibly harvested in a sustainable way. This appears to be an issue to take up against the cargo container manufacturers since the intended purpose of the timber was flooring for a shipping container and not as a building material. The whole green aspect of cargotecture is reusing and recycling a component as a building material that otherwise would be discarded after its initial lifecycle.
Cargotecture has been proven as a versatile building material in everything from temporary disaster relief housing to upscale apartments and condominiums that can bring a green element to a construction project while also helping to reduce on-site waste, construction costs and building times. While cargo containers are not the ideal building material for every construction job or location, no building material is, they have been proven to be a unique alternative when they can be properly utilized.