DOME BUILDING

One of the reasons I have always liked the idea of dome building is the extreme efficiency in the use of materials, and the annoyance in the fact that so many building methods are so remarkably old without much improvement. The main expense of a house is at least in part due to the need for a very strong foundation to support it, it is essentially made of reasonably strong wood, but its just hinged together, like many doors, except at angles that give some rigidity. As a result if you make a stronger house to resist an earthquake, it becomes so much heavier, that you may gain less advantage than you hoped. Despite how strong wood is in relation to cost, you can still end up spending a fortune to protect it from water, that would do foam or plastic no harm at all , and cement only little harm. Save money on the cheaper material and spend a fortune on vinyl siding that gives little structural advantage. However one of my main hopes for domes is still one of a cheaper shelter for low-income people and or just a much safer one for those that can afford better ones. Easy to see how these can be safer I once made guess estimates how well a thick walled ferrocement dome could withstand a nearby nuclear blast and it looked like it could easily be just outside the fireball. Provided not hit with heavy projectiles, not to mention how good they can be for underground or underwater, and still be cheaper than a regular house in materials for the same area.

You will have notice I mention little on the type of dome used for greenhouses, in part because almost anything cheap that you could use to cover them with will break down in sunlight or rot, along with having no insulation value. When using expensive materials like this, you may as well use foam and get the advantage of its insulation benefits, but it still doesn’t hurt to look at acrylics because they are so weather resistant. But if you want one of these types of domes, just use the same lengths as used to make the foam triangles that are listed below. Modestly durable coverings, such as special UV resistant polyurethane, is something like .35 $US a square foot and is guaranteed for ten years but greenhouse polyethylene is guaranteed for 3 years. Seen from my perspective its guaranteed to start going bad after that time and guaranteed to degrade but remain usable before then. For greenhouses you may have no choice .A dream dome would be one made with transparent airogell panels that are both translucent to let sunlight in but with the insulation value of good insulation, with the ground or pond bellow to store solar heat. If cost is no object for flexible coverings look into translucent glass reinforced Teflon, but if you use transparent acrylic panels, that are truly durable with good resistance to sunlight degradation. You probably don’t need the

Framework and can use a similar construction method as used for the foam domes described below. You an buy an acrylic based fiberglass type resin that can be used with fiberglass, but you need to look for it as a special resin and is available clear and colorless, that means any durable pigments added will give a pure color and not lose its color. One place that sells one type of resin is Castolite

Fire can also be something you can avoid with all ferocement domes but after building them I came to realize its so much easier to just make the foam dome and then a cement one over it is much easear

So that it may still be easier to just fireproof the inside after building in foam also in part because you still have to insulate. This is why I suggest adding stainless steal wire from the cement used to bond the foam to use as a hanging surface for whatever finishing you may now or in the future decide to add. On my dome I have used ordinary fiberglass insulation that is tied on with the wire and that I later covered with aluminum foil to give a space ship type look. I d really like to get to use the stuff used to cover actual space satellites, but if you got lots of money you might take a look at some of the Teflon film or the type reinforced with fiberglass used for commercial environments. The military has a kevlar reinforced Teflon in some types of tents that I have read about

As is the nature of this booklet it is a guide to let you chose what you want in a dome and how much to spend or experiment with. You may find it most interesting about the tests I have done on the strengths of materials based on weight where volumes dose not mater. You will see how similar cheap bead board foam is compared to plywood in relation to strength to weight and note how sandwich foam construction actually adds about as much extra weight as it dose strength. But I do warn you these tests are done by my own home made equipment, in my best effort to be honest and reasonably accurate

They are

by no means the best tests that could be done, so I have included more information on how I did these tests so you may repeat, improve on or extend on them. Also note that the wood was of unknown moisture content and were not the best samples to use, I will try to update this on my web page if possible

