How To Select the Right Interior Trim Proportions for Your Home
Interior trim proportions are important; they give a room its sense of scale. We hear questions like the below often:
How do I select the right size trim for my home? I’ve found crown molding, chair rail and base that I like. But are they the right proportion for the room? Every room is a different shape. Ceiling heights are different. How do I assure continuity from room to room. Floor to floor?
These are very important questions to ask yourself. Especially if you want your home to look beautiful! In this and following posts, I will show you how to make the right decisions.
a little bit of History
First of all, I think a little historical perspective would be helpful.
Have you ever visited a friend’s home or a historic property built in the 18th, 19th or early 20th century and marveled at how right the rooms felt? It’s due to their interior trim proportions. Then, have you wondered how they did it? The answer lies in the principals of the Classical Orders of Architecture, originated by the Greeks and Romans. Using mathematics based on human scale, they developed a system of proportion and scale. In the 1700’s and 1800’s, several well known builders and architects wrote what were called “pattern books” based on these principles.
In the United States, Asher Benjamin wrote several pattern books. Through the 1940’s these books were referred to and used constantly as guides and sources of inspiration by architects and builders as they designed and built homes. Consequently, homes built before this period tend to have pleasing interior trim proportions.
After World War 2, for a variety of reasons, builders and architects turned away from these books. Today they are largely forgotten and ignored. Because of this, most new homes are designed and built as a kit of parts, as opposed to an integrated set of guiding principals in which the parts are seen as being interconnected, with proportions based on human scale, the height and size of a room, etc.
The Magic Numbers
So if there is a system, a set of guiding principals for interior trim proportions, where do you go to find it? How complicated is the system? Is it difficult to learn?
Yes, there is a system. It’s called The Orders of Architecture or The Classical Orders. Yes, it’s very confusing, if you were to try to use the original sources as a guide, such as Vitruvius or Palladio. For instance, below is an illustration of 7 different interpretations of the Doric Order. Even I had difficulty sorting thru the information and formulas!
For simplicity’s sake, I referred to Asher Benjamin’s, “The American Builder’s Companion” to assemble a simple, coherent set of images and guidelines for rooms with 10’, 9’ and 8’ ceiling heights that will help you determine the right proportion and size crown, chair rail and wood base for your home. The true beauty of the Classical Orders is that the interior trim proportions are completely scalable, to whatever room size or ceiling height you are working with, or to the room’s level of finish.
For this post and the Moulding Crib Crib Sheets below, I developed proportions and trim sizes based on the Doric and Ionic Orders. Each order’s proportion is derived from a set of calculations based the height of a column in a room, which in turn defines the diameter of the column, the size of the entablature, cornice, crown, chair rail and base. (NOTE: For the sake of simplicity, I have removed some of the ornamentation from the entablature in both orders.) When you look at the dimensions, particularly the entablature and cornice dimensions, you will notice the Doric Order is bigger. Thus, if you are designing a masculine space, you would want to consider using the Doric Moulding Crib Sheet. Conversely, for a more delicate feel, your should consider using the Ionic Moulding Crib Sheet.
putting together the pieces
So, what do the various profiles look like and how can they be combined in different ways that still make sense? The three diagrams below illustrate how different levels of trim relate one to the other, starting with a full entablature at the ceiling. A personal quirk, I did not draw the entablature with base only because visually it feels top heavy to me. For the same reason I wouldn’t design a full entablature in a room with an 8‘ high ceiling.
The portion of the entablature closest to the ceiling is called the cornice. If you want a certain amount of ornamentation at the ceiling, without the “heaviness” of the entablature, this is the way to go. Notice how you can scale the level finish up and down, from full height paneling to a the cornice with a base.
The most casual interpretation of these Orders is the use of a simple crown at the ceiling. Pair this with various wall trim elements and you can easily create casually elegant architecture as backdrop for your decor and furniture.
Did you notice how the tall narrow panels relates to the size of the column in the images above?
Finally, for yucks and grins, I worked out the proportions of three different historical interpretations of a Doric Column. Look closely at each column. Study their trim and width. Look closely at the height and width of each pedestal. Each one is ever so slightly different. None are wrong.
So for having so carefully prepared those crib sheets for you, my parting message to you is, “Get as close as you can, and don’t loose any sleep over the minutia. It’s going to look great!”
In my next post, I’ll explore mixing and matching entablature, cornice and crown.
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