Building the Mini Dome

I designed and built this 308-sq-ft accessory structure in the backyard of my Portland, Oregon home.

Its a super-insulated mini geodesic dome and the world's first pentakis dodecahedron home. The unique shape allows every triangle to be identical in shape, size, dihedral angles, and strut lengths.

Build cost: ~3,100 hours and ~$100,000 USD (including all fees, materials, and furnishings).

Website: DodecaDomes.com

The following is a brief overview of the construction process.

Prefabricate the struts, panels, floor framing, room framing, and rebar cages.

Dig the holes and pour the concrete piers.

Trench and run the sewer, water, electrical, and data conduit to the stub-out locations.

Frame the floor, inner wall, outer wall, and install the sheathing.

Apply an underlayment, install the windows, cover the crawlspace, and install the front door.

Install roof joist supports and paint the door frame. Cut and install the metal shingles, the flashing, and the vents.

Install the window weep tubes, HVAC ducts, waste pipes, water conduit, data conduit, electrical conduit, utility closet drain, and thermostat conduit.

Install the window blocking, support column, brackets, vent pipes, door wall, and HRV ducts. Re-torque all connections and apply a wood treatment.

Have the dome sprayed with closed cell, 2lb, high lift, HFO blower, low VOC, polyurethane foam. Cured SPF is inert, odorless, and does not off gas.

Seal the floor beams, cut and install mineral wool, and screw down the subfloor.

Erect the interior walls, plumb the vent pipe, frame the upper floor, install the shower, build the water heater shelf, and install the upper subfloor.

Install the panel, HRV unit, and electrical boxes. Wire the feeder and branch circuits.

Run tubing to all fixtures, install the water heater, and connect to the water supply.

Cut and secure the mineral wool into the walls.

Install blocking, hang the bathroom door, install plywood panels, cut and hang drywall, apply and smooth drywall mud, and primer the walls.

Sort planks, create a cutting jig, cut panels, mark screw locations, apply a wood finish, and install the panels.

Hang the upper cabinets, secure the countertop, install the sink, fit the utility doors, and panel the backsplash.

Fill exposed fasteners with wood putty. Cut, finish, and install the trim pucks and trim straights.

Caulk the shower and inside corners. Paint the bathroom door, utility door, walls, and front door.

Cut, weld, and grind the metal pieces. Have them powder coated.

Cut and install the wooden trim, install the frosted acrylic, and install the metal window buck trim.

Install the spiral staircase and railings.

Finish the electrical, plumbing, doors, vanity, cabinets, utility closet, and bathroom.

Modify a mini PTAC unit. Install it outside and duct it to the inside.

Install the uppler flooring, prep the main subfloor, and install the main flooring.

Measure, cut, finish, and install the door casings, baseboards, and panel trim.

Install the toilet, refrigerator, dining table, sofa bed, TV, bed, side tables, and many other smaller items.

Make room for the porch, pour the foundation, build the frame, and surface the framework with planks and handrails.

Landscape and photograph the finished product.

For more photos, info, or to purchase my book please visit DodecaDomes.com.

Thanks for checking out my projects.

-Josh!