All bead foams are the 1-LB cubic foot, its about R 3.5

All SM is the high density structural Styrofoam of 2 LB per cubic foot, its about R5

All samples are 30 cm long in its tested area, except where noted otherwise

Amount of deflection when broke may have been more difficult to be as accurate on so expect even less accuracy on already approximate data

Dimensions are in inches

Weights are in grams

MY TABLE OF ENDURANCE FOR VARIOUS MATERIALS
 

			amount of weight to produce bending to				load when broke or permanent deformed	amount of deflection when broke
description	dimensions	weight	1/16	2/16	3/16	4/16
bead board	1.5x2x30cm	12g	500g			1.6kg	3kg300g	nearly 1 inch
bead board	3x2x30cm	24g	4.5kg				12kg
SM. foam plain	1.5x2x30cm	20g	1.5kg		4kg	6kg	8.8kg	over3/4 inch
SM foam 10 ounce epoxy fiberglass cloth both sides	1.5x2x30cm	55g					19.5kg	+or-1/16 inch
bead board plus 10 ounce epoxy fiberglass both sides	1.5x2x30cm	40g	13.5kg				16.5kg	3/16
bead board cement on load side1mm thick+ plus ¾ inch wide 6 ounce fiberglass on bottom	1.5x2 x30cm	49g					over 17kg but 5 extra kg resulted in sudden collapse	1/16
bead board + ¼ inch of high density foam on both sides ,estimated extra weight 1/3 more =16g	1.5x2x30cm	16g but glue added to weight to give 28g	1.3kg	3.2kg		4.5kg	7kg slowly to +or- ,½ minute to collapse	nearly 1 inch
plywood grain at greatest strength lengthwise	1/8x2x30cm	56g	600g			3.5kg	11/16 at 6.5kg total deformation at 10 kg
plywood grain at greatest lengthwise strength older sample was used	1/4x2 x30cm	81g	7.5kg		12.5kg		18.5kg
bead board epoxy treated paper both sides	30cm	1.5x2	26or27g	6kg			8kg
bead board paper both sides no treatment	30cm	1.5x2	12g		2kg		3kg
wooden rake handle	60cm	24mm 15/16	125g				80-85kg	under 1 inch
wooden broom sticks	60cm	round 21 mm or 13/16	125g				61 kg	over 1 inch
aluminum tubing from lawn chair	60cm	1 inch + or - 1mm thick wall	100g				over 50 kg next test 61 kg	may have =1/2 inch before permanent

The method I used to do these test is very simple, for example use an old bucket or something similar that you have measured the weight of and added extra weight to make it some easy to keep track of weight like 2kg. Measure the samples to test and try to hold to some same standards like all at 2 inch diameter and 30 cm long but just the thickness being changed or what have you , to make comparisons easy and just decide what to use to support the ends of the samples , and weights to use and etc. But when testing foam and soft materials you may need to use soft flexible materials to spread out the load slightly to prevent cutting into the specimens from the bucket handle and use it on all the tests to be consistent

HOW MUCH MATERIALS YOU MIGHT NEED

This is intended to help as an approximation and I do mean approximation to speed up any guesswork on what a dome might cost and its also made on the assumption that you waste very little. It is possible because scrap peace's can be made into larger pieces, this is what I did.

All my - means the remainder is cubic feet
 
 

Dome diameter	cubic ft remainder is extra cubic feet	cubic yardsremainder is extra cubic feet	4x8 remainder is extra cubic feet
5 ft	37	4-1	1-5
7.5	80	8-8	2-16
10	148	16-4	4-20
12.5	233	25-8	7-9
15	323	35-8	10-3
20	580	64-4	18-4

SOME GENERAL RULES ON STRENGTHS OF MATERIALS

When dealing with sandwich foam construction where you double the thickness but keep the layers of fiberglass and density of foam the same, you get nearly 4 times the strength at about 8 times the stiffness for the same length of area covered , as in ultra light wings , of course you can't just add extra thickness to a wing as such . Note that the extra foam adds very little extra weight relative to the extra strength.

