Using Dome Construction for Structural Strength

Group of Earthbag Domes

Based on design, Domes resemble the simple shape of an Egg, which is structurally VERY STRONG.

The construction material you choose, such as wood, metal, or concrete, will dictate the strength of your structure, and can be Fire, Water and Wind resistant.

Monolithic Dome structures, known to be one of the strongest, cannot be destroyed by most natural or man made disasters. They are impervious to Hurricanes and Tornadoes. In cases of fire, even though contents that are flammable will be lost, the basic structure can remain unaffected.

Since a circle contains the most square footage of any design shape, the Dome structure allows for a wide variety of floor plan designs because they need no Interior Support.

This same shape offers Energy Efficiency in the cost of running and heating.

We’ll be covering a wide range of Dome structures. For a detailed look at the variety of Domes and their construction, read our detailed Introduction to Dome Structures.

Image credit: wikipedia

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What are the Structural Benefits of Domes?

Igloo at Night by m prinkeA Dome is a structure built to resemble the hollow upper half of a ball.  The Sphere can take on several round shapes from a half a grapefruit to a bulbous onion, however it’s still  a sphere.  A dome structure is not unlike a dog.  How you ask?  There are poodles, there are Yorkies, there are Bulldogs, and they are all different breeds, but if it scratches fleas, chases cats and goes woof…it’s still a dog.

Domes go back…waaaaay back.  Remains of mammoth tusks/bones used for small dwellings presumed to be domes were dug up by a Ukrainian farmer in 1965 while he was digging in his cellar.  The tusks dated back 15,000 to 20,000 years ago. That’s how far back we are talking about.  Domes are found all over the world made out of a Multitude of Building Materials as mammoth tusks are hard to get a hold of today (kidding)  There’s  an insane number of variations on this theme so one might come to the conclusion it’s a damn clever structure.  Indigenous peoples from all over the world have been building them with whatever local material as available.

Apache Wigwam aka Wickiup, image by Edward Curtis

The Native Americans had Wigwams made from branches and hides, while the Inuit made Igloos from blocks of snow, and the Himba people of Namibia made a similar igloo shape out of wattle and daub as they were desert dwellers.  Clearly the engineering works so word got around.

I did warn you that there is an insane number of domes so I whittled them down to something manageable just to give you a taste test.  There is the…

Corbel Dome:

Generic stone arch on left vs Corbel Arch on right, image by wikimediaCorbel Dome Atreus, image by wikipediaCorbel Dome stone interior, image by wikipedia

-which consists of many horizontal layers that slightly lean inwards towards the center until finally meeting up at the top.

Onion Dome:

Shiny Onion Domes on a Russian Orthodox Church, image by Horia VarlanConverted Windmill with Onion Dome, image by Ian PatersonWhitestone Blue Onion Dome, image by wikimedia

- which looks just the way it sounds, like a bulbous onion tapering smoothly to a point. (think the Taj Mahal or Russian Orthodox churches).  I am told that I was baptized in a Russian Orthodox church, but honestly all I can remember about the joint was the smell of the incense the priest was swinging around….so not sexy.

Oval Domes:

Oval Dome Vicoforte, Image by wikimediaOval Dome Interior of Saint Peter's Basilica, image by wikimedia

- considered to be a Baroque period style. The term comes from the Latin ‘Ovum’ meaning egg.

Parabolic Dome:

Parabolic Dome, image by phileole

- used widely in ancient times before Hybrids were created.  Unique in that the bending stress is zero (however) if a load is applied directly to the apex of the dome the stress becomes infinite (that so doesn’t sound good) so the tops of the dome had to be stiffened or its shape modified to avoid this potential engineering disaster.  No wonder it went out of fashion.

Polygonal Dome:

A Polygonal Dome, image by wikimediaPolygonal Dome on the Florence Cathedral, image by wikimediaPolygonal Dome on top of Thomas Jefferson's Monticello, image by wikimedia

- these are domes which maintain a Polygonal shape, and here’s a neat bit of trivia: Thomas Jefferson the 3rd U.S. President, installed one above the West front of his plantation house called Monticello.

Sail Dome:

Diagram of a Sail Dome, image by wikimediaDiagram of a Sail Dome aka Pendentive Dome, image by wikimedia

- these domes resemble a Sail pinned down by four corners of a perfect square giving the impression of a sail billowing upward.

Saucer dome:

Saucer Dome on the Louisiana Superdome, image by WikimediaSaucer Dome Greenhouse at the Huntington Library, image by Rennett Stowe

-these do look abit like someone took a saucer of milk (without the milk) and placed the top dome part over a round base. Many of the largest domes built are of this shape.

Umbrella Dome:

Umbrella Dome over a Garden, image by luvjnxUmbrella Dome interior of Santa Croce, image by wikimediaUmbrella Dome sunburst over a garden, image by luvjnx

- looks like an umbrella.  The dome is segmented by ribs that radiate from the center out and the material in between transfers any downward force. The central dome of St. Peter’s Basilica uses this method.

