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Terminating Versus Supporting Moldings

If I were to say: “Hi are how you? Brent I’m Hull.” You might wonder what I drank for breakfast. I mean, you’d recognize the words, they’d sound familiar, but the way I used them wouldn’t make any sense. But if I said: “Hi, how are you? I’m Brent Hull,” you’d respond without a hitch, my words would make perfect sense (depending on what you drank for breakfast!).

Well guess what? There is a language to classical design, too; a vocabulary that’s dependent on moldings for communicating purpose in a room. If you speak the language, all your finish work—your, bookcases, mantelpieces, doorways, and ceilings―will communicate fluently with your customers.

(Note: Click any image to see a larger version. Hit "back" button to return to article.)

If you don’t speak the language, your work will look funny and awkward. Put simply: You might be using the right words, but if you put them in the wrong order or upside down, they won’t make sense.

Supporting Moldings

Centuries ago, the Greeks and Romans worked out a set of rules for moldings. Each profile had its place and purpose. Some shapes were designed merely to embellish an architectural detail, while others served to separate architectural details. The two profiles that are most often confused and most often used incorrectly by today’s builders are terminating profiles that finish an architectural detail, and supporting profiles that hold or carry a weight above.

In the forward to Theory of Mouldings (C. Howlard Walker, reprinted 2007), Richard Sammons provides a great definition and an easy way of determining whether a molding is terminating or supporting. Sammons says that if the final line of the molding curve is pointing out, it is a terminating molding; if the final line of the curve is pointing up, it is a supporting molding. Or put another way, terminating moldings have a concave curve at the top, and supporting moldings have a convex curve at the top.

Let’s take a look at supporting moldings first. Supporting moldings have more meat or muscle on the bone near the top. They don’t look delicate! They look like a clinched fist on the end of your forearm. A perfect example of a supporting molding is a corbel, the embodiment of strength in architecture.

Some supporting moldings play a more subtle role. While the corbel forms the main support for the mantelpiece, look closely and notice the molding beneath the mantelpiece. You may be quick to label this profile as crown molding, but it’s actually bed molding. The top of the bed molding profile points up not out, so it adds another layer of visual support to the mantle above.

Band molding or panel moldings, in all their various shapes and sizes (from egg-and-dart molding to lamb’s tongue, to ogee chair rail and dado moldings), are another example of supporting moldings. The top curves on band and panel moldings are convex, putting muscle where it’s needed most – at the top of the profile.

Terminating Moldings

Terminating moldings are exactly the opposite, they’re much more delicate on the upper top edge, a clear sign that they’re not meant to support any weight from above. Though they might seem purely decorative, terminating moldings actually served an important purpose on classical structures. Like the brim of a hat, they helped deflect rain away from the wall below. Today, the most common pre-formed rain gutter actually uses a modified shape of crown molding, the most common of the terminating moldings.

The top of crown molding curves out, finishing the top of – or “crowning” – any architectural detail it’s attached to, from the mantle piece to the rake of the beautiful open pediment. Most crown moldings used today are called cyma moldings because they combine both concave and convex curves to form their profiles. Cyma recta is the classic crown shape with the top concave curve pointing out. On the other hand Cyma reversa, with the convex curve on top pointing up is the proper profile to use as a supporting molding, beneath a mantelpiece or a shelf.

One area that gets really confusing is crown molding at the corner of the wall and ceiling. Should crown molding at the ceiling be a supporting molding or a terminating molding? Actually, the wall in a home is meant to resemble a classical column – so the uppermost crown should be a terminating molding. But sometimes it’s not. I’ve frequently installed a supporting molding at the ceiling when I’ve used a one-piece crown, but most often when there’s a secondary soffit or light well above, which must
also be trimmed with crown.

Terminating moldings help produce dramatic effect at the top or termination of everything we build. As Marianne Cusato and Ben Pentreath put it in their book Get Your House Right, (also co-written by Richard Sammons): “The emphasis of a terminating molding, or cyma is outward.” That outward projection works as a lip or an outline to finish off any architectural detail.

Cyma Recta

No discussion of supporting and terminating moldings would be complete without a look at the two primal shapes that form the foundation for most moldings.

Cyma Reversa

These two opposing profiles follow the same classical rule: if the upper line of the molding points out, it’s a terminating profile. If the upper line of the molding points up, it’s a supporting profile. Supporting profiles always have more mass at the top. Terminating profiles always have less material at the top.

Cove molding is another profile that can be used as terminating molding. The delicate lip at the top of a cove’s concave curve works well to finish off less ornate architectural details. Many terminating crown patterns incorporate a deep cove to emphasize the projection of the terminating molding.

Finishing Up

Too often supporting and terminating moldings are installed backwards, upside down, or they are swapped in position and make no architectural sense. Too often a terminating molding is placed underneath something it can’t carry visually. For example, the ubiquitous 8010 crown should be used to finish off a detail, and too often we see it installed underneath something heavy, leaving us to wonder what it is about that detail that we don’t like or that doesn’t feel quite right.

The area in architecture where I see these moldings most often mis-used is mantles and shelves. It is very common to see a terminating molding get capped by a large block or thick piece of wood, which happens frequently with mantel shelves.

Wrong

I see this type of composition all the time! Now that you know better, it’s easy to see that the thin top of that crown molding isn’t strong enough to carry the weight of that heavy shelf. A supporting molding would have made much more sense.

Right

This is how a classical cornice should be constructed, with a cyma reversa supporting molding beneath the soffit and a cyma recta terminating at the top!

Never ask a terminating molding to visually carry something so large and heavy. And by the same token don’t finish off the top of a detail like a door header or mantle with a supporting molding that visually begs to carry something heavy above it.

Remember, a simple twist or rearrangement of words, and suddenly your sentences make sense—or they don’t! The proper use of terminating and supporting moldings can make your bookcases, mantels, cornices, and crown feel right and make visual sense. Understanding and applying these ancient rules will improve the value of your craftsmanship, and increase the value of your work in the eyes of your clients, too.

Read this article in its original format (with more images) at TiC Issue 1!

Comments/Discussion

4 Responses to “Terminating Versus Supporting Moldings”

  1. calvin

    I remember reading Gary on this subject which led me to come to understand it. However, I need to think of a good way to remember the terms when applying it in conversation. In 38 yrs I’ve probably worked on 10 mantles.

    I’ll have to see if you talk about the rules and shapes of column bases in the first issue.

    thanks.

    Reply
  2. Bill

    Hi Brent,

    What a great explanation of how these mouldings should be used. I have to admit that I am not fluent in the language of mouldings. But I expect my future work will be more satisfying now.

    I really like the open pediment shown in your article and was wondering if you have an un-cropped version or a link that we could see the entire structure?

    Thanks again
    Bill

    Reply
  3. Ken

    Brent,
    The last photo shows what looks to me to be a terminating profile that curves out just underneath the marked cyma reversa. One thing I’m sure of is where in the vertical stack (other than at the top) is it right or wrong to put one or the other?
    Personally, I like the look of the two combined as they are. It seems that the profiles complement one another.

    Thanks for the information,

    Ken

    Reply
  4. Kyle

    Great read! I’ve been inspired to learn more about molding design. As a apprentice I just build what’s been drawn on the wall or paper. I’ve been paying attention to what we use for moldings and where but WHY is what I really want to know. Then I will be able to design my own projects with the consistency people expect. Thanks!

    Reply

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