Second Floor in a Geodesic Dome?

What about all that space up above in a large dome?  Are we restricted to just using the ground floor?  Is there any way to efficiently use the geodesic structure to take advantage of that upper space?

In the medium-sized dome range, the 6 meter (19.7’) diameter dome is probably the most popular.  The 3V 5/9 configuration is the one that we sell the most of.   This creates a spacious dome with 285 sq. ft. of floor area, and an internal height of almost 12’.  We’ve heard of a lot of our users building a second level, but they’ve always been supported from the floor area, which seemed to us to minimize the inherent efficiency of a dome that has no internal supports.  One of the biggest architectural advantages of domes is that they have no columns within the structure to obstruct the floor level.  So what would happen if you suspended 5 sections independently from the top pentagon and then attached them to the sides, above head-level?  There’s only one way to find out, so we took an existing 6 meter 3V 5/9 dome, and built those attachments.  The result is a dome that has all the benefits of open space on the ground floor, but also uses a good proportion of the upper area that is normally just open space.  Why is this useful?  If you’re doing a Martian habitat simulation, it can sleep 5 people on the second level, and have plenty of space for all their personal stuff, while leaving the entire ground floor open for group gatherings, experiments, or growing potatoes.   If you’re camping in the desert with 5 people, and everyone wants their own space, this might be a be a convenient way to go.  If you’re using the dome for storage, there’s all of a sudden another 200 sq. feet of usable storage area.  Even if you’re using it as a shelter for only two people, this gives you a lot of ‘attic’ room to store all your stuff so it doesn’t clutter up your living room.

Same dome with suspended supports

So how did we build it?  What did we use to suspend the struts from the top pentagon?  These are T-slip joints, designed to go around the 1 ½” struts themselves and then connect to another piece of tubing.  We connected them with the same 2 ½” stainless steel bolts that we use for the rest of the dome.  Then we used 3-way connectors as elbows to connect the platforms.  We cut 2’ off the long end of some ½” plywood, and then cut slots where the vertical supports meet the laterals.  We tapered the sides by 4 inches on a side, so that they keep the 4’ width on the wall side, and it’s only 40” on the middle-facing edge.

Looking up from below at the top pentagon (bottom of picture)

Is this a product we intend to sell someday?  Probably not.  There’s a lot of liability when you start suspending stuff with people down below.  But that doesn’t mean you can’t do this on your own.  Half the fun with the domes is experimenting and seeing what you can design that no one has ever designed before.  If you do build something like this, be sure to do your own testing to find out what the weight limits are before you invite all your supersize friends to join you for a sleepover.

Our warehouse manager, Ed, weighs in at a little over 350.

With all five platforms installed, you can really appreciate the extra space this gives.

 The platforms are suspended from the top, using the sides for support.

There’s about 76” of clear space under the platforms, enough for the average Joe.

Why does this even work?  Why doesn’t it collapse from the top center with all the weight?  The geodesic structure is angular, not round.  The struts coming out of the top pentagon connector can’t sag inward because they are held together on all sides by other connectors that share the force of the stress.  Are there limits?  Of course.  Come back next week, and see the results of our load test.  One of the best parts of R&D is getting to break stuff in the name of science.  We’ll find out exactly how much this configuration will hold before it fails.