For the sake of not turning you stark raving mad I will focus now on two of the more popular residential, and dare I say sustainable domes around….Geodesics and Monolithic Domes.

Geodesic Dome:

Panoramic view of the Geodesic Dome structures of Eden Project, image by wikipedia

- is a closed structure; a sphere made up of a Network of Circles lying on the surface of the sphere. (think soccer ball) The circles intersect forming triangular shapes that distributes the stress across the entire structure in an omni-triangulated manner.  Interestingly enough Geodesic designs didn’t make it on the scene until after WWI, and were made popular by American author, architect, and visionary Buckminster Fuller. Today in Canada we can see an example of that at the Montreal Biosphere.

Geodesic Dome Epcot image by WikipediaGeodesics are of particular interest in that they share the tensile force evenly throughout the structure.  This is incredible engineering when say an earthquake hits.  No matter which direction the shearing force comes from the structure seems to weeble and wooble but not fall down.

Take a look at the video footage of these tests conducted here in Vancouver, Canada at UBC:  http://www.youtube.com/watch?v=PE4VbLB0csA

Middle Earth Home website

Monolithic Dome:

Dome Diva Cindy Johnson in front of her Sculptural Monolithic Dome, image by Monica Holy

- is a sphere cast in one piece over a form.  My very forward thinking Aquarian friend Cindy Lou Who (from a long line in Whoville) has built her very own concrete/foam dome (in the Okanogan area of B.C.).

Steel Framework for Dome Diva's Monolithic Dome, image by Cindy JohnsonExterior of Steel Framework for Dome Diva's Monolithic Dome, image by Cindy Johnson

You start with a Steel Framework wrapped with a steel mesh like chicken wire that is tied into place with wire ties.

Coat of Sprayed Cement over Steel Framework on Dome Diva's Monolithic Dome, image by Cindy JohnsonFinished Coat of Sprayed Cement over Steel Framework on Dome Diva's Monolithic Dome, image by Cindy Johnson

The whole exterior surface gets a Coat of Polyurethane Foam. The Foam has a 10 mm Skin of Elastomeric  Paint. It is then Bermed, and finished off with 3 Coats of Ceramic Insular Paint for added Thermal Mass and Waterproofing.  The inside is Concrete Parget (a cement mixture such as Plaster or Roughcast, used to coat walls, line Chimneys, or waterproof  outer walls), over Shotcrete (A concrete mixture that is sprayed from a special gun over steel reinforcements in light construction).  Her process was intensive as Cindy believes in overkill.  The beauty of overkill Cindy Lou claims is that after berming it she insists she can heat the place practically by lighting a candle.  Naturally cool in summer and cozy in winter this is a dome that can weather some pretty serious storms.

Exterior Window of a Structural Monolithic Dome by Dome Diva, image by Monica HolyA Sculptural Monolithic Dome, by Dome Diva, image by Monica Holy

Not to be too dramatic here but FEMA rates them as “near-absolute protection” from F5 Tornadoes and Category 5 Hurricanes. Recently, a number of monolithic domes constructed using MDI ( Monolithic Dome Institute ) techniques have survived major disasters.  In fact in 2003 one such domed government building in Bagdad, formerly a part of Saddam Hussein’s regime, was hit by a (2,300 kg). bomb, and apart from the hole made by the entry of the bomb, it remained structurally sound.  Now THAT’S what I’m talking about!

Check out Cindy’s Dome Diva Blog for more information:

http://www.domediva.com/

Other Examples of Monolithic domes to survive catastrophes:

Several monolithic domes in Florida survived direct hits by Hurricane Katrina in 2005.

Several monolithic domes were in the path of the 2005 and 2006 wildfires in Oklahoma and Texas, and survived with only slight charring of the exterior foam insulation.

The demolition of Ream’s Turtle also demonstrated the durability of the monolithic dome structure. A wrecking ball demolished a strip several feet wide around the perimeter of the structure, without a collapse. When a doorway on one side was pulled down, the dome finally tipped over, and collapsed.

Thumbs up image for Middle Earth Home, photo by Monica Holy

Advantages of Domes:

