Butted Door Casing

In this classic casing style, side and head casing meet with a simple butt joint, and the head casing overhangs the side casing by about 1 inch at each end. The inside edges of the casing are off-set from those of the jambs, leaving a 1-inch reveal. Decorative rosettes can be added at the top corners if desired.

Rather than resting on the floor, the side casing usually rests on a pair of plinth blocks slightly thicker and wider than the casing and 1 inch taller than the baseboard.

Preparing the Jamb: Since the casing links the jamb and the wall, these two surfaces must be flush. If the jamb is slightly proud of the wall, plane it down. Where it is slightly shy of the wall, shave down the wallboard with a rasp; but if the jamb is set back more than 1 inch from the wall, make and install a jamb extension of the same type used for a stool-and-apron window.

Attaching the Casing

1. Marking the Reveal.

Remove the door.

Set a combination square to ¼ inch, checking that this is wide enough to clear the hinges. Butting the handle of the square against the face of a side jamb and resting a pencil against the end of the ruler, mark a reveal line the length of the jamb edge (above).

Mark the same reveal on the other side jamb as well as on the head jamb.

2. Finishing the Job.

Install the next panel so its lapped edge meshes with the first. Avoiding the joint, nail the edge of the second panel to the stud (left); this will leave the first panel free to expand.

Install the rest of the siding this way. Trim the corner panels and Z-flashing as needed using tin snips to cut the flashing.

Cover the exposed edges of the siding at the corners with 1-by-3s and 1-by-4s fastened with 2 1/4-inch galvanized finishing nails (inset).

2. Fastening the Plinths.

Cut two plinth blocks to the desired height and width. If desired, bevel one edge of the blocks with a power or manual miter saw; to cut larger stock with a power saw, you may need a compound miter saw.

Align the edge of a block with the reveal line—if the finish flooring is not yet in place, set a scrap of wood the thickness of the flooring under the plinth block.

Nail the plinth block to the jamb and to the rough framing.

3. Attaching the Head Casing.

Measure the distance between the reveal lines on the two side jambs. Add to this figure the width of both of the side casings to be used plus 1 1/2 inches and cut the head casing to this length.

Mark the center of the head jamb and the head casing. Align the head casing with the reveal mark and line up the two center marks.

Nail the casing to the jamb and the rough framing.

4. Fitting in the Side Casing.

Cut the side casings to fit snugly between the plinths and head casing.

Fit one piece into position, aligning it with the reveal line (left). Fasten it in the same way as the head casing, then put up the other side piece.

With a nail set, sink all the nails. If you plan to paint the casing, fill the holes with spackling compound; otherwise use wood putty.