This article is an excerpt from the article "The Monolithic Dome".

Monolithic Dome Shapes

by David B. South

Here are most of the pure geometric shapes we use in designing the Airforms that are inflated to build Monolithic Domes. These shapes are shown individually. But they can be intersected with each other to provide additional combinations. And their connections can be smoothed to better define the sculptured shapes. In addition to these regular shapes, others can be airformed as well.

	Perspective	Top	Side
Low profile spherical segment: This is the most efficient shape to cover the greatest amount of floor space. Especially useful for large domes.
Hemisphere: Surface area is double the floor area. Useful for high volume storage buildings and smaller structures, such as homes.
High profile spherical segment: The most volume for the least floor area. Ideal for water tanks, storage buildings, unique looking homes and golf course club houses.
Oblate ellipsoid: Very efficient for single floor structures, such as a home or school. Walls have maximum vertical slope vs structure size.
Prolate ellipsoid (Long Axis Vertical): Mostly useful for bulk storage. It is very tall vs its footprint. Extremely strong for an underground or buried building.
Prolate ellipsoid (Long Axis Horizontal): This dome literally leans out from the floor level before curving over the top. Elliptical base creates a very unique space.
Torus: Not as space efficient as a dome, but it has some fun applications, i.e. a home with a center courtyard or garden.

FAQs about Monolithic Dome shapes

1) Since the center section is not constructed in a torus, is it less expensive to build?

Actually, no. The dome curves in on itself again to make the tube, thereby increasing the surface area of the dome shell.

2) What is the usual size of a torus and have you ever built one?

A common home size is 66 feet in diameter with a 32-foot diameter center section. It definitely can be much larger. So far, the torus has failed the cost test. A Monolithic Dome of equal size is about the same price.

3) What is the maximum height at the center of an oblate ellipsoid style dome?

An oblate ellipsoid is an ideal shape for homes and one-story buildings. It brings the height of the dome down; but the walls at the base are more vertical so it provides more shoulder room. In general, an oblate ellipsoid should not have a minor-axis-to-major-axis ratio greater than 1.45. Consider a 32-foot diameter dome. The major axis is 16 feet. Divide 16 by 1.45 and the minor axis is 11 feet.

If we wanted the building to be two-stories high, we would put a 7-foot or 8-foot stemwall under the elliptical dome for a total height of 19 or 20 feet. The Oberon plan ("Dome Living: A Creative Guide for Planning Your Monolithic Dream Home", pp. 64-67) is an oblate ellipsoid, 32 feet in diameter and 12 feet tall. It makes a nice, one-story home with one, two, three or even four bedrooms.

4) The prolate looks as though it may have better interior feel and window options. Am I seeing this correctly? Sometimes a prolate fits the lot better. Rarely does it make the windows or shape better. Mostly, it may look better on paper; but in reality, you cannot see anything but a small part of it from the street or inside. There is very little benefit to the prolate, except for site considerations. Eye of the Storm has the long axis parallel with the beach; therefore more beach can be seen from the house. The house still looks circular from the beach. It also looks circular from within. It just has more exposure to the ocean because it is a prolate. The prolate costs more per square foot. It takes more material to enclose a smaller space than a traditional circular shape.

5) Are profiles other than the circular and elliptical available?

Yes -- we can do cones, cylinders, parabolas, some hyperbolics, and some sculpted shapes. Air tends to blow round, therefore at least one dimension of the Airform must be round. The only limitations are that it must be inflatable and engineerable.

This article is an excerpt from the article "The Monolithic Dome".

Monolithic Dome Shapes

Perspective

Top

Side

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