The column is a design feature in modern designs. In historical buildings it was a structural necessity, serving to hold the roof structure. The architectural science of the period was without the arch and other means of bearing weight in buildings. Some ancient Mediterranean civilizations like the Egyptians and the Persians used columns entirely for the practical purpose of holding the roof inside the buildings. They decorated the outside walls with sculptures, reliefs cut into the walls, and painting. Columns were kept inside the buildings as weight-bearing elements. The Greeks and Romans saw the decorative value of columns and began constructing them for extensive use outside the buildings as well.
The Ancient Tapered Column.
The tapered columns idea is based on the ancient Roman and Greek design. The taper is a decreasing radius of the column from bottom. This design was strictly an architectural trick invented during the period of the ancient civilizations. To have a smaller top than bottom means that the top of the column will look smaller and the building will look taller. In a way, the tapered column is supposed to look like a non-tapered column on a taller building.
The principle of tapered design in architecture is now employed in the design of window frames and other visual building elements.
By the middle ages, new weight-bearing technology like the arch largely superseded the use of columns and the classical forms were largely abandoned. The trouble with columns was that they took a lot of space inside the building and did not allow for large internal spaces like cathedrals.
The straight or non-tapered design is a recent innovation. Because, in most cases, the column in a modern building is a decorative or architectural feature, not a fundamental weight-bearing structure, it could be designed more simply. Structurally meaningful columns are still built, mainly of steel or concrete, but these columns largely combine a decorative as well as a minor structural use. They might be chosen to give a building a "classical" or "post-classical" look.
Straight and Tapered Column Design.
Columns are often used on the exterior of a home to hold a roof structure around an entranceway. Most columns are used for decorative purposes in modern building. They often appear as freestanding sculptures. Many people use column elements to suggest Greek or Roman "classical" decor. They are often built into large bathrooms, entry halls, or beside a fireplace. There are occasions when a column is actually bearing some weight in holding up part of a ceiling.
Many "tapered columns" in modern decorative use are framed square columns, not round," made of wood. Square "Tapered" columns for porches and other decorative uses are often made by converting porch posts using PVC or wooden wraps.
Round tapered columns can still be purchased in lengths up to 30 feet. These are typically made of composite fiberglass, synthetic stone, or PVC materials and are molded. They usually have to be custom ordered. A specific shop drawing may have to be provided, based on the material along with any weight-bearing specifications.
Making the column straight and non-tapered means that it can be cut to any length to be used for a structure of any height. The cap and base of the column will fit no matter how long the column is. Manufacture is less expensive and the columns can be ordered off the shelf. Most round columns are made of fiberglass, PVC, sometimes of wood. They can be sold in a variety of diameters, commonly up to 36 inches. These materials are easy to shape and relatively lightweight. Round columns can come in a variety of styles, plain and fluted, with various bases like Tuscan or Attic base options.