Idea:

I'm planning to purchase a geodesic dome frame for the purpose of making a geodesic dome greenhouse (16ft wide, type: 3V 5/8).

enter image description here

Source: http://geodesicdomes.ca/wp-content/uploads/2009/12/domes-fullsize.jpg

I would cover the geodesic dome frame with clear poly plastic.

I can purchase clear poly plastic in almost any rectangular dimension (either as narrow house wrap or as wider greenhouse poly).


Problem:

When I've researched this sort of setup online, I've found lots of photos of attempted wrapping jobs. Unfortunately, when the poly is wrapped around the dome, it ends up looking as ugly as sin. There ends up being lots of overlap and/or loose areas, which have the added disadvantage of being noisy in wind.

Example:

enter image description here

Source: https://www.instructables.com/id/20-Geodesic-Dome-Greenhouse/

Question:

What method of wrapping a geodesic dome would result in the least amount of overlapping and loose areas?


Note: there are some interesting geodesic dome calculators on this site, however they don't pertain to coverings.

  • 1
    It is geometrically impossible to do this unless the plastic film can shrink or stretch (change shape) around the geodesic frame. – William Hird Sep 13 at 16:08
  • @WilliamHird True, although I can live with some minimal overlapping, etc.. I'm trying to figure out what the least shitty method would be. – Wilson Sep 13 at 16:31
  • Have a look at canvas covering patterns, they're usually pretty efficient – DrBwts Sep 14 at 11:51
up vote 3 down vote accepted

Minimising overlap and loose areas at the same time will be very difficult. It may be possible to source a material that you can ‘shrink wrap’ on, eg using heat, but I don’t have specific pointers there.

Regarding laying a flat sheet, your key aim here should be to have regular overlaps. See tutorials on wrapping circular objects https://youtu.be/dH_gpSfaA6E or industrially wrapped spheres such as old golf balls, or Chocolate Oranges (if you’re from the UK!)

Wrapped Golf Ball

I've been fascinated with geodesic domes since the seventies (last century) and had given some thought to the problem you face. Unfortunately, there is no single-sheet solution to this puzzle.

You may have noted that a geodesic sphere from which the dome is built is constructed of pentagons. You can determine the frequency of a dome by counting from the center of one pentagon to the next the number of struts.

As such, one can cut a sheet of plastic to match the individual pentagons, but it still means that you have to slice a single segment in order to either tape flush (butted) or overlap on the pentagon each sheet. You can get reasonably tight coverage in this manner, but one may consider the taped joints to be unsightly.

The remaining segments that are not pentagons have to be attacked individually. Your selection of a 3v dome gives you a bit of an advantage in that the remaining segments are hexagons, with a center point, with radial struts of the same length, which can be approached in the manner of the pentagon.

Some geodesic designs use individual triangles for construction, which results in duplicated struts at every connection, effectively doubling the material along each path between vertices. This would allow you to pull the plastic into the joint rather than to have to tape or otherwise fasten the plastic to the outside. Think picnic tablecloths draped over the edges, while butting another table against it.

In the case of your EMT based product, this is impractical, especially as it doubles the cost of materials.

You could create an add-on solution by attaching furring strips or similar panels to outline the pentagons and hexagons, using them as clamps to secure the plastic to the EMT. It would still be necessary to slice one sheet per pentagon and hexagon to pull the perimeter tight and secure with the clamping system.

I would hesitate to drill that many holes through what is relatively flimsy EMT and instead would create a hot dog bun or I-beam type of attachment, which would allow for the bolts securing the wood to the EMT to pass alongside the EMT rather than through it.

geodesic bolt block drawing attempt

You could pass the plastic sheet between the top wood block and the EMT or perhaps staple the plastic to the outside of the wood block or to the edges of the block, leaving the top surface of the wood exposed/painted/treated.

One characteristic I recall from my years of reading of construction and pondering geodesic domes is that homespun solutions always had leaking problems!

Silicone caulk/sealer may be desirable to provide additional leak protection.

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