3/16 is the usual reveal. It's an architectural/aesthetic choice. Depending on the look you could have no reveal (modern looking house). The problem you have is your casing is now too short, so you are stuck.
The reveal is the small gap between the edge of the door jamb (i.e., the frame from which the door is hinged and where the latch engages) and the trim. To outline it, use a combination square to mark a consistent reveal of 1/8 to 1/4 inch around the entire door frame.
Semi-gloss finish: This is the best finish for your trims such as baseboards, mouldings and even cabinets and doors. It's also a good choice for highly trafficked area that gets lots of wear and tear such as a mudroom.
Its also to clear the hinges on that side of the door. Normally I set the reveal based on the how much reveal is needed for the hinge to work properly.
Mark the Reveal Lines
Installing the trim slightly away from the jamb edges will help hide discrepancies. This intentional gap is called a reveal. Use a tape measure and a sharp pencil to mark the jamb 1/8 to 1/4 inches from the inside edge on all sides of the window.
Typically, an installed window should have an 8–10 mm gap between the back of the reveal and the framing trimming the opening. This tolerance allows the window to be fitted into the opening and trued as well as giving sufficient space for the air seal. >
While there is no unwritten rule that all exterior trim should match, matching can make a lot of design sense and make the design appear well thought-out.
The standard reveal for window molding and door trim is 1/4-in., but this can be adjusted a little if needed. A combination square works well for marking reveals. The first step in any trim job is to prepare the jambs for trim. If you're replacing trim, pry it off and remove the nails from the jamb.
A jamb (from French jambe 'leg'), in architecture, is the side-post or lining of a doorway or other aperture. The jambs of a window outside the frame are called reveals.
The right amount of space is equal to the thickness of your door with a little extra room for clearance while opening or closing. For example, if you have a thicker door you would want more space between your door and frame to allow for movement when opening and closing.
The most common and best sheen for interior trim is a satin or semi-gloss finish. Satin paint finishes have a medium sheen and are durable and easy to clean. Semi-gloss paint finishes have a higher sheen and stand out in a room. They are easy to clean and stand up to dirt, stains, mold, and mildew.
Avoid using eggshell paint in high-contact, high-traffic areas such as door and window trim, baseboards, cabinetry, and doors. It's best to use semi-gloss paint in these areas.
A reveal may typically be seen at the edge of a door or window, where the face molding is set back, often by a distance from 3/16" (5 mm) to 1/2" (12 mm). (This noun is unrelated to the verb reveal but is from the obsolete verb revale 'to lower, bring down,' which is related to vale and valley.)
The 50 Percent Rule
Generally, vertical trim elements such as door and window casings should be smaller and have less heft than baseboards. So I've found that a good rule of thumb for sizing window and door casings (or door trim sizes) is to keep them at about 50 percent of the height of the baseboard.
The reveal should be wide enough to accommodate the thickness of the door and provide a secure fit, but not so wide that it becomes visually distracting or takes up too much space in the doorway. The shape can also vary. Some reveals are rectangular, while others are more rounded or curved.
A door trim that is flush to jamb can lead to unintentional gaps forming over time as the wood dries or the house settles. Installing the door trim slightly away from the jamb edges will help hide the discrepancies. This intentional gap between the trim and edge is called a reveal.
Standard residential door jambs sizes typically measure about 4 9/16 inches wide by 9 9/16 inches tall. This size fits standard wall thicknesses.
The Reveal size is the actual opening inside the frame that the doors will sit in. So in the case of a 2040 x 920mm door, the standard reveal size would be 2055 x 924mm. This allows 15mm height clearance for floor coverings and 4mm clearance width ways.
Choose trim sizes that are appropriate for your room's dimensions. Wider trims work well in larger rooms with high ceilings, while narrower trims are suitable for smaller spaces. Ensure that your trim choices are proportionate to each other, such as crown molding and baseboards.
The most common trim size for books in the US is 6" x 9" (152.4 x 228.6 mm), but you have several other options. Books with a measurement more than 6.12 inches (155.5 mm) or more than 9 inches (228.6 mm) in height are considered large trim sizes.
The most commonly used door trim casing size is 2 ¼ inches in width and ½ thick, although these numbers will regularly go upwards in the ½ inch range. Although it's standard practice to have door and window casings the same size, there is absolutely no real set of factors forcing this.
MYTH: Everything should match
Painting all window and door trim, crown molding and baseboards the same colour provides consistency, but is not a rule. For example, only black baseboards will anchor a room while having only black crown moulding will frame the ceiling and draw your eye up.
Do I Match the Trim Color to the Door Color? Matching the trim to the door creates a subtle and sophisticated look. You can opt for contrasting color combos for the door and trim if you want the door to pop and make a statement.