[midnight-gamer]

I would like opinions about a odd style home design. The claim I have heard is that the shape helps save energy, and uses fewer materials. http://domehome.com/productinfo.html
The website looked so curious I just had to put it out here for your thoughts.

[cynthia]

Domes are strong and economical-even when built with earth. It is an old design. Passive solar should be considered during any housing project.
My favorite site: http://www.deatech.com/natural/
Alas! I did not answer your original question. Still, I plug my favorite building mediums. Good luck with your dome-based pursuits.
cynthia

[gg3]

Yo MidnightGamer: the answer is, domes made of panels in that manner, are susceptible to water leakage at the joints, which will be subject to expansion/contraction throughout the life of the building.

Ideally what you want is a single surface covering the entire dome.

For this, you want ferrocement construction: stucco over wire mesh. Incredibly strong per unit weight of materials used. If it's placed monolithically there are no seams to leak. Keyword serch "ferrocement dome" and read up.

As for curvy walls inside one of these things, you stil have interor a partition walls with linear surfaces for conventional furniture, and the the ability to custom-build built-ins along the curved walls.

[midnight-gamer]

GG3, I have googled "ferrocement dome" and I must say, I like what I have seen thus far. I am sure everyone here knows of "The Empire Strikes Back". Ferrocement domes looked a little like Yoda's house in the swamp.

[TommyJefferson]

The claim I have heard is that the shape helps save energy, and uses fewer materials.

That claim is false.

Fitting right angled building materials into curved spaces generates a lot of waste.

[WisJim]

I have friends who built a ferrocement dome, and it has been an expensive disaster, in my opinion. They are living in it ,and continuing to work on it, but for the amount of m oney and problems they have had, they could have built and finished a more conventional building and ended up with space that is easier to utilize and more comfortable, and not be over their heads in debt.

I have know folks who have built and lived in geodesic domes, since the late 1960s, and they have either moved out, used them as storage or barns after building a "regular" house, or added lots of rooms with square corners and straight walls to get some usable "normal" living spaces.

I think that a dome would make a great greenhouse, with big trees in the center, and small stuff at the edges, allowing use of more of the space. I wouldn't want to live in one.

[thuja]

Back in the eraly 90's I lived in a dome on a 40 acre spread out in the woods with 12 other freaks. The land (known as Delphi) had 2 geodesic domes, a converted chicken shack, a 4 story tree house, a couple more outbuildings and a old turn of the century farmhouse that was falling apart- all without indoor toilets.

The dome I lived in was up on a platform and had a canvas mesh cover- sort of like living in a big tent. I'd make a fire in a big old pot bellied stove and get really warm, and then when the fire died down, I'd get really cold- fast! Living out in the damp woods near Olympia, the dome started to develop serious internal and external mold problems...in fact I renamed my domicile "The Mold Machine".

The best part about it was it had a retractable skylight made of visquene. There was a platform that the skylight sat on and you could pop the top and sit up there, smoke a bowl and commune with the pileated woodpeckers and the forest spirits. The problem came during the rainy season (October to May). The skylight had a leak problem and my bed was built as a loft just underneath the skylight.

I remember one night falling to sleep just as a storm rolled in. At first, little drops of water would splash gently next to my pillow. As the storm got fiercer, the drops turned into a tiny trickle. I remember trying to plug the gap with some sort of cloth and inadvertently moving the skylight slightly. The visqueen had sagged with the weight of the accumulated rain and after I tried to adjust it, the entire load of water swished to the gap and poured down on my head in a stream.

Ah the geodesic dome...Good times!

[Aimrehtopyh]

How about "steel span" buildings. I've been intrigued by them for quite a while and I've loved the quonset hut look since I was a kid. They aren't really domes but are definitely more dome-like that the stick-built $#!+ shacks that pass for houses these days.

They're mostly used for storage sheds and such but has anybody actually visited one that was used as a residence?

[yesplease]

I've seen a couple of those around here. Nice, but a bit pricey imle. I really like the look and hopefully, construction costs of rammed earth. I'd rather go with more labor and less money than the other way around.

