Utility Dome Extensions

We just finished sheathing our extensions!

A partially completed geodesic dome with an extention
Wooden Igloo!

The Utility Dome is a sawtooth style dome, which is Natural Spaces Domes’ name for a dome shell shifted so that there is a hexagon at the top instead of a pentagon. The vertical riser walls are then angled at top, instead of forming a horizontal ring to begin the dome struts.

2 arches attached to one side of a geodesic dome; 1 arch attached to the other
The lower, darker colored portion of the dome shows the sawtooth shape

Since the Utility Dome has two uses, we wanted a separate entrance for each side. The north side will contain the inverters, batteries, etc. for our off-grid power. The south side, plus the loft above the electrical room, is destined for storage of stuff.

Looking into a partially completed geodesic dome with a person cutting plywood inside
Jon trimming some plywood to match the angle of the dome shell

Each side has an extension to create a covered entryway.

A geodesic dome with 2 extensions at 180 degrees
We probably would have preferred to have the extensions at an angle other than 180 degrees, but the dome is so small that we only had that option. Our neighbor calls it the Bigloo 🙂

The Greenhouse Dome has a tiny version of an extension for the door. Alternatively, the MinneDome is cut away to have vertical walls and the exterior door is set in one of those walls.

A man standing in a framed doorway
Jon posing in the future exterior door of the MinneDome, for comparison

The prebuilt arches came in 2 pieces. We needed to make sure the 2 pieces were square and had the correct opening width at the bottom before we fastened them together.

A man carrying a 3 member section of a dome extension arch
Jon carrying the small side of the prebuilt extension arches

Our friend Sarah helped us a few days on the extensions and it was so helpful to have her help us carry and tilt up the big arches!

2 people working to attach an extension arch
Sarah and Jon with the arch, right after we tilted it up

The arches are held to the dome with Simpsons ST6236 strap ties.

An extension with 2 of 3 arches tilted up, attached with some blocking. A large stack of plywood sits in the extension
We thought the south extension would be a great place for the plywood delivery, but then we couldn’t maneuver the scaffolding there- doh!

We measured, cut, and nailed a lot of blocking between the arches.

2 people working on a piece of blocking between 2 arches
Sarch and I attache some 2×8 blocking

Each piece of tongue and groove sheathing was a different size because it had to fit against angled dome shell.

A woman nails a piece of plywood to a dome extension
I had to suck in my stomach in a few places so I wasn’t aiming the nail gun at myself

The last few days were in a heat wave, so we had to take more breaks, but we finished!

A man up at the top of a dome extension
Jon nailing the last piece of plyood on!

2 comments

  1. Looking good!! We’re putting up an extension that’s about the same size as yours (16 foot’ish) and wow there’s a lot more to it than you’d think! Glad to see you got some help!

    1. Thank you! I’m glad you had help to prop the arches up, too! Then there is all the blocking and sheathing- necessary, but less glory.

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