The geodesic dome, designed by Buckminster Fuller in the early twentieth century, is one of the most efficient homes ever devised. Construction of a basic concrete dome is considerably less expensive, and takes less time to build, than a conventional home.
- Skill level:
- Moderately Challenging
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Things you need
- 30 pieces 3/4-inch electrical conduit pipe, 3.5 feet long
- 40 pieces 3/4-inch electrical conduit pipe, 4 feet long
- 40 pieces 3/4-inch electrical conduit pipe, 4.1 feet long
- 46 5/16-inch grade 5 bolts, over 3 inches long
- 92 5/16-inch washers
- 46 5/16-inch nuts
- Zip ties
- Large roll of heavy wire mesh (over 350 square feet)
- 10 bags (or more) mortar-grade concrete
- Concrete mixer or wheelbarrow and hoe
- 5/16 socket driver and pliers
- Metal saw
- Arbor press or hammer and anvil
- Ladder or trestle
Clear a 314-square-foot area for the dome. Preferably the ground should be concrete.
Cut the electrical conduit pipe to the lengths listed in Things You'll Need, since the pipe is sold in 10-foot-long pieces. Flatten all of the ends with the arbor press to a depth of 2 inches. Align the flattened ends so that they are at the same angle.
Bend each end to between 9 and 11 degrees, in the same direction. It should have a "C" shape to it when done. Using the drill, place a centred hole in each flat part of conduit to accommodate the 5/16 bolts.
Label all the electrical conduit struts A, B or C (A is 3.5 feet, B is 4 feet and C is 4.1 feet). Lay out the bottom ring of struts, according to the diagram, in a C, C, B, C, C, B pattern.
Place bolts in each connecting hole, without nuts. Assemble the next "layer" of struts by placing the ends onto the bolts, working around the ring until the second layer is standing. The initial ring of struts can be locked down with washers and nuts now that it is complete. Do not tighten these nuts yet because the weight will shift until the dome is complete.
Place nuts on the second layer of struts after adding the third layer. These may hang down or go off in strange directions until they are affixed to the very top of the dome. Once the second layer is completed, the assembly diagram should be easy to understand and follow.
Leave the nuts loosened until the dome is complete, then walk around the dome and check measurements to ensure it is centred.
Tighten all the nuts for every vertex. Each point will have 4, 5 or 6 struts connected with a bolt and take most of the structural stress, so make sure they are all very tight.
Fasten the wire mesh to all of the open triangular areas. Using the zip ties and the ladder, stretch the mesh across each strut and use the ties to hold it. Cover the entire structure with the mesh, making sure it does not sag on top. It is a good idea to do two layers of heavy wire mesh, overlapping them. Apply zip ties liberally; it is impossible to have too many. The mesh should "rest" on the dome struts, held in place by the ties, not supported by them. Leave enough of an opening for entry!
Mix the cement, one bag at a time, and spread it onto the dome. The concrete should be mixed a little thick so it will not drip through the mesh.
Spread the concrete evenly, from the bottom up, so it will dry correctly. A thickness over 1 inch is desired, but spreading it too thick can cause it to crack while drying. Spreading from the bottom up ensures that each successive layer of concrete will "seal" the previous layer, weatherproofing it. Once dry, the interior can be insulated and floored.
Tips and warnings
- Concrete must cover the bolts and vertex areas.
- Doors and windows must be accommodated for, before pouring the concrete.
- Removing one or two struts can give a larger opening.
- Use safety glasses and protective gear when around power tools.
- Do not stand or hang from the dome structure until it is complete.