Window & Door Trim Casing Shop Drawings: Profiles, Reveals, and Installation Details

Window and door trim looks simple on the wall — a few pieces of molding around an opening. But when you're fabricating custom trim from scratch, or installing a system that integrates with wainscoting, coffered ceilings, or a custom plinth block system, the shop drawings have to resolve a lot more than they appear to. Profile dimensions, reveal setbacks, corner conditions, and base molding intersections all need to be shown before the first cut.

In my experience, trim casing is one of the most underspecified millwork categories on commercial and high-end residential projects. The architect shows the profile in section once, notes it on the schedule, and assumes the fabricator will work out all the intersection details. The fabricator who gets clear shop drawings with those details resolved is the one who installs clean, tight joints. The one who doesn't spends time on-site figuring out conditions that should have been resolved at the drawing table. Our millwork shop drawing services include all the intersection and corner details that typical architectural drawings omit.

Trim Casing Profiles: What the Drawing Must Show

The profile cross-section is the most critical drawing for any custom casing — it's what the router operator programs and what the QC check uses to verify the finished piece. A complete profile cross-section must include:

• Overall width and thickness — finished dimensions, not stock dimensions before routing
• Each curve or flat element dimensioned — ovolo radius, cove depth and width, bead diameter, all from the back face as the reference datum
• Back relief or hollow back note — whether the back of the casing is routed hollow for a tighter fit against the wall; this is standard on wide trim over imperfect wall surfaces
• Material specification — painted (MDF, poplar, finger-jointed pine) or stained (oak, maple, cherry)
• Scale — 3"=1'-0" minimum; full-size (1"=1") preferred for complex profiles

The three most common casing profiles in commercial and residential millwork:

Colonial (curved). Features one or more ovolo (quarter-round) profiles with a flat fillet between curved elements. The most widely used residential profile. Width typically 2-1/4"–3-1/2" finished. The curved face means inside corner connections must be coped, not mitered — show the cope detail on the drawing.

Craftsman (flat). Flat face with a square or slightly beveled edge; sometimes with a routed step at the door jamb edge. Width typically 2-1/2"–3-1/2". Inside corners miter cleanly because both pieces are flat — easier to install than curved profiles. The signature of Arts and Crafts, contemporary, and transitional interiors.

Traditional/built-up. Multiple separate molding pieces assembled in layers — a flat board with applied back band, cap molding, and bead. Each component must be drawn separately with its own cross-section, plus an assembly elevation showing how the pieces stack.

Reveal Dimensions: Small Number, Big Consequence

The reveal is the setback between the casing face and the edge of the door or window jamb. Standard residential reveal is 3/16"–1/4". Craftsman style often uses 3/8"–1/2" as a design feature. This number seems minor, but it controls:

• The overall width appearance of the casing (a larger reveal makes the casing look narrower relative to the opening)
• Whether the door stop and weatherstripping is visible from the front (a small reveal hides it better)
• The exact cut length of each casing piece — head casing and side casings must be cut to account for the reveal at each corner

The reveal must be dimensioned explicitly on the elevation drawing for every door and window type. "Standard reveal" is not a drawing note — the dimension must be stated.

Base Molding Intersection at Door Casings

The intersection of base molding and door casing is one of the most common detail problems in trim work. Three solutions, each requiring its own drawing detail:

Plinth block. A square or rectangular block at the base of the door casing that's wider than both the base molding and the casing, and taller than the base molding. Both the base and the casing terminate against the plinth block face with a butt joint — clean, simple, forgiving of minor installation variation. The drawing must show plinth block dimensions (width must exceed casing width by at least 1/4" on each side; height must exceed base molding height by at least 1/4") and the projection from the wall.

Mitered base return. The base molding terminates against the casing with a coped or profiled end return. Works cleanly with flat or near-flat base profiles. For curved colonial or ogee base profiles, the end return must be machined to match the profile, which requires it to be shown in the drawing at large scale.

Rosette block. A decorative corner block at the top corners of the door casing where the head and side casings meet, plus a plinth at the base. Eliminates all miter joints. Common in Victorian and traditional interiors. The rosette profile must be drawn in plan, elevation, and cross-section.

Corner Conditions: Inside and Outside

Inside corners (where two walls of a room meet) require a coped joint on the second piece of base molding — one piece runs full, the second is back-cut to the profile of the first. The drawing should show a plan view detail of the coped joint at inside corners for any non-standard base profile.

Outside corners (at projecting corners, columns, or pilasters) use a 45° miter. For flat trim, this is straightforward. For curved profiles, the miter must be cut on both pieces identically — a dimension error causes an open joint that's visible. The drawing should show the outside corner condition in plan view with the miter angle called out.

Window Stool and Apron: The Base of the Window

The window stool (the horizontal sill piece that projects into the room at the base of the window) and the apron (the trim piece below the stool) are often omitted from drawings that focus only on the side and head casing. A complete trim drawing package includes:

• Stool elevation: showing stool width (projection beyond casing face — typically equal to the casing projection plus 1/16" overhang), length (extends past casing to match the side casing reveal), and thickness (typically 3/4"–1-1/8")
• Stool return detail: the end of the stool turns back to the wall — a flat return or a routed profile match; this must be shown in plan view
• Apron profile and height: typically the same profile as the head casing, same width; height dimension from stool bottom to apron bottom must be stated

For more on what a complete architectural millwork drawing package should contain, see our millwork shop drawing checklist. If your trim scope includes a coffered ceiling that coordinates with the window casing details, also see our guide on coffered ceiling shop drawings for how ceiling and wall trim intersections are drawn.

When Trim Casing Needs Full Shop Drawings

Not every trim job requires shop drawings. Standard stock profiles on a simple residential interior don't need them. Shop drawings for window and door trim are warranted when:

• The profile is custom-routed from scratch rather than selected from a catalog
• The project spec references AWI standards (which require drawing documentation)
• The trim integrates with wainscoting, coffered ceiling beams, or other architectural millwork at shared corners
• There are multiple trim profiles that must coordinate — head casings with applied pilasters, base molding that transitions between rooms
• The project is commercial and requires a GC submittal package

See our millwork drawing rates for architectural trim work, including per-profile and per-room drawing options.

Frequently Asked Questions