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4 V construction Diagrams
With a close look you will see that Dome Kits uses a different geodesic geometry to simplify the manufacturing and construction methods. The original 4V history uses 6 cord factors with the letters B and C very close to the same. On spherical geodesic structures over 50 feet in diameter this difference can begin to be a concern in more accurate connection systems. To make construction of 4V geodesic dome kits more user friendly. Dome Kits has combined the B and C cords and lettered them C's. We have renamed the F cords as B's.
Looking at the top down on the 4V hemisphere we can see the five major triangles that make the Icosahydron cap. The A struts connecting at the centers of the pentagons. Following the A-B-B-A struts you can find the corners and (pentagon centers) of the major triangles.
There are four struts that run from corner to corner of the major triangle. This is why it is called a 4 frequency geodesic structure. There are twenty major triangles to create the complete 4V icosahedrons sphere. Five on each of the ends and ten facing each other around the middle or center.
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The side view showing the great circles are represented by the letters D. One of the construction advantages of the 4 frequency icosahedrons is the horizontal great circle at the hemisphere which greatly simplifies the connection to the foundation and eliminates the need for rectangular riser walls. This diagram shows one row under the hemisphere that may be used for extra interior height in smaller spherical geodesic structures.
4 V Side View
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The cord lengths are calculated by multiplying the formula X the diameter you wish to build.

Example for 24' diameter dome

A - 1.52 (30 struts) _____1.52 X 24' = 36.48 -- 36"-1/2"
B - 1.79 (30 struts) _____1.79 X 24' = 42.96 -- 43"
C - 1.76 (90 struts) _____1.76 X 24' = 42.24 -- 42"-1/4"
D - 1.88 (70 struts) _____1.88 X 24' = 45.12 -- 45"
E - 1.95 (30 struts) _____1.95 X 24' = 46.8 -- 46"-3/4"

Your measurements are calculated in decimals. If you round them off to the nearest 1/4" you should be fine. The 24' diameter was chosen because the longest strut is the E strut with a final length of 46-3/4". Using cross Tee's with a length of 47-1/4" we could not go much longer. The 30' diameter is ideal for 10' strut material and 4' sheet materials. The 39' diameter optimizes 12' long strut materials. Lumber prices have caught up with the light gauge steel prices. Light gauge steel offers many ecological and structural advantages over wood structures. Dome Kits may be the only dome kit manufacture to offer this advanced building material in a spherical geodesic structure.
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On spherical geodesic structures under 35' in diameter the use of a riser wall can be used to gain extra interior ceiling hight for the second floor. As shown in this diagram there are five E-E-E triangles and five C-C-C triangles around the lower level that are horizontal and lend themselves for simple framing of vertical wall sections 4' to 6' wide for conventional windows and doors. This shows another of the advantages the 4V Icosahedrons has over the 3V. You may not desire to use all 10 locations for windows or doors but at least you have the option. In using the TRIANGULATED riser wall you will be keeping the shear quality and structural integrity of the spherical geodesic structure. You may remove some of your C and D struts in your window and door areas. These can be used at higher levels if you don't complete the frame before adding your openings. Try to keep your D struts at the hemisphere horizontally flat and level to ensure you have no problems finishing your geodesic structure. All geodesic structures are sensitive to being out of round and this can cause difficulty during construction. This geodesic geometry is not the same as others but has been built over one hundred times successfully by owner builders.
10 Sided Riser Wall
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