A column 1/2 the length of another is 4 times more resistant to buckling

A column with both ends embedded in a solid structure is 8 times more resistant to buckling than a column with only one end embedded. One end embedded is called a cantilever column
 If you were to apply this principle to all of the individual components of even a regular wooden house it would become considerably stronger . Nails do not usually do a good job of holding such things as beams rigidly at their ends and is in some ways is more like attaching everything with loosely attached hinges.

Concrete often has its reinforcement along its bottom if it is to carry a load on its top. This is because concrete has little tensile strength and the reinforcement adds this.

Note that for the most part just the surfaces of a beam carry both the tensile and compressive loads. Stand on a beam and the surface is compressed and its bottom layer is stretched. The middle mostly just keeps the two layers apart, and that is why honycone as used to keep layers apart in aircraft wings, as well as why foam is used and why tubing is so good at getting the same material to carry greater loads
 
 

FOOD FOR THOUGHT RELATING TO STRENGTHS OF MATERIALS

It may become obvious that because foam is so thick it gains a lot of strength just from that effect alone. But what can be done to make full advantage of this without adding much weight , it may be much better to add a fish net type fiberglass reinforcement, to foam. This is because foam has a very low tensile strength and stiffness so it should take very little in fiberglass strands to equal the strength of one whole extra layer of foam , in effect making it behave like its twice as thick. Providing it doesn't cut into the foam to much .You may notice that the cost of fiberglass cloth doesn't change as much with thickness as one would hope, resulting in very thin fiberglass cloth being nearly as expensive or become even more expensive for the same coverage than the much thicker and heavier cloth . This tends to sagest that the use the heavier cloths to cover the entire foam surface , may only be practical with the thicker foams. Fiberglass strands however can be used without this concern allowing you to only use a few ounces or grams of it per square yard and it remains cheap for the same weight. Regardless of how much area is or is not covered.

I recommend that if you try this, try to get the strands used to make wicker furniture, at least the type I saw had no binders that were intended to soften with fiberglass resin. You cannot use fiberglass resin on polystyrene foam, as it will melt into a liquid. Epoxy resins will not, you can use fiberglass resin on polyurethane foam but be aware that polyurethane foam is less moisture resistant but some have about a R6 per inch insulation value
 
 

Of course a lot is said on Form Resistant structures its what an egg is as well as saddle shaped roofs and lots of others as well. Ferro cement domes, that is domes made with iron mesh reinforcement are usually not over 3/4 inch thick due to the strength advantages of using curved surfaces to attain strength . Also these domes often usually are recommended to use at lest 4 layers of 1 inch chicken wire as the mesh. Real performance of curved surfaces is also demonstrated by using them in submarine hulls and the best of these is spherical as in the deeper going research subs. Most military subs use cylindrical hulls and can’t go down nearly as deep as a result. A clear acrylic sphere about 5 feet diameter and 5 inches thick has been recommended to go to 2000 ft. Only about 200 ft down is recommended for the cylindrical type

MORE TIPS ON MATERIALS

You should also note the cost of breadboard foam as insulation over fiberglass as insulation I think its about 5 times more expensive to use the foam to insulate.But my estimates may be off and not every place prices it the same also the fact that fiberglass sound proofs fairly well, but closed cell foam conducts sound well. So because of this it might be interesting for someone to experiment using a thicker foam wall with a foam honeycomb with its spaces filled with fiberglass insulation to further reduce cost, increase strength, and soundproof. Don't forget the fiberglass strands to further strengthen the foam

I have found that old fiberglass curtains the type that are fireproof and also look a little like very lightweight fiberglass, work reasonably well in reinforcing epoxy, you cannot get any respectable results with fiberglass resins on this type of material. Remember epoxy even the liquid stuff used in the boat building industry is a glue, but fiberglass resin is much less so, the fiberglass cloths are usually treated to enhance the bond with it. Ever sense I have found out about this I have used a lot of it in part because despite the grater cost of epoxy I save so much on the cloth that its justified and epoxy is almost always better or is the only thing I can use. However this recycled cloth may not be recommended for high performance applications. Not all uses require high performance.

