Tetra - Dome -X2 Greenhouse
The dome already assembled, was lifted up on bricks for the Base Option retrofit. This is the hard way to do it - best to work from ground up. Base rectangles have OSB board siding, painted with aluminum roofing paint on the outside and white paint on the inside. All the dome struts were painted white.
Adding a 2 ft Vertical Base to the Tetra-Dome

X1 struts were added and the OSB and dome struts painted.

Main dome struts are 2 x 4, X1 struts are 2 x 2.
Concrete bricks and blocks provide anchoring weight inside of the dome after it is covered.

Entrance area with the only miter/bevel board. Six foot ladder shows size proportions.

This lower triangle is a window area where the poly can be detached and rolled up to the upper edge that is permanently attached. Polyfastener is used for the removeable edges. Covering is 10 mil Super Poly.

 "X2" - more right triangles made with further subdividing.

 X2 struts were added to these rather large triangles, working from inside after the covering was installed.

These X2 struts help prevent cover from flapping in the wind.

One large triangle is a roll up window with removable strut for ventilation and getting large items in/out. A smaller upper triangle is also a roll up window.

This view is looking at a connection of 2 x 2s to the main 2 x 4 strut. Simspon Strong Tie 4-way connectors are used (in place of Connector Hubs, see drawing below), with screws and wood block underneath to support X2 boards coming in at 45°.

Looking North, shade in the morning and full sun all afternoon.

Only one compound miter (bevel + miter) cut was needed - for the vertical board at the entrance shown here. Notice how the Super Poly reflects light. Inside is brighter light than on outside.

Four months later the dome has aquired a makeshift anti-cow fence.
Remaining 8 X2 strus have been added (not shown here) with a door and plans for vinyl or metal siding attached to the Base.

I use this dome for work and storage. It has a potting bench and cactus garden, fan, lights and is very functional.
The floor is dirt for future gardening.

This is the ~17 ft diameter dome made with longest struts nearly 10 ft. (actually 116 inches). With ~12 ft boards the diameter approaches 20 ft.
Original dome (top + geodesic bottom) with 2 baby black angus:
X1 struts were added to give extra structural strength and support for the large sections of Super Poly. Additional 2 x 2 "X2" dividing struts were added, joined from Simpson Strong Ties to the Connector Hubs, making a total of 48 right triangles (no hexagons or pentagons on this dome!). These smaller triangles help prevent the poly from flapping in the wind. The dome still has some finishing touches to be appplied: more sub-dividing struts (done), entrance door (done, made from Coroplast), Cinchstrap (pvc lath stapled over the struts) (done), additional siding on the bottom, etc. The dome survived the recent thunderstorms in the area that downed trees, power lines and blew over trucks and mobile homes (Georgetown, Tx. October 15, 2001).

This illustration shows the basic design, Tetra - Dome X1 + Vertical Base Option and door rough-in frame. Proportions are for a smaller dome on a 4 ft Vertical Base Option.

Tetra - Dome X2

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Tetra - Dome Matrix Part 1
More type X2 Illustrations: Tetra - Dome Matrix Part 2