February 4, 2011 Greg Shue, AIA

This article by Greg Shue first appeared in the Fall 2006 issue of Design Lines magazine, a periodical published by the American Institute of Building Designers.

Post-and-beam (trabeated) construction is arguably the most influential building system ever invented. Considering that the wood stud wall is based on post-and-beam principles, and the sheer number of wood framed buildings around the globe, it’s no wonder that most traditional building styles involve a trabeated arrangement of elements. The trabeated system is the fundamental principle of Neolithic architecture, Ancient Egyptian architecture, and Ancient Greek architecture. Other trabeated styles are the Persian, Lycian, nearly all the Indian styles, the Chinese, Japanese and South American styles.

The history of post-and-beam building started long before the time of Stonehenge, the most famous Neolithic monument from about 2,750 BC. Here, monolithic stones were used as both posts and beams in a configuration that celebrates the earth’s relationship with the rest of the cosmos. So stable is the arrangement of the stones, that many still exist today (Figure 1).

Figure 1

Figure 1: Stonehenge in Wiltshire, England, from around 2,750 BC

Over the next few millennia, building technologies developed into what we now study as ancient Egyptian architecture. Clearly the scale increased, as did the spans between vertical supports and the amount of ornamentation with painting and sculpture (Figure 2). Fine artisanship documents the pride and cultural advancement the Ancient Egyptians achieved.

Figure 2

Figure 2: Post-and beam construction from Ancient Egypt, from about 1,152 BC

Thousands of years later, the Ancient Egyptian building traditions migrated northward and were refined further in Classical Greece and Rome as exemplified by the classical orders, which became the basis for the traditions we currently know today as the Western building tradition. All kinds of buildings, including homes, are identifiably traditional through the use of the classical language of building (Figures 3 and 4).

Figure 3

Figure 3: Monticello, home of Thomas Jefferson, built in 1768

Figure 4

Figure 4: New traditional architecture in Prospect New Town in Longmont, CO, 2005

Like many ideas that were developed by the Ancients, Plato and Pythagoras in particular, architectural elements were commonly divided into three parts, expressing a beginning, middle, and end; or similarly a bottom, middle, and top. If we take the classical orders as an example, we can see that they can be divided into pedestal, column, and entablature (or beam). The pedestal can be further divided into three parts: plinth, dado, and cornice; the column into three parts: base, shaft, and capital; and the entablature into three parts: architrave, frieze, and cornice (Figure 5).

Figure 5

Figure 5: Tri-partition of the classical orders (1)

The ancient Greeks and Romans refined the classical orders into five basic categories. Each order can be described in terms of the diameter of the lowest third of the shaft (D). In their order of sophistication, the orders are:

Tuscan: Col. ht.=7D, Entab. ht.=1.75D
Doric: Col. ht.=8D, Entab. ht.=2D
Ionic: Col. ht.=9D, Entab. ht.=2.25D
Corinthian: Col. ht.=10D, Entab. ht.=2.5D
Composite: Col. ht.=10D, Entab. ht.=2.5D

[nota bene: Entablatures are 1/4 the height of the column as a rule of thumb]

Pedestal heights are commonly one third the height of the column.

The successful execution of classical elements can be largely dependent on the accuracy of subtle details. One of these details is the taper of the top two thirds of the column shaft (Figure 6). This taper is called entasis, and was originally created to visually correct the distortion caused by the height of the column and its interpretation by the human eye. Where beams intersect walls, an engaged pier, or pilaster, is usually placed to visually support the entablature at that connection. Pilasters typically have the same base diameters as adjacent columns, and entasis is optional.

Figure 6

Figure 6: Various methods to determine entasis (3)

Round columns that touch the wall are called engaged columns. They commonly protrude from the wall 5/8D or 3/4D and almost always have entasis. Another common relationship between column and beam involves the architrave (or bottom of the entablature) having the same width as the top of the column shaft below (Figure 7). In the case of pilasters without entasis, the width at the top of the pilaster shaft slightly exceeds the width of the architrave. Also, the spans of the entablature (or beam) usually do not exceed the height of the column, as a rule of thumb.

Figure 7

Figure 7: The architrave commonly aligns with the top of the column shaft below (2)

Some designs call for a formal treatment of interior spaces, where the walls are commonly treated with literal, implied, or an otherwise referential application of the orders (Figure 8). For example, the pedestal can become the wall base, dado and chair rail; the column height can determine the wall height above the chair rail, and the entablature can determine the crown height of the room. Often, the frieze of the entablature is omitted in such interior applications.

Figure 8

Figure 8: The application of the classical orders to interior spaces (1)

Many books provide more in-depth information, a partial list includes:

  • Introductory and foundational information:
    • The American Vignola: A Guide to the Making of Classical Architecture- Ware
    • Classical Architecture- Adam, and Brentnall (Illustrator)
    • The Classical Language of Architecture- Summerson
  • Information on further refinement:
    • The Classical Orders of Architecture- Chitham
    • The Architecture of the Classical Interior- Semes
    • Learning from Palladio- Mitrovic
  • More advanced reading:
    • The Elements of Classical Architecture- Gromort and Reed
    • The Ten Books on Architecture- Vitruvius
    • Classical Architecture: The Poetics of Order- Tzonis

Organizations also exist as resources for further study, a list of which includes:
The Institute of Classical Architecture & Classical America (

With regional chapters in:
Charleston, SC (
Charlotte, NC (
Washington D.C. (
Boston, MA (
San Francisco, CA (
Philadelphia PA (
Atlanta, GA (
Los Angeles, CA (
Nashville, TN (

[nota bene: there are now more chapters – see]

International Network for Traditional Building, Architecture, & Urbanism (
The University of Notre Dame (
The University of Miami (
Andrews University (
Prince’s Foundation (

1 Image source: Classical Architecture by Adam and Brentnall (Illustrator), published by Harry N Abrams (April 25, 1991)

2 Image source: The American Vignola: A Guide to the Making of Classical Architecture by William R. Ware, published by W W Norton & Co Inc (June 1977)

3 Image source: The Elements of Classical Architecture by Georges Gromort, published by WW Norton (2001)

The information that has been provided in this article is intended to be introductory and an impetus for further study. There are endless variations on the rules-of-thumb that have been outlined above, all of which contribute to the fantastic diversity of our built environment.