The Cave

We’re embarking on creating the eight supporting columns for The Cave and are looking for advice & recommendations for the best way to make them.  We’re actively exploring several options, but prefer not to re-invent the wheel and would very much appreciate input from anyone with relevant experience.  (The Space Virgins camp and Connexus Cathedral are a couple projects that come to mind as projects that did well with columns.)  If you think you can help out, a more detailed description of the design problem is below.

Thanks,
Chassy

The renderings at the bottom of the page show the basic structure that we’re working on.  The eight columns support an open-roof gazebo approximately 25′ across and 14′ tall.  The upper portion will be constructed from plywood & the whole thing will be reinforced & tied down to resist major windstorms.  The finished version will include a frieze of scenes from American folklore around the top, fire pit & seating in the center and projection screens that will fill the space between the pillars.

The basic requirements for the 8 columns themselves are:

• 10′ tall x 14-17″ diameter.
• Fluted & tapered form is preferred, but not necessary.
• Hollow center to contain the structural timber that will support the upper portion of the structure.
• Solid to the touch.  Someone should be able to lean against a column without feeling it give.
• Weathered stone look.  The structure is meant to look like and old abandoned marble gazebo.

We’re already looking at a few options for the columns.  They’re all a tradeoff between cost, labor and environmental friendliness.  Again, we’d love to hear from anyone who has had experience with these techniques.

• Premade Foam Columns
  Premade foam columns seem to be the simplest.  However, the two drawbacks are that they are the most expensive and least environmentally friendly options.
• Casting Columns Ourselves
  We’re currently doing small scale tests with lightweight concrete mixes - hypertufa (cement, perlite and spagnum moss) and papercrete (cement & paper pulp.)  The full scale columns would be cast with 3″ thick chickenwire reinforced walls.  Of the available options, this is the most labor intensive, but will probably have the best weathered stone look.
• PVC Pipe
  PVC pipe would be very easy to use for the columns themselves.  We would still need to cast the capital and plinth, but that would be simpler than casting the entire column.
• Stucco
  The final option is to stucco over a cardboard and wire mesh form.

Again, if you’ve had experience with any of these techiques and have advice on what to do or avoid, we’d love to hear from you.  Likewise if there are other options we should be examining.
Fluted Tapered Columns 10′ tall x 17″ diameter

Straight Columns  10′ tall x 15″ diameter

The Cave was funded!