The Geodesic Dome Framing Model Renderings
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Geodesic Dome Framing Model overview
The Geodesic Dome Framing model depicts a 36'-0" diameter six frequency geodesic panel dome. The panel framing plan eliminates the need to design and then pay someone to fabricate custom precision metal hub ties. The size and frequency of this dome were chosen so that each of the cord factors for the unique framing members are less than 4'-0" long while enclosing about 1,000 square feet with room for a loft. This is advantageous because two studs can be cut from a single 8'-0" long 2x4 as can two plywood triangles for the exterior and two drywall triangles for the interior from a single 4'-0" x 8'-0" sheet to minimize waste and reduce material costs. The drywall and plywood triangles can be quickly and accurately cut using a CNC router table. The color coding indicates which framing members are identical. The dome was originally generated using SketchUp and then imported as a mass family into Revit. This was my first project using SketchUp.
The dome is not parametric and is only applicable for the intended size and frequency. My intent at this point is to import the .skp file into Revit and assign the dome to a Revit mass family then render the result sitting upon a concrete pad. Once that is accomplished, then I may attempt to recreate that panel dome (or another combination of size, frequency, or stud dimensions) from scratch all within Revit. There are some tools in SketchUp that do not appear to directly correlate to similar tools in Revit so it will take some thinking before I can confidently make another dome all within Revit, but that is the eventual goal.
The skeleton of an icosahedron using golden rectangles where each vertices sits directly upon the surface of a sphere of the intended size was generated. A single icosahedron face that was divided into six frequencies was projected out from the origin point of the icosahedron skeleton to three vertices. Using that template, each triangle was formed by projection from the origin point of the icosahedron skeleton and rough 2x4 studs were generated around the perimeter of each triangle. Then it got tricky essentially cutting each individual stud to size from the triangle frame and adding a color code. Once the individual studs for the nine unique triangles were generated forming a third of a full icosahedron face, the framing for the third of an icosahedron face was copied and rotated into place until a complete icosahedron face was generated. The framing for the full face was repeatedly copied and rotated into alignment until a little more than half of a sphere was generated into a sort of helmet shape. Two of the full faces were deleted from one of the ears of the helmet and the framing of the resulting half sphere was copied and rotated until a complete geodesic sphere was realized. One of the true flat seams formed by the framing was located in the geodesic sphere and the framing for half of the sphere was eliminated to that seam. The resulting framing of the dome was rotated into a horizontal position. Finally, the triangles that form a door opening were deleted.
Geodesic structures have fascinated me since reading “Dome Book 2” (published in 1971) as a kid at my local library. I can create a panel dome framing plan for any size/frequency dome using SketchUp and hopefully soon in Revit. As the studs are all slightly set at a taper as projected from the center of the icosahedron, the resulting joints are very strong and may only require glue, but wood screws or bolts should be used for safety. This panel plan methodology allows you to cut the studs using a compound miter saw and pre assemble the triangles in your home garage or workshop before assembling the dome at the building site. The studs could be routed if a flush face for each triangle is desired or let the plywood faces of the triangles sit on top of the studs. The surface could be finished with stucco or some other water resistant material. Insulation and drywall or paneling can finish the interior. If this dome were actually going to be built, 2x6 lumber should be used so that additional insulation could be packed into the walls.
This project is still a work in progress.