[gg3]

$10 - $15 per square foot of enclosed space is pretty darn good, though of course it doesn't include basement/foundation, interior partition walls, insulation, plumbing, electrical/telecom, etc. etc. etc.

The design is inherently strong, since it's a continuous arch.

I also love the look of the traditional quonset huts. Something very basic & purposive, clean geometry, no frills, looks like it emerged from the earth, it's not pretentious, it's practical.... etc...

The newer variations with the more conventional profiles (quasi rectangular when seen from the front) don't do it for me aesthetically; they look like an attempt to make it into something it wasn't originally. Also the newer designs look very accordion-like and I wonder how that would perform acoustically in the wind.

I would consider building & living in one of these. In fact it might be the ideal solution to the question of how to get an exterior shell up quickly and have the freedom to do the interior build-out over time.

Question is, what to do about an exterior coating that would be waterproof. Stucco over some kind of plastic comes to mind, and would provide good thermal mass & fire resistance, not to mention resistance to various forms of impact damage e.g. falling tree branches, projectiles, whatever. Anyone have any other suggestions in this department?

I think I'm going to bring this up with my group and see what they say...

[TommyJefferson]

Anyone have any other suggestions in this department?

I did a lot of research on domes a few years ago and determined ferrocement over a wire/rebar frame was the best.

I reusable bladder is inflated in the structure to hold the sprayed cement until it hardens.

Just as with building a computer, using standardized, mass-produced components is cheaper due to economies of scale than trying to build something weird that achieves the same functionality.

Basically, domes are a dead-end when it comes to cost-effective housing. But don't take my word for it. Run the numbers and do your own analysis.

[midnight-gamer]

Thanks for the tips. I'll agree with Tommy Jefferson that dome houses seem a little sketchy. The idea was a new one to me and I wanted to look into, and present it to the forum with an open mind.

[gg3]

Inflatable bladders and shotcrete (sprayed-on concrete) are fairly hightech methods, beyond the reach of your average sustainable community group.

However, similar results can be obtained with a properly organized crew of large enough size. The key here is a) lots of scaffolding, and b) mix & place the concrete quickly enough to get a monolithic structure. This takes a large crew working a long day. How large depends on the size of the dome.

[Aimrehtopyh]

...newer designs look very accordion-like and I wonder how that would perform acoustically in the wind....an exterior coating that would be waterproof.

If you're referring to steel span structures here I don't think that any exterior coating would be necessary or even advisable. The ones that I've looked into are made of a galvanized steel that won't show "red rust" for upwards of 25 years. Additional layers might only trap moisture against the steel, shortening its lifepan. Paint might make it last longer.

I think that the "accordion" look is to stiffen the structure to where no internal supports are necessary. I think old smooth-sided quonset huts had wooden or steel frames.

[strider3700]

I'm pretty sure that you won't get much less expensive then a square building built with plaster covered sandbags acting as the walls.

Round is cool and can be strong but will be expensive.

[azreal60]

It entirely depends on what your using as your building materials. This post is slightly offtopic, as I'm not talking about domes. I personally always thought domes where a cool idea, but after actually studying them, I far prefer Cylinders as a home building shape.

I very much like them because they make maximum useage of a central radient heat source, and are a very strong structure. In addition, they don't make the assumption that people will somehow come up with very inventive ways to make use of living space that is varyingly smaller and bigger depending on the height your at.

[tsakach]

If your property is located anywhere near an earthquake fault zone and you are considering "earth" architecture, I would really be concerned with the possibility of the structure collapsing during a major earthquake.

Some well-meaning organizations sell plans for earthbag architecture that are claimed to be "earthquake safe". These structures are constructed from a concrete-like mixture of earth and portland cement, which is placed into bags with layers of barbed wires between the rows of bags.

While the barbed wire provides structural reinforcement to support the weight of the structure, no vertical structural reinforcement exists between the bag layers. The lack of vertical structural reinforcement could cause separation to occur between the bag layers during an earthquake, and may result in all or part of the structure to come crashing down on the occupants.

