Every time we share the Thiosphere project, someone asks: why not a geodesic dome?
It is a fair question. Geodesic domes are legitimately strong structures. Buckminster Fuller demonstrated in the 1960s that a network of triangles distributed over a sphere creates one of the highest strength-to-weight ratios possible in architecture. The math is elegant. The structures are striking. The engineering is proven.
We chose a different path — not because domes are bad, but because modularity demands a different geometry.
What Domes Do Well
Credit where it is due. Geodesic domes have real structural advantages:
Strength per material. A dome distributes loads across its entire surface. There are no single points of failure. Wind, snow, and seismic forces spread evenly through the triangulated network. Pound for pound, a geodesic dome encloses more volume with less material than almost any other shape.
Wind resistance. The curved surface deflects wind rather than catching it. There are no flat faces to act as sails. In high-wind environments, domes perform exceptionally well.
Spanning ability. A dome can cover large areas without interior columns. The geometry is self-supporting. This makes domes excellent for warehouses, event spaces, radar installations, and other applications where unobstructed interior volume matters.
These are real advantages. If your primary design constraint is enclosing the maximum volume with the minimum material and no internal supports, a geodesic dome is hard to beat.
Where Domes Fall Short
But greenhouses, saunas, offices, and backyard shelters have different constraints. And this is where domes get complicated.
Flat surfaces are useful. Furniture, shelving, benches, raised beds, windows, doors — nearly everything humans use inside a building assumes flat walls and a flat floor. A dome has neither. The curved interior surface means you lose usable space near the edges where the wall meets the ground. Bookshelves do not sit flush against a curve. Standard windows do not fit curved openings.
This is solvable — you can build internal flat walls inside a dome — but then you are building two structures: the dome and the interior fit-out. The elegance of the geometry works against the practicality of the space.
Every panel is different. A geodesic dome looks uniform, but it is not. Depending on the frequency (the number of subdivisions), a dome might have three, five, or more distinct triangle sizes. Each size needs its own template, its own cut list, its own assembly position. The higher the frequency (and the more spherical the dome), the more unique panel types you need.
For a DIY builder, this means more complexity. More measuring. More chances for error. More pieces that look similar but are not interchangeable. A 3V geodesic dome has 9 different strut lengths. A 4V has 18. Label one wrong and the whole section fails to close.
Connections are complex. Each vertex in a geodesic dome is where five or six struts meet at precise angles. The hub — the connector at each vertex — needs to accommodate these specific angles. Commercial geodesic hubs are expensive precision components. DIY alternatives (pipe flattening, bolt clusters) are fiddly and often leak.
Compare this to the Thiosphere connection system: flat panels meet at consistent angles, attached to a standardized frame. Every panel connection works the same way. Every panel of the same type is interchangeable with every other panel of that type.
Waterproofing curves is hard. Flat panels seal with gaskets, caulk, or overlapping edges — techniques that builders have used for centuries. Curved surfaces that meet at compound angles require custom flashing, flexible sealants, and careful detailing at every joint. A dome with 80 triangular panels has 120 edges to seal. Each one sits at a slightly different angle to gravity, which means water runs differently across each joint.
This is the number one complaint from people who have actually lived in geodesic dome homes: they leak. Not because the geometry is wrong, but because waterproofing compound curves at scale is genuinely difficult.
The Modular Argument
The Thiosphere uses a prismatic geometry — flat panels arranged in a roughly cylindrical form with angled roof sections. It is not as mathematically elegant as a geodesic sphere. It encloses slightly less volume per unit of material. In a pure engineering comparison, the dome wins on paper.
But we are not optimizing for volume-per-material. We are optimizing for something harder: modularity.
Modularity means that every panel of a given type is identical. Not similar — identical. The same CNC file, the same cut list, the same assembly process. A wall panel from a Thiosphere fits a Saunosphere fits an Agrosphere. A door panel is a door panel, regardless of which module it connects.
This is only possible with flat panels. The moment you introduce curvature, panel geometry becomes position-dependent. Triangle A3 is not the same as triangle B2, even though they look alike from across the room.
Flat panels also mean standard materials. Plywood, OSB, rigid insulation, glass, polycarbonate, metal cladding — all of these come in flat sheets. Cutting flat panels from flat stock is efficient. Minimal waste. Simple tooling. A table saw and a drill press handle 90% of the fabrication.
Curved panels require bending, laminating, or molding. Each of these adds cost, tooling, and skill requirements that put the build out of reach for most self-builders.
Docking and Expansion
Here is the constraint that really drove the decision: domes do not dock cleanly.
Connecting two geodesic domes requires cutting openings in curved surfaces, building a transition structure between two different curvatures, and sealing compound curves against compound curves. It is possible — but it is a custom engineering problem every time.
The Thiosphere modules connect through standardized flat door panels. Two modules dock by aligning their door panel openings. The structural frame of each module remains independent. No custom transition piece. No compound curve sealing. The connection works because the interface is flat.
This is what makes the multi-sphere configurations practical. A duo in a parking space. A trio in an L-shape. A cluster of five around a central courtyard. Each configuration is just standard modules connected through standard door panels.
Try that with domes and you are in bespoke architecture territory. Beautiful, but not modular. Not repeatable. Not something a homeowner builds in a weekend with a friend.
The Hybrid Question
Could you build a structure that combines geodesic strength with modular flat panels? Something dome-like in overall shape but made of standardized flat sections?
You could. It is called a truncated icosahedron — a soccer ball shape. Or an octahedron. Or any number of polyhedra that approximate a sphere using flat faces.
The problem is that these shapes either have too few faces (meaning each face is large and structurally weak) or too many unique face types (bringing back the complexity problem). The geodesic dome itself is actually this compromise taken to its logical extreme — a polyhedron with enough faces to approximate a sphere, using as few unique triangle types as possible.
The Thiosphere geometry is a different compromise. Fewer unique panel types than any geodesic frequency. Flat surfaces that accept standard materials. Docking interfaces that work identically every time. The trade-off is a shape that is less spherical and encloses slightly less volume per unit of material.
For a structure that one or two people build in a backyard over a few weekends, using materials from a standard building supplier, and that can connect to other structures of the same type — we think that trade-off is worth it.
Both Can Exist
This is not a competition. Geodesic domes are excellent structures for specific applications. If you are building a single large-span enclosure, a radar cover, an event space, or an architectural statement, a dome might be exactly right.
The Thiosphere is designed for a different use case: small, modular, expandable, DIY-friendly structures that connect to each other and adapt over time. That use case demands a geometry that prioritizes panel standardization and docking compatibility over pure structural efficiency.
The strongest structure is not always the most useful one. The most useful one is the one you can actually build, modify, and expand as your needs change.
Explore the Thiosphere Platform — the base module for every configuration
Design Your Layout — connect modules and see what fits your space
Read the Hardware Docs — full build instructions and panel specifications
Join the Discussion — dome enthusiasts welcome