- Any outside wall with an end cap can take a new cube.
- The end cap comes off, a mate package goes on, and the new cube opens into the old one.
- Plan the open side and the ground beside it on day one.
How it works
Every side of every cube is an opening. Inside the bunker, openings between cubes have mate packages; on the outside walls, an end cap closes each opening that does not have the door or the emergency exit. To add a cube, the crew excavates beside that wall, removes the end cap, sets the new cube by crane and bolts a mate package on both sides of the joint. Today a new cube is $35,500 plus $12,000 for the finish, and the joint takes two mate packages at $4,000 each.
Plan for it on day one
- Leave room on at least one side for future cubes: no septic, well, building or steep slope in the way.
- Place the air and power systems so they can be sized up, or start one tier larger.
- Keep the crane access open on that side.
What to add first
The cubes families most often add are a second bunk room, a bath, a gym, a laundry, or a decontamination cube at the entry. Try each one in the 3D Builder to see the shape and the price change.
Questions
Do the systems need to change when I add a cube?
Often, if the cube adds people. The air, power and water systems are sized by household, so adding sleeping space usually means a larger tier.
Can I add a cube on top?
CUBE Bunkers join side to side. Ask your dealer about stacked layouts for your site.
CUBE Bunker prices are preliminary until engineering for the cube system is complete and are confirmed in writing after a site visit. This guide is general information, not engineering, legal or medical advice. Updated 2026-11-02.