  • A dome can be thought of as an arch which has been rotated on its central axis. thus domes, like arches, have a great deal of structural strength when properly built and can span large open spaces without interior supports.
  • A sphere encloses the greatest volume for the least surface area.
  • The monolithic dome is ridiculously Energy Efficient. The spherical sections of the dome offer minimal surface area for the volume they contain, so there is less surface for heat transfer with the outside air. The one piece construction of the monolithic dome also eliminates many of the seams through which air can leak, though this is mitigated to some degree in residential domes by the addition of multiple doors and windows. By placing the insulating foam on the outside of the concrete shell, the concrete acts as a heat sink inside the building, reducing interior temperature fluctuations far more than the traditional home’s insulation.
  • FEMA rates them as “near-absolute protection” from F5 tornadoes and Category 5 Hurricanes and recently, a number of monolithic domes constructed using MDI ( Monolithic Dome Institute ) techniques have survived major disasters.
  • If you like options there are as many styles and looks of domes as a person could hope to choose from.
  • Very unique, very individual.
  • If bermed a monolithic dome can take on a living roof and blend into its natural environment.
  • Can build a monolithic dome for practically the same cost as a regular post and beam.  Think a post and beam is likely survive a natural disaster?
  • Canadian wooden domes would say they are cheaper than regular construction as an unfinished 26 foot diameter sphere goes for only $25,000. and can be assembled in six hours.
  • Yeah you read that right.  This particular dome gets assembled in 6 hours which makes it Ideal for Emergency and Disaster Relief Shelters. (you know…if the in-laws drop in on you from out of town).
  • Where Canadian wooden domes is concerned the wood framing is made out of 14 inch trim ends from saw mills or waste wood left behind from making construction lumber. (probably what keeps the cost way down)

Thumbs down image for Middle Earth Home review, image by Monica Holy

Disadvantages of Domes:

  • Like the coffee scene from Moscow on the Hudson, a laymen could have a nervous breakdown in aisle three trying to sift through the multitude of choices out there.
  • The round shape of the house makes it difficult to conform to certain code requirements for say placement of sewer vents or chimneys depending on your postal code.
  • Windows conforming to code can cost more than windows in conventional builds.
  • Professional wiring/tradesmen costs more to accomidate increased labour time.
  • Depending on how the interior space is interpreted there may be a privacy issue.
  • Sounds, smells, and reflected light are experienced throughout the entire structure.
  • Room is round.  Appliances are rectangular.  It will take a great imagination or an interior designer to figure the space out.
  • Of course you can always have custom made rounded furniture made (couch) but that’s gonna be expensive.
  • Former Buckminster Fuller’s student J. Baldwin insists a properly designed and built geodesic will not leak, but what if it’s not properly designed or built?
  • The techniques used in monolithic dome construction are very different from normal construction methods, so only specially trained construction crews are suited for building a dome using the modern techniques.(unless your name of course is Cindy Lou…not your average bear from Whoville).
  • The monolithic dome’s lack of seams may make it too well sealed; dehumidifiers are required in all but the driest.
  • Do all the neighbours on your block appreciate your radically different looking home?
  • Radically different usually translates into difficult to get permits and…
  • Radically different also means difficult resale on the real estate market.
  • Building permits may be difficult to obtain if local officials are not familiar with the monolithic dome.
  • Resale of a monolithic dome home may be difficult because of its unconventional appearance.

Dome Sites of Interest:

How to build a Monolithic Dome:

http://www.monolithic.com/stories/how-to-build-a-monolithic-dome

Domes for Sale(Real Estate):

http://www.naturalspacesdomes.com/domes_for_sale.htm

Monolithic Dome Institute:

http://www.monolithic.com/topics/institute

Eco Dome Super Adobe/Sandbag technology:

http://calearth.org/building-designs/eco-dome.html

Personal Biodomes as Homes:

http://www.intlistings.com/articles/2008/25-incredible-personal-biodomes/

Books:

How to Build the Strongest, Most Fireproof, Tornado and Earthquake-resistant Concrete Dome House by Jan Hornas

Earthbag Building by Kaki K. Hunter

Monolithic Newsletter:

The Roundup The Roundup- Monolithic Newsletter
The Roundup — presenting the latest Monolithic news – May 26, 2010

Youtube:

Seismic testing done at UBC/Canadian Wooden homes:

http://www.youtube.com/watch?v=PE4VbLB0csA

Manufacturers and Builders:

Monolithic  Institutes’ dome builders worldwide directory:

http://www.monolithic.com/stories/builders-list

Canadian Monolithic Dome builders:

Evans Shotcrete Domes, Inc.

Box Office 214,Cold Lake, AB T9M 1P1

Office 780/594-6398, Cell 780/207-7575

Email: elizevans@xplornet.com

Toby Neuendorf EcoDome

110th Street, Edmonton, AB, T5K 1H8

Office 780/352-4190

Cell 780/362-1274 cell

Email: toby@ecodome.ca

Robert R. Phillips, P. Eng Canadian Dome Industries, Ltd. 306/229-1650 814 –

50th Street East , SK S7K 0X6 Canada

phillipsr@canadiandome.ca Saskatoon

Canadian Wooden Domes (aka Altus Engineering Ltd)

Designs, manufactures, sells and constructs Geodesic structures, operating out of Vancouver, British Columbia.
http://www.curvedbydesign.ca/

B.C. Geodesic Dome Builder: http://www.domes.ca/

Dome Homes Directory of Builders: http://www.ecobusinesslinks.com/dome_homes.htm

Image Credits: m.prinkewikipedia, Dome Diva, Monica Holy

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