It might be interesting to do some experiments using old cloth and house paint as glue to make a cheap plywood substitute because you can get the extra strength advantage of multiple curved surfaces to make lighter and cheaper domes and use recycled material, my experiments were just preliminary

You can also use old house paint to glue paper to the surface of bead board foam and I did this a few times, then I finished with treating the paper with epoxy to water proof it. This is an advantage, because despite that house paints I used, contain water, they become water insoluble after drying. You can try other approaches and materials with this such as bonding old fiberglass curtains or cloth to the foam surface as both finish and reinforcement etc.

Old fiberglass curtains with pure cement may not have the best bond but may still serve to reinforce and fire retard foams. Point to try is that sometimes burning the old fiberglass curtains may remove the organic layers to help enable its fibers to better bond with cement but remember its easy to lose most of the strength by this. HoweverI have seen samples that were still strong enough to use even if burned. But I would experiment with using fused salts such as nitrates, and also experiment with solvents, and acids to remove the coatings. A hot sulfuric acid nitric acid mix will even dissolve carbon, as well as experiment with solvent removal and after treatments to make the fiberglass fibers have better bond properties

There is a pure white Portland cement that you should investigate the availability of, for possible inside finishing

Advanced ideas to try

I have done some thought on the use of combining chemistry and architecture to make much cheaper housing for third world countries. And when you realize that the printed circuit board in your TV set is at least occasionally made of paper urea formaldehyde, and has such reasonably good structural properties and yet all the materials are so much more easily made than are the usual plastic resins. Formaldehyde can be made by heating methyl alcohol, also known as wood alcohol, simply by passing the vapors over a catalyst with some air. Methyl alcohol can be made wherever charcoal is made, not just wood will work for its production. The alcohol actually comes from the lignin component in the wood. Urea can be made from animal urine along with some simple synthetic methods. While paper can be made from almost any natural fiber. Also to be considered might be furfural alcohol as it can be experimented with, of interest because its made from agricultural products and that may make it more practical in third world countries as every thing should me able to be made by they simple means. However to make these products durable for long term outdoors use it may still be necessary to use something like an aluminum foil outer finish

It should also become obvious here, as you will understand more when I show the dimensions needed for domes and how they simply repeat. By also having curved surfaces made of smaller curved surfaces you may gain a quite reasonable amount of extra strength, where otherwise a double wall sandwich foam construction or just a thicker wall would otherwise be needed. But for this to work in helping third world development, you would need to have the original master molds made with all the complexity already taken care of so that they would only need to make more molds and train people to make the materials. Also remember to read on my experiments on plastic recycling just in case it leads to usable ideas

On the building of the new Atlantis

O.K. so I’m a little optimistic, so sue me. This is an idea I would really want to experiment more with and hope someone out there, also shares my enthusiasm for the possibilities of developing a cheap easy way for the do it yourselfer to make safe and usable underwater domes. This became interesting to me when I first learned just how strong reinforced cement can be, when in form resistant structures such as spheres. Also after I had learned about the acrylic, transparent bubble submersibles that are actually of very high performance. Considering they are only about 5 inch thick plastic and about 5 feet diameter and good a few thousand ft down.Remember that cement is strongest in compression and that is just ideal for underwater spheres, if your not looking for the super performance of titanium or some other such thing. Its of interest that even underwater just 30 ft you are almost totally not bothered by storms and waves that would nearly demolish a boat.

