Domes have been popular in the construction of buildings since ancient times. They have the advantageous characteristic of withstanding adverse climatic conditions such as earthquakes, tornadoes, floods, hurricanes and tropical storms. Earlier domes were used only in religious buildings, but more recently they have been found in residential buildings as well. Houses with domes are usually found in regions that experience heavy winds and extreme climatic conditions. The trend can also be seen in public structures such as schools and colleges.
The dome is a structurally sound design. These days they often made of concrete and reinforced by steel. The main advantage of this style of design is that it is heavier in weight, making it difficult to lift it off its base. Moreover, besides the weight of steel and concrete, the shape of the dome itself makes it a very solid structure. According to architects, the arches of the dome are naturally strong and are hardly influenced by extreme external forces like tornadoes. Also with no flat walls, these kinds of structures have very few seams, leading to less penetration of water in the construction especially during tropical storms. Moreover, using archways as gates on either side of the building can also help water to run straight off without causing any lasting damage.
Techniques for Constructing Domes
One method for contructing domes is the flattened conduit method. This involves the molding and flattening of metal tubes. After slightly bending the tubes, a hole is drilled on both the ends of the structure using frames and various other tools. This method is simple and less time-consuming, but the structure that is formed must be with other materials as the joints don’t have fine finishing.
Another method for is the tube and hub style. This is a very simple, cheap, and professional method which requires the joining of the struts with a larger diameter pipe at the hub holes. However, the method involves no option for rectifying a damaged hard cover material.
Though a dome structure lasts for a long time, it doesn’t need any specialist tools. It does have it’s drawbacks however. Poor ventilation in a dome can lead to problems such as damp and dry rot. To avoid this wooden beams are used while joining the metal hubs at the edges with outside plywood. This method of building is called the panelized timber frame. This is a simple strategy which only requires panels to be nailed together in the correct order. However, as the panels used in the process are not custom-made, the options available for the design are few. It should be noted that wooden beams cannot be used for constructing domes for regions with extreme climate conditions.
Modern Techniques for Constructing Domes
The stressed skin technique is one more modern building method. This uses metal or fiberglass panels riveted together. The method saves costs and doesn’t require any beams or support structure. However, to prevent any kind of condensation, it becomes necessary to install insulators in the structure.
The monolithic, yet modern type of dome construction is made of three phases. This involves using a special type of membrane that is inflated and placed on the dome, giving it a finish that serves like a weather-proof skin, but that can also be damaged very easily. Unlike the previous method, this style involves the spraying of polyurethane foam to insulate the structure. However, the materials used in the process are not environmentally friendly as they have oil-based chemicals.
The space frame type of dome construction, generally observed at airports and exhibition halls, heavily relies on connecting struts to spherical structures that have slots machined into them.
One of the oldest techniques of earth architecture is the brick strategy, which was often used to construct bridges and arches. In this technique, concrete, brick or stone are put on top of a wooden frame, which is molded according to the desired shape. The mold helps in holding the stone or brick in place until it settles and supports the whole structure.
One more recent technique is the foam and render method using polystyrene foam. The dome shape is made by cutting and sticking the foam together. Chicken wire serves the purpose of reinforcing mesh. Lastly, in order to ensure that the structure is weatherproof, a thin layer of cement is spread over the entire building. These conditions only favor construction of small domes.
Of all the methods, the geodesic type of dome has been the most famous and extensively used in the last century. The main advantage of this dome structure is that it provides a massive enclosed space without any type of hindrance or support system. Moreover, geodesic dome construction can be erected easily and quickly using lightweight materials and a very small crew. There have also been several advancements made in geodesic dome construction methods in the past few years. Nowadays, several companies sell plans and dome materials along with instruction so that the owners can make the dome themselves.
Dome structures, though advantageous, don’t match urban planning styles and do not mix well with walls and angled rooftops. However, unlike other construction designs, domes are strong and resistant enough to bear bad weather conditions such as electrical storms, lightning, and earthquakes.
- Photo of Reichstag by Rebecca Kennison.Lear 21 at en.wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], from Wikimedia Commons
- Photo of Padova - Basilica di S. Antonio by MarkusMark (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
- Pantheon Drawing in the Public Domain via Wikimedia Commons