Dentil molding on a gable: plumb or square?
What’s the correct way to run dentil molding on a gable end: plumb to the world or square to the rake?
Aaron Parret, Great Falls, MT
Brent Hull, owner of Hull Historical Millwork in Fort Worth, Texas, replies: Dentil molding often is used arbitrarily and, consequently, incorrectly on many buildings. A quick history lesson offers clues on how to use dentils. Like most classical moldings, the dentil is thought to represent a supporting beam holding up the roof. Nowadays, these beams are typically 2x joists and rafters, but the structural load paths are the same. For a structural member, the most strength is achieved when the element is plumb to the viewer.
The other thing history tells us is that dentils normally appear only on the Ionic, Corinthian, and Composite orders. Because these orders are higher (read: more decorative) than Tuscan and Doric, we know that the dentil is not appropriate on simple buildings. Be careful when using the dentil. Details matter. The proper use on the right building can make a big difference and will tell a lot about your ability to design as well as build. For more information about designing according to classical orders, see “Drawing Board,” FHB #161, pgs. 134 and 136.