This is a drawing I did awhile back of the Classical Orders of Architecture. What is unique about this drawing is that the columns are depicted at the same height throughout, but with varying shaft diameters, starting with the Tuscan being the fattest and the Corinthian and Composite being the most slender. Usually, the orders are drawn with similar base diameters, but with varying heights, starting with the Tuscan being the shortest and the Corinthian and Composite being the tallest. When I started studying the Classical Orders, I soon realized that the ratio of column height to entablature height was 1 to 4, or another way to look at it, if the portion of the facade with the columns (or pilasters) and entablature is divided into 5 equal height bands, the entablature would occupy the upper band and the lower four bands would be reserved for the columns or pilasters. This works out regardless of the order.
Tuscan: Column Height = 7 diameters; Entablature Height = 1.75 diameters.
Doric: Column Height = 8 diameters; Entablature Height = 2 diameters.
Ionic: Column Height = 9 diameters; Entablature Height = 2.25 diameters.
Corinthian and Composite: Column Height =10 diameters; Entablature Height = 2.5 diameters.
Another advantage to depicting all the orders at the same height is that often the overall height that is required is known, and the column diameter has to be solved by dividing the overall height into the proper number of modular units. For example, if your are working within a room, you usually know what the floor to ceiling height is, and if the Corinthian Order is desired, then the height is divided by 12.5 (10 + 2.5) to establish the required column diameter. It seems rare that it would occur the other way around, where a column diameter is selected and the height must be determined. This also makes it easier to swap out one order for another during schematic design, if the Ionic Order is preferred over Corinthian, then divide the ceiling height by 11.25 (9 + 2.25) to achieve the required column diameter.
Optional components of the Classical Orders include the pedestal and the balustrade/parapet. The columns may stand directly on the building’s base or water table (or on a lower order) without the pedestal. Similarly, the facade may have a pitched roof that sits directly on top of the cornice without the need for a balustrade or parapet.
To achieve the heights of these components I used the same 1 to 4 ratio as with the column and entablature. The balustrade/parapet is 4/5 the height of the entablature, or the column height can be divided into five to determine the balustrade or parapet height. The pedestal height is shown as being 1/4 the height of the column + the entablature. (I’ve taken some liberties here; more often the pedestal is depicted as being 1/3 the column height, but I felt compelled to continue the 1 to 4 ratio as a theme throughout.) According to Robert Chitham‘s book on the Classical Orders, he indicates that James Gibbs used this method for determining the pedestal height, so it can’t be all wrong.
Finally, I’ve used the same 1 to 4 proportion to determine the pedestal base height from the pedestal’s overall height and the balustrade/parapet’s base height form it’s overall height. The pedestal cap and the balustrade cap is determined by the taking remaining height of the pedestal or balustrade/parapet and again divided into 5.
The next thing to notice on this drawing is that certain alignments must occur for the Classical Orders to look right. When these alignments are ignored, for example, if the base is too wide, or the soffit of the entablature is too wide, it makes the column appear to be weak or over burdened in its effort to support the loads.
The alignments, starting at the bottom, are that the pedestal width aligns with the width of the column plinth; the width of the entablature’s soffit aligns with the upper shaft of the columns. (The columns have entasis, which is a gradual tapering of the upper two thirds of the column shaft, the lower third remaining cylindrical.) The planar face of the balustrade or parapet base aligns with the base plane of the entablature (the frieze if it is without relief and the bottom of the architrave). There is a continual diminishing of material as the facade increases in height. This makes since because the base of the facade must be thicker to carry more weight, and the upper portions must be lighter to not over burden the supports below.
As for the column’s entasis, I’ve shown the top diameter of the equal to 7/8 that of the base. This is not exactly right, but it is close. The purpose for using 7/8 was to make it easier for carpenters (again some liberties taken).
Modern lightweight frame construction has made it easy for architects to ignore this alignment of components and the required diminishing of material, and it is this perhaps more than anything, makes an amateur’s work stand out among one who thoroughly studies classical architecture.
Finally, there are some specific dimensions related to each of the orders. The Tuscan entablature includes an architrave that is .5 diameters in height, a frieze that is .5 diameters in height, and a cornice that is .75 diameters in height (.5 + .5 + .75 = 1.75, which is 1/4 of 7, the column height). The Doric has an architrave that is .5 diameters in height, a frieze that is .75 diameters in height, and a cornice that is .75 diameters in height (.5 + .75 + .75 = 2, which is 1/4 of 8). Also the Doric’s frieze has an alternating pattern of metopes and triglyphs. The metopes are square, or .75 diameters wide and the triglyphs are .5 diameters wide, with a vertical proportion of 2 to 3. The intercolumniation of the Doric, or the spacing of the columns, is done in increments of 1.25 diameters (1.25, 2.5, 3.75, 4.5) so that the column is always centered on the triglyphs.
The Ionic has an architrave, frieze and cornice heights of 5/8, 6/8 and 7/8 respectively. (5/8 + 6/8 + 7/8 = 2.25, which is 1/4 of 9). The Ionic cornice has a continuous band of dentils, therefore the intercolumniation is not as critical as the Doric. The Corinthian and Composite both have architraves that are .75 diameters in height, friezes that are .75 diameters in height, and cornices that are 1 diameter in height (.75 + .75 + 1 = 2.5, which is 1/4 of 10). The Corinthian and Composite cornice both have modillions that are spaced at increments of 2/3 diameters, starting with 1 1/3 and moving upwards (1 1/3, 2, 2 2/3, 3 1/3, 4).
Notice also that when modillions are used at a corner, the column center lines are aligned with the second modillion from the corner, and the outside face of the modillions at the corners align with back fascia of the adjacent side.
There is so much more to classical architecture, including proportion, composition, hierarchy, etc. that can’t be covered in this blog post, but it is hoped that builders, carpenters and designers who are unfamiliar with the Classical Orders will find this to be a helpful worksheet and introduction to their proper use.