How Geodesic Domes Work

In 1926, the world's first geodesic dome opened in Jena, Germany, as a planetarium funded by legendary optics manufacturer Zeiss. It features an exterior diameter of 82 feet (25 meters) and is the oldest planetarium on Earth.

The planetarium's construction was the brainchild of Zeiss engineer Walter Bauersfeld, who realized that the building had to be extremely lightweight -- as it was to be placed on the roof of a Zeiss factory -- yet big enough to accommodate a large audience, strong enough to withstand storms and rounded enough to feature a nice projection surface for the planetarium's stars and planets.

To those ends, Bauersfeld decided on a geodesic design. In terms of their interior space, geodesic domes enclose the largest volume of space using the least amount of construction material. In turn, because they require so little with regards to material, they're also extremely lightweight. Finally, the geometric dimensions of the domes also lend them great strength.

The novel Jena building sparked worldwide interest in planetarium construction, and domes became more common. But in the 1950s United States, only a guy nicknamed Bucky could've popularized something as futuristic as geodesic domes.

"Bucky" was Buckminster Fuller, an American engineer who helped spread and commercialize polyhedral constructions throughout the country. It was Fuller who stuck these buildings with the term "geodesic," and he was awarded a U.S. patent for his dome in 1954, even though Bauersfeld unveiled his designs decades earlier.

Fuller took his dome design inspiration from nature. He marveled at the structural uniformity of things like snowflakes, seed pods, flowers and crystals and resolved that humans should emulate those simple, strong, and noticeably spherical arrangements [source: The Futurist]. Thus, he began working in earnest on geodesic domes, which he saw as an economical, efficient way to address the post-World War II housing shortage.

He began construction on his first dome in 1948. That dome immediately failed due to the weak and thin Venetian-blind slats he used. Subsequent (and much more successful) models featured strong, lightweight materials such as aluminum aircraft tubing.

They worked in part thanks to a structural principle that Fuller coined – tensegrity. Tensegrity is a word made of two others -- tensional and integrity -- and refers to to the relationship and balance between tension (tightness or tautness) and compression (a force shortens or squeezes something) in a structure. Although these structures had relatively little mass, their shape allowed them substantial rigidity that supported great weight.

The low quantity of materials necessary for geodesic domes, matched with their durability and good looks, means they've found their way into places all over the world. In Antarctica they've stood for decades and resisted winds of around 200 miles per hour (322 kilometers per hour). Domes have also withstood hurricanes, earthquakes, and fires better than rectangle-based structures.

They've been used for military radar systems, churches, auditoriums and also for all sorts of special events in which temporary, inexpensive and strong shelters are needed. On the next page you'll see why the special construction of these domes makes them so useful.

People have been building domes for centuries. Ancient peoples such as the Romans applied their masonry skills -- and their knowledge of the arch -- to create massive domes. But those domes needed equally large supporting walls keep the entire structure from crashing to the ground. In short, huge old domes were heavy and bound to fail at some point.

Geodesic domes are different. Not only do they incorporate the strength of a strong arch shape, but they're also made up of many triangles. Pair domes with triangles, and you have one extremely durable structure. Triangles are the strongest shape because they have fixed angles.

Much of that durability results from the characteristics of triangles, which are the superheroes of shapes. Triangles are the strongest shape because they have fixed angles and don’t distort very easily.

Michael Busnick, owner of American Ingenuity, which sells dome homes, says triangles are key to making domes strong. “(Domes) are three-dimensional structures using stable triangles approximating spheres to create multiple load carrying paths from point of load to point of support. The triangle is the only arrangement of structural members that is stable within itself without requiring additional connections at the intersection points to prevent warping of the geometry.”

In other words, apply pressure to one edge of a triangle, and that force is evenly distributed to the other two sides, which then transmit pressure to adjacent triangles. That cascading distribution of pressure is how geodesic domes efficiently distribute stress along the entire structure, much like the shell of an egg.

The pattern of those triangles is critical to the structure of geodesic domes. To understand why, consider first a basic four-sided square. If you lay many squares perpendicular (at right angles) to each other, they can lay neatly into a flat plane.

The same isn't true of pentagons or hexagons. Try to lay these shapes flat in the same manner as the square and it won't work. But tilt these shapes inward into a ball or sphere shape and the sides match up nicely as tessellations, which are simply patterns that can be repeated to create another shape without overlapping or spaces between the shapes. And it just so happens that pentagons and hexagons can be neatly divided into triangles, the foundation of geodesic domes, so they're also exceedingly strong.

