Dressing Up Window Trim
Back bandings and built-up moldings add a level of detail and visual impact to traditional window casings.
Some traditional window trims feature back bandings or built-up moldings that run around the outside perimeter of the casings, adding a great deal of visual impact. They also add thickness to the edge of the casing, allowing wainscot or chair rail to butt into the window trim without overlapping it. These additional layers may be site-built with a simple profile or be made up of more complex purchased moldings. You install back bandings and built-up moldings after the casings are in place.
When applying a molding to the face of the casing you must be careful to keep the sides even with one another as any unevenness easily draws attention. Using a back banding in combination with an applied face molding that covers the edge joint eliminates the problem. Alternatively, a rabbeted side band also serves to hide the edge joint. Not surprising, these perimeter moldings add a good deal of time to the overall installation—though the overall effect can be well worth the effort and offer a good solution to trim intersection problems.
The trim variations shown here represent a wide variety of styles, although really elaborate perimeter moldings are usually associated with colonial styles. As you can see, back banding can be applied to casing that is joined with miters or butt joints. Most of these examples were made using off-the-shelf moldings. A few were made with custom profiles cut on a router table.
Install back banding in a sequence similar to flat casings. Fit and nail both sides and then fit and nail the head piece. On multilayered casings, you may need to even up the outside edges with a hand plane.
Common Ways to Add Detail to Window Trim
Mitered Casing with Back Band
Simple Butted Casing
Layers of Thicker Stock
Intermediate Molding and Bead
Bed Molding and Bead
Drawings by Trevor Johnston.
Excerpted from Trim Complete: Expert advice from start to finish by Greg Kossow.