Octahedral domes have their
own unique symmetry patterns. You see squares in place of the familiar
pentagons of icosahedral
domes. These can be adapted for standard rectangle/square windows,
skylights and doorways. Domes make nice greenhouses and shelters
for many uses. With architectural development, larger domes can be
fully
functional economical earth friendly/user friendly homes or commercial
buildings.

Dome Termminology

Orientation:Typical up-down axis for a convenient mid-point or hemisphere dividing line. This is the 'normal'Square Zenithorientation. This means the hemi-sphere ground perimeter (dome base) is flat for building on the ground/foundation. Other orientations areFace Zenithwith triangle face at top, andEdge Zenith, with a strut (edge) at top. In some cases, the base perimeter struts are altered to make flat and level.

Frequency:Number of times the triangle face of the original polyhedron is divided into more triangles.

Class:Dividing lines are along those of the original polyhedra (Class I), or turned 90° (Class II). Class II types come in only even frequencies, 2, 4, 6 etc. See "Geodesic Math and How to Use It" by Hugh Kenner.

Octahedron and top half, divided in Class I two and three frequency grids

Octahedron 1 frequency, as a hub-strut pyramid

**2.** 6-way vertex at the top. This
is the **Octa
Dome 2 HZ = Hexagon Zenith** with a 6 sided base and a very nice
and simple tall dome with unusual octa symmetry. Floor level cut-off
might
also be at the half way (hemi-sphere) point. Notice the vertical square
areas front and back. Here doors and windows can be added, or more
domes
connected.

__Class II - two examples__

**1.** First example shows how it is equal to the Tetra-Dome.
"Class"
in dome terminology defines if the dome division is parallel to the
underlying
polyhedra or turned 90°. The Class
II type are with divided triangles 90°
from the octahedron. Please refer to the **Tetra-Dome**
pages for more information.

**2.** Second example is the dome
above turned 45°
to produce an edge or strut at the top, the Edge Zenith (EZ). This is
same as the **Tetra-Dome
EZ**. It's the best dome shape for simplicity, with only 10
Connectors and 21 struts needed, after the Icosa-Dome
which has only 11 Connectors and 25 struts.

**OCTA-DOME
3 (3 frequency)**

Three examples

**1.** First is the 4 way vertex at the top (Square Zenith). This
orientation gives
central dividing line, a 1/2 geodesic = hemisphere dome.

We made a small Octa Dome 3 and made it our "Vine Dome"

**2**. Second is turned 45°
to put a hexagon at top making the Hexagon Zenith (HZ). Floor level
below the halfway point provides a
nice dome with extra height (cutoff plane is lower than the hemisphere
line).

**3.** The Edge Zenith (EZ)
orientation with a strut at the dome top presents another
interesting configuration. Floor level is even with the bottom struts
of two opposite
squares and provides another dome with extra height, near 5/8 fullness.
Square
area can be used to fit regular doors and windows, or openings large
enough
to drive in a vehicle - car, boat, RV - etc. This one could also
be easily divided at the hemisphere for a shorter dome.

**Octa-Dome
4 (4 frequency)**

__Class I - three examples__

**1.** First - "Normal" SZ oientation, with a level of
triangles
below the hemisphere used to add height (a Base Option) . Some of the
bottom
strut lines are modified to give a flat, horizontal ground level.
Bottom
triangles continue the dome's roundness. Lower hexagons are vertical,
making a good place to add a door

**2.** HZ - Hexagonal vertex is
at the top. Similar to the Octa-Dome
3 above, the bottom squares are kept for a taller dome with more
volume,
and several lower struts (shown in blue)
are
altered for a flat base.

**3.** FZ - Face Zenith dome gives
another interesting variation. The
orientation provides a hemisphere for a 1/2 dome and a base with 12
sides.

**The Double Dome concept demonstrated with this dome -** **Double
Domes**

**A study of the Octa-Dome
4 and the square/hex/face zenith orientations done with 3d surface
shading.**

__Class II - two examples__

**1.** SZ - Square Zenith with a 4-way vertex on top. As with
previous examples
the lower squares remain intact producing area below the half way
point.
Ground level struts (blue) are altered to
give a flat base.

**2**. HZ - Orientation with a hexagon
vertex on top. A geodesic hemisphere
is produced which makes a convenient dividing line for a dome with a 12
sided base.

Octa-Domes such as shown above can make nice observatory domes with a convenient opening for telescope viewing. A fully rotate-able dome can be made by using grooved wheels attached to ground level Connector Hubs. The grooved wheels follow a round track that is the diameter of the bottom perimeter. Typical metal grooved wheels will support 300 lb. each which is more than enough for most small observatory domes. Please write for more details. See also: Observatory

**Octa-Dome
5**

**1**. SZ - First example with a 4-way
vertex on top.

**2.** Edge Zenith type with a strut
at the top. Modified struts
at the bottom provide for the flat ground perimeter.

An info
page on the Octa Dome 4 an 5 Extended (XT) versions

**Octa-Dome
6 (6 frequency)**

__Class I__ dome, drawing of normal
orientation with 4-way connection
at top.

Octa-Domes are easily halved for convenient attachment to a vertical wall. Most orientations produce a cutting plane of struts that will produce a half dome or 1/4 sphere. Here a 6 frequency Class I dome as 1/4 sphere is shown. Colors show different types of struts. Each type has a particular length, angle, orientation on the dome and angle/orientation on its particular Connector Hub location.Photos of a 2 x 2 and 2 x 4 dome

The 1/4 dome (1/8 sphere) can be mounted against two vertical walls in a 90° corner.

**1**. __Class II__ dome, drawing
of normal (SZ) orientation with 4-way
connection at top.

**2**. __Class II __
Edge
Zenith hemisphere dome.

The Octa Dome 4 SZ is a four frequency octahedral dome with the
square at top,

shown above as a 20 ft diameter 2 x 4 dome with the Base Option, made
from 2 x 4 wood.

Four lower hexagon areas are vertical, making a good place to add a
door and windows.

More details here>>
with new 3D renderings.

Visit our Octa Dome page

and the

Cube-Octa dome

with it's Simplified Version

the Rhombi-Cobe-Octa is another excellent octahedral based dome

and our "TR-CO" is the Truncated Cube-Octa Dome

NEXT - CUPOLAS

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