Different tessellations result in varying designs for dome buildings. On the next page, you’ll read more about how designs make it easier -- or much harder -- to assemble domes.

Not all geodesic domes are alike. The most basic and common dome is based on the aforementioned icosahedron with its 20 faces made up of equilateral triangles. You can make ever larger domes by dividing the face of each triangle into smaller and smaller triangles.

As you view a geodesic dome, you may notice that the lengths of support struts (the individual rods or bars) making up the dome's frame usually aren't identical. In the most basic kind of dome design, there are many different lengths of struts necessary to complete an unbroken sphere.

A one-frequency dome employs struts of one similar length. Likewise, a two-frequency dome uses two distinct strut lengths. Lower frequency domes (those with fewer parts) are easier to put together, but those with greater frequency can be built to bigger sizes. When assembled into triangles, struts are called trusses. The joint where the straight ends of the struts meet is called a node.

Struts must be measured and cut precisely in order for the dome to take proper shape. So for anyone who has to deal with the challenges of the dome's actual physical construction, fewer lines make for fewer struts and much easier assembly.

So although software might be able to calculate enormously intricate domes, in reality, only a few basic designs usually wind up in the real world. More complex plans – that is, those with great frequency -- require struts of many varying lengths, and as such they are more difficult to put together.

Once a dome design is ready to go, builders select the desired materials. Dome struts may be high-strength metal alloys, or more traditional wood members. The nodes, or hubs, that connect struts are often steel.

After the framework is complete, it must be covered. The triangle panels are generally made of plywood, plastics or concrete. The interior of the dome is often lined with insulation and finished with triangular sections of drywall or wood.

With a smart dome plan, there’s no limit as to how high those triangles will go. Keep reading to find out more about how domes are built and how Fuller’s geodesic creations took on gigantic proportions -- and then went up in flames.

Logical, thoroughly planned domes can accomplish feats that other construction techniques cannot. As evidence, there’s the mammoth dome that helped hurtle geodesic domes to celebrity status.

In 1953, the Ford Motor Company hired Bucky Fuller to create a dome that would enclose a central courtyard at the company’s headquarters. The gap over the courtyard was 93 feet (28 meters) across, and traditional building techniques would make a gigantically heavy dome that would crush its supporting walls.

Enter Fuller and his geodesic designs. He convinced the Fords that his plan would weigh less than 10 tons (9 metric tons) and cost much less than an old-fashioned dome. Within months, Fuller had disproved all of his doubters by finishing the project ahead of schedule, covering the opening above the courtyard as planned. Engineers around the world were amazed, and Fuller became famed for his expertise.

A few years later, a leak was spotted in the dome, and a team was sent to fix it. Unfortunately, they accidentally set the dome on fire and it was destroyed. No matter -- Fuller’s idea had already taken hold.

He was later hired to create what would become one of his most famous domes, this time for the 1967 International and Universal Exposition in Montreal. This 250-foot (76-meter) dome was nearly 200 feet (62 meters) tall and served as an architectural centerpiece to the fair.

Fuller liked to think big. After his success at Ford, he even speculated that a huge dome could cover part of Manhattan Island. The dome would moderate temperatures, and equipped with air filters, could keep people healthier by lowering germ and virus counts. What’s more, Fuller thought the dome would pay for itself by eliminating the cost of snow removal. His audacious idea never quite caught on, though.

Not all domes are built with immensity or grandeur in mind. Some are very practical. On the next page, you’ll read all about how some imaginative homeowners trade blocky, rectangular houses for domes, sweet domes, as homes.

In the 1960s and 1970s, counterculture was all the rage, and newfangled geodesic domes fit that anti-mainstream vibe. Many people viewed strong, eco-friendly, inexpensive domes as the homes of the future, and they were ready to ditch traditional right-angled, squared construction for triangle-based houses.

The benefits seemed obvious. Spheres enclose a maximum of space with a minimum of materials, and they don't require interior supports. Their aesthetic appeal for many people is undeniable; the high ceilings and open feeling can make them attractive, and it's easy to build lofts inside for partial second-floor space.

The spherical design results in highly efficient and effective air circulation in both summer and winter. Less surface area makes these buildings less susceptible to temperature changes, and thus, inexpensive to heat and cool as compared to rectangular homes. The aerodynamic exterior means cold and warm air flows around the structure instead of forcing its way into the interior.