After submitting earth architecture plans to the building department, in many cases the owner/builders have received comments from the engineering review process, such as "provide vertical connections between bag layers." While it is possible to make these structures reasonably "earthquake safe", it only adds to the cost.

One assumption people make is that earth architecture is inexpensive to build compared to conventional construction. Actual experience has shown that only the cost of building materials is less. These structures take a lot of time and effort to build, and the cost of labor is many times more expensive per square foot compared to conventional construction. If you factor in additional costs for modifications required by the building department to make these structures reasonably earthquake safe, these structures wind up costing 3-4 times more per square foot than conventional construction.

One compromise solution I have seen is to use the earthbag technique for the foundation and walls up to a few feet, and attach a yurt or framed dome structure to the earthbag foundation. I would feel much more comfortable with this arrangement, having a lighter structure above.

[yesplease]

Some earth bag construction has been approved for use, but CA's earthquake regulations may be lax. Using a Yurt or framed dome definitely seems like the best of both worlds, so long as the top of the earthen walls are reinforced with beams going across.

Superadobe Technology, U.S. patent #5,934,027, has been tested on individual dome and vaults (1993-1996) for the City of Hesperia, California, Building and Safety Department, in consultation with I.C.B.O. These structures passed the California required codes.

[tsakach]

Some earth bag construction has been approved for use, but CA's earthquake regulations may be lax. Using a Yurt or framed dome definitely seems like the best of both worlds, so long as the top of the earthen walls are reinforced with beams going across.

Superadobe Technology, U.S. patent #5,934,027, has been tested on individual dome and vaults (1993-1996) for the City of Hesperia, California, Building and Safety Department, in consultation with I.C.B.O. These structures passed the California required codes.

Yes, I happen to have a copy of the complete engineering review process for this, where the City of Hesperia granted a building permit for superadobe. The permit approved by the City of Hesperia was for a non-residential structure, the Hesperia Lakes Nature Center and Museum. This structure was actually built and later bulldozed with the explaination given that shoddy construction was to blame.

During the review process, the engineer hired by CalEarth made the following statement regarding vertical ground movement:

Upward vertical motion in a seismic event will not create a problem. The mass of the structure reduces as we approach the top and the continuous wall provides a large amount of surface area to distribute any dynamic stresses induced by a vertical rising motion. Downward vertical motion in a seismic event should also not create a problem since the shear mass of the structure would make vertical seperation virtually impossible

That's it. There are no references or calculations to support the claims made by this engineer that "the shear mass of the structure would make vertical separation virtually impossible." In addition this statement was not challenged by the Hesperia building department. I would not want to bet the lives of my family and myself on unsupported statements such as this.

The structures were required to undergo dynamic load testing, where asymetric horizontal stresses were applied to the structure. These tests passed with no problems. However, no testing or simulations have been performed on these structures where vertical seismic motion is involved. This type of motion is present to varying degrees in almost all earthquakes. As a general rule vertical motion is defined to be 2/3 of the horizontal motion. But depending on characteristics specific to the site, such as terrain or soil, the vertical ground motion can actually be greater than the horizontal motion.

Other building departments are more cautious about granting approval for these structures. For instance, when submitting plans for a superadobe structure to the San Bernadino County building department, the following comment was received from the engineering review process:

Provide positive connection between the sand bags and between each layer of sand bags per CBC section 161633.2.5. The bar wires between the bags are not approved connectors.

They also wanted a study on the "Known Active Fault Near-Source Zones", and soil profile, which indicates that they are looking for the potential vertical ground motion at the site.

A superadobe structure was built on the Pomona College campus in the county of Los Angeles. The county required welded wire mesh to be installed on both the inside and outside of the structure, and shotcrete applied over the wire mesh, which increased the expense of building the structure.

So, while superadobe has passed the "required California codes" in some cases, it is still up to the owner/builder to decide if they are comfortable with being a guinea pig. I decided to pass on this opportunity and stick with something that has been proven over the test of time.