However before this is all that likely to happen some problems I see is

How to make these so that as new people make their own, they will be able to join the colony by making sure all the seals fit neatly onto others that serve as a sort of roadway to all the other domes. I have wondered about using old tractor tires as the seal between structures

How to increase the durability of reinforcement or what else to use in place of steel. Some notes here is that calcium nitrite will inhibit corrosion. This has been included in polypropylene fibers and coated with polygol. So when pH changes it will release the calcium nitrite, but its probably not so permanent Also possible help would be to epoxy coat the entire sphere and attaching sacrificial replaceable Zinc anodes by a conductive connection to the reinforcements might help. Its possible that stainless steel, even if obtained as scrap may at least be an improvement, and the cheapest of these is chromium stainless alloys. Some actually stain severely but wont rust and all are magnetic, are often seen in exhaust system pipes for automobiles as well but usually only part of the system is this material. I suspect because otherwise the system would last to long, it makes me mad too but maybe I'm to suspicious. However stainless can have problems with salt water in oxygen scarce places so I don't know what to expect of any stainless in concrete. However I have noticed in my information sources that fiberglass rods may actually be excellent.But here you might find it interesting that wile its specific strength i.e. stiffness based on weight, is about .80 for steel, its 2.1 for regular e fiberglass the ‘low performance common type’ in tensile strength making the fiberglass a little more than 2.5 times stronger than steel for its weight. This can however be like reinforcing with elastic bands if only the strength of how much it can hold without breaking was considered. Actually stiffness however biased on weight is just slightly less for the fiberglass. I have notice that fiberglass strands can be the cheapest form of it. Years ago when the cheapest woven fiberglass was a little more than $2 Canadian a pound I got the strand for something about 1/2 that price . I have no idea what bulk prices would be or if my purchase was any exception. To use fiberglass I have on occasion applied epoxy to the fiberglass and then when tacky applied sand to it to give a surface that cement will bond to, this can work for wood as well but I haven't done any extensive testing . However it may turn out that its not so important that the rods bond as long as they are anchored at the ends in the cement

Lots of other possible problems such as what one would use to weight the structure down so it will stay down and the type of attachments, sewage hock ups. Safety systems, laws etc. .But don't forget the implications of doing all this in international waters beyond the 200 mile limit , you could in theory create your own laws and your own civilization perhaps an international one

WHY THE FLOATING DOME IDEA

As in airplanes if you use a larger motor you need larger wings, landing gear etc. and the whole thing lands up weighing more and not performing any better than the smaller plane, just carrying a larger load. I have come to wonder how much of this also applies to boats as even larger boats seam better designed to carry large loads even when the main cargo is just empty space as can be the case with luxury boats. Then came geodesic domes that are all strength with little weight as is also the case with space frames. (Space frame is a structure made by large numbers of pipes or rods etc. built as a framework to keep an upper and lower layer apart , much the same way tubing gets its strength by spacing material out ). O.K. what if we combine the two made together for maximum strength and put the whole structure on pontoon's maybe 4 , Of course put a railing around it that also helps strength and lots of lightweight furniture because despite the greatest success in making the structure strong , it still doesn't have much floating capacity with just small pontoons to float it . You might consider some stilts that could be lowered and then used to jack the structure out of the water level, to make it stable near land. Small water displacement can be a real advantage when you realize how little horsepower it should take to move a very large structure quickly. I have been hoping to build one of these myself and do so by using old lawn chair tubing to make the space frame but first I need to make the mold to make the fiberglass clamps to attach them together. I have no idea if these structures might need to be far more rugged for Open Ocean use but that also may depend on size and all sorts of other details to be considered but still may be good for the project experimenter. I hope to, sometime in the future, have my own plans, on my own experiences building one myself.

Also it may be worth thinking about using inflatable water bags under the structure that can be used as ballast and inflated. Possibly under the water, with water to stabilize the structure for storm stability, it may work better below water because it doesn't add any weight except if the structure tries to lift the bag out of the water, in its attempt to role over, perhaps use old water beds

                                                           DOMES 2