Do you have to build a foundation on a monolithic dome house? Monolithic dome homes have to have a hard surface for the dome to sit on, but no strenght is rooted in a foundation. In a traditional house,...
In a traditional house, the purpose of the foundation is not only to keep the house from sitting on the ground, but also to bear the weight of the structure and hold the pieces together. Without a foundation of some sort, a traditional home would simply fall apart.
Building a conventional foundation is a big job. The bottom part is the footing. It is wider than the foundation wall and placed approximately one foot below the frost line. Footing distributes the weight of the house and prevents the house from moving. The footing supports the foundation wall, which is also poured from concrete. Both the footing and the foundation wall must be reinforced with rebar. The foundation walls further contribute to the sturdiness of the house by using anchor bolts to stabilize the walls. The next layer is rigid insulation. This provides added protection against the elements and potential flooding. A concrete slab is poured over the insulation. This concrete slab will become the floor of the home.
Monolithic domes are constructed on an entirely different principle. David South,
Co-founder of the Monolithic Dome Institute and Monolithic Constructors, Inc. explains, "In a monolithic dome, we hold the foundation together with the house, with this super strong dome. It's like a bowl --you set the bowl down and it doesn't need anything special to keep it in place."
Monolithic domes are made from one piece construction, so there is nothing to hold together. By definition, the strength of the dome comes from the top. The point where all the arcs meet is the strongest point of the house.
One of the advantages on not needing a conventional foundation is flexibility. In areas where the ground moves because of earthquakes or shifting tectonic plates, a monolithic dome will shift with the moving ground. A conventional foundation will crack under repeated shifting or movement.
"I'm in the "blackland" part of Texas where the ground moves all the time. I just build the houses so they float. I pour the concrete floor first and attach it to the dome, and the dome holds the floor together," says David South.
To build a monolithic dome home, first they clear the area where they will build area is prepared, leveled and a vapor barrier added. Next the form boards are added. Just inside the form boards, a one foot trench is dug, then rebar is installed.
David South tells us, "The only reason that I put a foundation, I suppose -- digging down in the perimeter, is so that the skunks don't have a place to get underneath. I turn the edges down an extra foot so that the owners don't have to worry about a skunk digging under their houses."
The trench is optional and does not effect the safety or stability of the home.
"Other than that, I could just pour it on that four-inch slab," says David.
Eliminating the need for conventional foundation makes the monolithic dome safer in earthquake areas and also gives a degree of mobility to the home.
Says David South, "If you had a great big fork lift, you could just come under it and pick it up and go move it. It just totally sets construction on the other ear."
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