Building My 7-Meter 3V Geodesic Dome from Thunder Domes

By John B., Thunder Domes Customer

When I started looking for a sturdy, customizable structure to store ATVs, snowmobiles, and yard equipment, I stumbled onto the idea of a geodesic dome. What sold me was the strength-to-weight ratio, the aesthetics, and the challenge — and Thunder Domes made it all possible with their 3V Geodesic Dome Bracket Kit.

This is my experience building a 7-meter diameter dome from scratch, using standard tools, pressure-treated lumber, and a lot of patience. If you’re looking for real-world advice on how to build a DIY geodesic dome on a concrete pad, read on.

Building My 7-Meter 3V Geodesic Dome from Thunder Domes

 

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Step 1: Planning the Dome Build

After ordering the 3V dome kit from Thunder Domes, I reached out to Matt with questions about creating a large entrance. I wanted a hexagonal opening wide enough to fit equipment — something around 2m x 2m. Matt suggested blowing out a 6-way hub on the second row of struts, which gave me the confidence to plan ahead for a functional garage-style entry.

The Acidome calculator (linked in Thunder Domes' listing) was invaluable. It let me visualize the geometry, preview dimensions, and get exact strut lengths. The only limitation? It uses metric units, so I built a conversion spreadsheet to work in inches. Not a dealbreaker.

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Step 2: Prepping the Concrete Foundation

I chose to build my dome on a concrete slab for maximum durability. I designed a 15-sided (pentadecagon) pad using:

• 15x 2x6x6’ form boards

• 24° miters on one end for perfect angle alignment

• A gravel base and compacted subgrade

• Standard rebar and welded re-mesh

• 6” slab depth with ~8” margin beyond the dome’s footprint

I even reused the miter jig from this process to bend 10' rebar pieces at 24°, saving time and improving consistency.

Before pouring, I did a “dry run” mockup using my fabricated base struts and connectors. This allowed me to measure chord lengths, verify alignment, and ensure my formwork was justified to the dome’s true center.

Pro tip: If you're building on concrete, pre-position your struts to validate everything fits before pouring. Measuring 15x and pouring once is the way to go.

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Step 3: Fabricating the Struts

Using PT 2x4s, I cut and labeled every strut by type: A (red), B (yellow), and C (blue). The efficiency was incredible:

• A + C from a single 8-ft board = no waste

• B + C with only 1” waste

• Minimal offcuts throughout the process

I used two jigs I built myself:

1. Pre-drill Jig – Ensures perfectly aligned 1/8" pilot holes at each end of every strut.

2. Band Saw Miter Jig – For consistent 24° cuts on form boards and other angles.

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Step 4: Raising the Dome, Level by Level

I worked solo, which made things slower, but also taught me a lot. Each level brought new height and new challenges. Here’s how I handled the build:

Level One (Base):

• I used “Sil Seal” moisture barrier between wood and concrete.

• 3/8" wedge anchors, 5" long — one per strut.

• Some base struts angled outward slightly, so I cut 9° shims from scrap 2x4s to compensate.

Levels Two to Five:

• Built a custom, modular scaffold on wheels, modifying one tower to poke through the dome as needed.

• Used a “finish nail and clamp” system to align struts before fastening — safer and more precise than freehanding on a scaffold.

• Only drove one screw first for flexibility, then locked in the second.

This dome was 7 meters in diameter — roughly 28 feet — and it came together with almost shocking precision thanks to Thunder Domes’ well-designed brackets.

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Step 5: Custom Hexagonal Door System

To make my large door work, I built a compound-mitered hex frame using extra B struts, cutting 26° and 12° angles to fit flush. I reinforced the structure with gussets cut at matching angles.

To open it? A manual winch and pulley system, with 106 lbs of lift for the door section alone. It opens wide enough to walk or drive through with ease.

Later, I discovered the frame flexed slightly once the inner structure was removed. OSB wall sheathing fixed that by reinforcing the shape.

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Step 6: Sheathing and Covering

Instead of buying a dome cover (which is expensive and custom), I opted to sheath the dome in 7/16” OSB panels for now:

• 3 BCC triangles per 4x8’ sheet, sometimes 4 with a 2-piece workaround

• Minimal waste — I’m a geometry nerd, and this was satisfying

• Added 1/4” spacers (sliced from 2x4 scraps) between struts and sheathing to clear connectors

• ~15 nails per panel using a nail gun

This approach provides excellent rigidity, weather protection, and flexibility for finishing with EPDM or PVC roofing later. I’m currently working with a boat shrink-wrap contractor for a seasonal weatherproof solution.

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What I’d Recommend for Other Dome Builders

• Mock up the base before pouring concrete — you’ll thank yourself.

• Use jigs to save time and improve precision.

• Go slowly and level-by-level — especially if working solo.

• Expect some geometric surprises at the top (gravity + tolerance adds up), but Thunder Domes’ system handles it well.

• OSB sheathing adds strength and gives you tons of weatherproofing options.

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Final Thoughts

Thunder Domes delivered exactly what I needed — a strong, modular, customizable 3V geodesic dome kit that I could tailor to my needs. The metalwork is precise, the support was great, and the result is a structure that’s both beautiful and functional.

I'm storing equipment in mine — but these would make killer off-grid cabins, saunas, greenhouses, workshops, or glamping pods.

If you’re ready to take on the challenge, I can’t recommend this system enough. And if you’re just here to geek out on geometry and structural design — welcome to the dome club.

Happy Dome Building!
– John B.