Installing of Molding
WORKING WITH MOLDINGS
When trimming out a room, start with what finish carpenters call the “standing trim”-the door and window casings. The first step is to check to see if the edge of the jamb is flush with the wall surface; if it projects beyond the surface, you’ll have to plane it flush. If the jamb is recessed, nail and glue a thin strip of material over the edge to bring it flush with the wall.
To trim a window, first cut the stool to length. The casings are set back from the face of the jamb about 1/16″ on either side; this “reveal” is almost unnoticeable, but it allows you to adjust the casing slightly if the window is not quite plumb.
The first step is installing the stool. Measure the distance between the side jambs, then add 1/8″ for both sides of the reveal, then add twice the width of the casing, then add 2- 1/2″ so the stool will project 1-1/4″ on each side. For example, if the jamb-to-jamb measurement of the window is 36″ and you’re using 2-1/4″ casing, you’d cut the stool to 43-1/8″ (36″ + 1/8″ + 2-1/4″ + 2-1/4″ + 2-1/2″ = 43-1/8″).
Measure up each side of the window from the stool to the head jamb (on a door, measure from the floor to the head jamb). If the dimensions are not equal, use the longer dimension. Add 1/16″ and miter-cut the side casings with the short side of the miter matching your measurement. Position the side casings with a 1/16″ reveal all along the length of the side jamb (Fig. 5) and nail them in place with 6d finish nails 24″ on center. Use two nails at each location; drive one into the jamb and the other through the wall surface and into the stud.
Position a piece of casing over the head of the window, slightly longer than the outside edges of the side casings. Use the miter cut on the side to mark your cut on the head casing. Cut the head casing to length. Apply wood glue to the miters and set the head casing in place. Nail it to the jamb and wall as you did the side casings, then drive a 4d finish nail through the side casing into the end of the head casing on each side.
Once the door and windows are finished, you’re ready to install the “running trim”-the ceiling and base moldings.