They are so easy to assemble from kits that do-it-yourself types without construction experience can assemble color-coded kits in just a day or two with the help of friends. These kits may include wooden struts or metal alloy parts, but either way, the components are lightweight and don't require cranes or other high-powered equipment.

Yet some of the advantages of dome homes also translate into disadvantages. The same shape that makes for efficient airflow means sounds and smell travel throughout the home, too, meaning there's very little privacy and a lot of potential for annoying, amplified echoes. Similarly, light bounces around domes, meaning a single small light can wake up everyone in the house.

Interior curved walls are major challenges when it comes to construction contractors. Everything from insulation, to plumbing, and electrical conduits must be carefully reconsidered in a round home, and because standard construction materials are made for rectangular homes, dome components are generally more expensive. What's more, some contractors refuse to even work on domes because the frustrations and costs are too high, and profits too low.

Even furnishings can be problematic. Couches, tables and beds are all made to sit flush against flat walls. Put them in a sphere and not only do they look out of place, but they also waste much of the wonderful extra space that spheres impart.

Waterproofing is another hurdle. Flat roofs are easy to shingle so that they shed rain. But the many triangles and seams in a dome home are another matter altogether. Water intrusion has spelled the end of many a rounded home.

These days, dome kits are still popular with hobbyists and the sustainability-minded. Many companies, such as American Ingenuity, Pacific Domes, Timberline Geodesic Domes, Oregon Domes and Natural Spaces Domes all sell dome homes and plans. The complications and drawbacks of domes, however, may prevent them from reaching the kind of popularity of years past.

There's no sure count of how many geodesic domes exist in the world, but the big ones are easy to spot.

The world's largest dome resides in Fukuoka, Japan and is aptly named the Fukuoka Dome. This huge dome serves primarily as a baseball stadium and seats more than 30,000 people.

It also has a unique retractable roof. The roof comprises three steel-framed titanium panels that have a surface area of around 59,795 square yards (50,000 square meters). Altogether, the struts and panels of the roof weigh about 12,000 tons (10,886 metric tons) [source: Web Japan], yet it takes only about 20 minutes for the panels to retract, exposing spectators to the skies above the city.

Tacoma, Wash., is home to the world's largest wooden dome: the Tacoma Dome. This structure has enough room to seat more than 17,000 fans for basketball games, thanks to its 530-foot (160-meter) diameter and 152-foot (46-meter) height. Although the arena was primarily constructed as a home for the former professional Seattle Supersonics basketball club, it's big enough to be used for the 100-yard long fields of football games, although this significantly reduces seating capacity [source: Tacoma Dome].

The Eden Project, located in Cornwall in the United Kingdom, is another dome masterpiece. The project includes two huge domes that are climate controlled to emulate different regions from around the world. One dome, for example, encloses a very warm and humid tropical environment that keeps the equatorial plants inside flourishing.

The tropical dome (called the Tropical Biome) covers nearly 4 acres and uses a steel frame to reach a height of 180 feet (55 meters) and width of 328 feet (100 meters). The adjacent Mediterranean Biome is comparatively small, at 115 feet (35 meters) high and 213 feet (65 meters) wide. Because the plants below need ample sunlight, a thin, transparent plastic film that's durable enough to withstand local weather [source: Eden Project].

One of the most iconic geodesic dome designs in the world is actually a complete sphere. It’s Spaceship Earth, an 180-foot (54.9-meter) tall, silver geosphere at the center of Epcot theme park, which is part of the Walt Disney World Resort in Orlando, Fla. Epcot is an acronym for Experimental Prototype Community of Tomorrow, which was Walt Disney’s idea for an experimental, utopian community.

Unlike most domes, this one doesn't even try to repel the rain with any sort of shingles or panels. Instead, the panels are arranged with 1-inch gaps between them. Water flows into these spaces and to the bottom of the building, where it's used in one of the park's lagoons.

There's a ride inside the sphere that's also called Spaceship Earth. Riders move briskly through scenes of humankind's development, from prehistoric cave dwellers to a modern, technology-driven society. For that reason, maybe the Epcot sphere is a good symbol for geodesic domes as a whole.

These rounded structures represent our capacity for imaginative thinking and building, as well as our ability to create concrete, useful items from abstract ideas and theories. Although geodesic domes may never be as popular as Bucky Fuller and his acolytes hoped, these half-spheres are a testament to the inventiveness and persistence of people everywhere.