Monolithic Domes
The Dome of a Home on a rare snowy winter night. Monolithic Domes are versatile, strong, safe, energy-efficient and save owners money. The feeling of serenity inside a dome is unmatched.
Monolithic Domes are thin-shell, insulated concrete structures used worldwide for homes, schools, safe rooms, gymnasiums, bulk storages, churches and more. They are constructed with polyurethane foam, steel rebar and concrete. Together, these materials create a disaster-resistant, energy-efficient and free-span structure. The cost of using these high-quality construction products is made affordable because of the dome shape’s efficient use of materials. A dome covers more area with fewer materials than any other comparable structure.
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The first Monolithic Dome was built 50 years ago. Thousands have been built across the globe. The technology is not new, it is proven. In a world with more natural disasters than ever, and rising costs for utilities, Monolithic Domes have a foothold in the mainstream. Not only are they the natural go-to building for schools with mandates to build tornando shelters disguised as gymnasiums or for towns who construct them as commumity centers that double as disater shelters, the Monolithic Dome is the choice for an increasing number of regular families who want to save money on ongoing maintenance and energy costs and gain the feeling of safety and serenity inherent in a Monolithic Dome home.
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Monolithic Domes have withstood major earthquakes, powerful tornadoes, raging fires, direct hits by hurricanes, and fiery explosions. Dome owners report energy savings greater than 50 percent over conventional structures. Also, it is often less expensive to build a Monolithic Dome School or Safe Room than it is to use conventional methods.
There are many beautiful Monolithic Domes. However, after 50 years, we believe architects and designers are just now beginning to understand the massive potential of the Monolithic Dome construction method to create free-form, natural and/or jaw-dropping architecture. The only barrier to great design is imagination. There is rarely a vision for a new project that can’t benefit by the incorporation of a Monolithic Dome. There are no columns or interior supports allowing complete design freedom. There are domes as small as 8-feet to over 340-feet diameter with engineering for even larger structures.
Construction Process
Monolithic Domes come in many shapes and sizes—multiple domes welded together, large domes on tall stem walls, small one-bedroom houses, giant auditoriums. All these share the same, basic construction process originally patented by the South brothers.
Step 1—Ring Beam
The first step is to create a ring beam of concrete and steel. It can be a simple, circular foundation, a slab on grade floor with an integrated ring, or a tall stem wall with the ring beam seamlessly integrated near the top. Vertical steel reinforcing bars, or rebar, are embedded in the ring beam to be attached later to the steel reinforcing of the dome itself.
Step 2—Airform Membrane
An airform—a tough, PVC coated fabric membrane—is manufactured to the proper size and shape. It is attached to the ring beam. Blower fans inflate the airform to create the shape of the structure to be completed. Fans run throughout construction. The airform membrane becomes the roofing membrane when the dome is finished.
Step 3—Polyurethane Foam
Closed-cell polyurethane foam is applied to the interior surface of the airform. Entrance into the air-structure is made through a double door airlock which helps maintain a constant interior air pressure. Foam is applied in layers with “rebar hangers” embedded in the foam. Typically the foam is around three inches thick but can vary depending on the application.
Step 4—Steel Reinforcing
Steel reinforcing rebar is attached to the interior, foamed surface via the embedded rebar hangers. The rebar is laid out in an engineered pattern of hoop (horizontal) and vertical steel bars. Small domes need small diameter bars with wide spacing. Large domes require larger bars with closer spacing. Double mats of rebar are often used for large, load-bearing storages.
Step V: Shotcrete
Shotcrete is a special, sprayable mix of concrete. It is applied to the interior surface of the Monolithic Dome—yes, it’s sprayed overhead in layers and not poured over the form. Small domes typically require three inches of shotcrete. Larger dome requirements vary depending on the size and loads, but ultimately a Monolithic Dome is a thin-shell concrete structure and the amounts are remarkably efficient. The blower fans are shut off after the concrete is set and the Monolithic Dome is complete.
Finished structure
The layers of Airform, foam, steel, and concrete form a one-piece—monolithic—insulated concrete thin-shell. The Airform is the roofing membrane, the foam is the insulation, and the steel and concrete is the structure.