Orion Style Monolithic Domes
An Orion-style dome uses spray-in-place, single-sided form technology to create a stemwall for a Monolithic Dome—a Monolithic Dome with a vertical wall around the base.
The idea for using a single-sided form to create the stemwall for a Monolithic Dome was hashed out between David B. South and Dave South at a Taco Bueno in Waxahachie, Texas, in 1999. Prior to this, stemwalls were built using concrete blocks and other more expensive methods.
In 2000, Monolithic built the first dome using an Orion stemwall for Gary Clark, VP of Monolithic, and his family at the Monolithic Dome Research and Industrial Park. They named it The Orion, and the spray-in-place method of constructing stemwalls was given the same name.
Watch this video for an in-depth look at the construction process of an Orion-style dome.
In 2001, the first Monolithic Dome gymnasium with an Orion-style stemwall was constructed for Italy High School in Italy, Texas. The plan called for a curvilinear stemwall, and the resulting facility was a show-stopper. The next year, a neighboring school district, Avalon ISD in Avalon, Texas, built its Monolithic Dome gymnasium the same way.
The Orion-Style Monolithic Dome Construction Method
At the start of construction, wood forms, shotcrete and rebar are used to create a curvilinear or segmented reinforced concrete wall, upon which an Airform membrane is attached to the top. Next, the entire structure is pressurized—inflating the membrane.
Once the Airform is fully inflated atop the semi-structural wall, construction proceeds exactly as it would on a true dome, or a dome constructed from an Airform only. Crews enter the pressurized dome through an airlock, and the next phase begins.
Once inside, several inches of polyurethane foam are applied to the interior of the Orion wall and Airform membrane, sealing them together as one piece. Next, a grid of steel rebar is attached to the foam—from the foundation to the apex of the dome. Finally, shotcrete is applied inside the entire wall/dome structure.
When finished, the foam and reinforced concrete, from floor to ceiling, form a seamless, one-piece, monolithic Monolithic Dome with a stemwall.
After all the concrete has cured, the exterior wooden forms are removed from the stemwall, revealing the outer reinforced concrete wall. This wall can be painted, plastered, brick veneered, or covered with siding.
Above the stemwall, the Airform stays in place as the single-ply roofing membrane over the dome that will require coating every 5-15 years (depending on UV and weather intensity) to maintain its integrity. Some owners choose to have a more permanent exterior coating of stucco applied at the time of construction over the Airform (which will also need to be coated every so often), but most simply maintain their domes with regular cleaning and coating.
Staying Strong (and energy efficient)
Using Orion-style stemwalls keeps costs low and gives homeowners, schools and communities the vertical walls they desire, without sacrificing the disaster resistance and energy efficiency inherent to the Monolithic Dome. It’s important to note that Orion-style Monolithic Domes are often constructed with grants from FEMA and other disaster-mitigation programs because they double as disaster shelters and can protect community members during tornadoes, hurricanes, earthquakes and fires.