GLOSSARY OF ARCHITECTURAL MILLWORK

The world of millwork can be a lot of technical jargon. From Architraves to Wainscotting, the sheer number of profiles and trade names can feel overwhelming whether you're a seasoned carpenter or a homeowner planning a renovation.

At CHIPTRIM, we believe the best builds start with clear communication. We’ve compiled this comprehensive glossary to help you navigate the names, the history, and—most importantly—the professional standards of execution. Use this as your definitive field reference to ensure your next project is built to a professional grade.

GLOSSARY F-O

GLOASSARY P-Z

Acclimation: The process of allowing wood to reach equilibrium moisture content with its environment.
- CHIP Tip: Skipping this is the #1 cause of "Whistling Miters." Wood should sit in the room where it will be installed for a minimum 48–72 hours with the HVAC running.
Apron: A horizontal member installed under a window stool.
- CHIP Tip: The apron supports the visual weight of the window. For a professional finish, miter the ends back to the wall (a "self-return") rather than leaving raw end-grain exposed.
Architrave (Header Assembly): The horizontal member above a door or window.
- CHIP Tip: Never flush the header to the casing. Use a staggered reveal—offsetting the architrave by 1/4" or more to create a shadow line that hides out-of-plumb walls.
Astragal (Flat or T-Shape): A vertical moulding attached to the inactive leaf of a pair of double doors.
- Professional Tip: For a professional seal, mortise the hardware into the astragal. If using a T-astragal, ensure it is glued and screwed; it takes the mechanical impact every time the active door closes.

B

Back Band: A rabbeted moulding that wraps the outer edge of a casing to add ornamental relief.
- CHIP Tip: Use a back band to "upsize" standard casing profiles. It’s also the perfect transition point when your casing is thinner than your baseboard—it provides a clean landing for the baseboard.
Base Caps: Decorative moulding installed on top of S4S baseboards flush against the wall.
- CHIP Tip: If your walls are wavy, base cap is your best friend. Because it is thin and flexible, it can be "rolled" to follow the wall line, hiding gaps that a rigid baseboard would leave behind.
Base Shoe: A small profile used to bridge the gap between baseboard and flooring.
- CHIP Tip: Always nail your shoe to the baseboard, never the floor. This allows the floor to expand and contract seasonally without pulling the moulding away or causing cracks.
Baseboard: Applied where the floor and wall meet to protect against kicks and equipment.
- CHIP Tip: The professional way to join baseboard at inside corners is a coped joint, not a miter. A cope stays tight even if the house settles or the wood shrinks.
Batten: A symmetrical pattern used to conceal the line where two parallel boards or panels meet.
- CHIP Tip: When doing Board and Batten, calculate your spacing based on the "center-to-center" distance to ensure the panels look identical across the entire wall.
Bed Mould: Utilized at the wall-to-ceiling junction, often as a smaller alternative to Crown.
- CHIP Tip: Bed moulds are great for tight spaces like closets or small bathrooms where a full Crown profile would feel overwhelming.
Bolection: A heavy moulding that projects beyond the face of a two-tiered construction.
- CHIP Tip: Often used on fireplace mantels or bar counters. The goal is depth—use it to create deep shadow lines that define the piece from across the room.
Brick Mould: Thick exterior casing used to provide a stop for siding or brick.
- CHIP Tip: Always install a metal drip cap above the head brick mould. Without it, water will eventually find its way behind the casing and rot out the framing.

C

Casing: Used to encase door and window frames where they meet the drywall.
- CHIP Tip: The "Reveal" (the amount of jamb left visible) is the hallmark of a pro. A standard 3/16" reveal provides enough "step" to hide the hinge-barrel edge while looking clean.
Cedar: A domestic exotic wood known for its natural aroma and moisture resistance.
- CHIP Tip: If left unfinished, cedar will weather to silver-grey. If staining, use an oil-based product to prevent natural tannins from bleeding through the finish.
Chair Rail: Applied 32–36 inches from the floor to prevent chairs from marking walls.
- CHIP Tip: Level the chair rail to the room’s horizon, not the floor. If you follow a dipping floor, the rail will look crooked against the door casings.
Chamfer Strip: Used where cabinet tops meet walls or as a linoleum cove.
- CHIP Tip: Chamfers are excellent for "softening" sharp 90° outside corners in high-traffic areas.
Coping: Shaping the end of one moulding to fit the face of another (usually at inside corners).
- CHIP Tip: This is the professional standard for inside corners. Unlike miters, a coped joint won't open up when the wood shrinks or the house settles.
Corner Block: Installed at the top corners of doors and windows.
- CHIP Tip: Blocks eliminate the need for complex miters. They are historically accurate for Victorian-style homes and save significant time on large-scale builds.
Corner Jig: The assembly jig This is a dedicated station on your workbench used for glue-ups and fastening. It usually consists of two straight "fences" screwed into a flat surface at a perfect 90°. The verification jig This is a portable sheet of ¾" plywood with a factory-cut (or track-sawed) true 90° corner.
- CHIP Tip: Whether you are building an assembly jig or using a verification sheet, use them for this one reason: They remove the wall from the equation.
Cove: A concave semicircular profile used for inside corners or building up crowns.
- CHIP Tip: Coves are ideal for inside corners. Like Crown, they are best installed by "coping" the ends for a seamless, movement-resistant joint.
Crown (Cornice): Installed at the ceiling-to-wall transition.
- CHIP Tip: When cutting Crown "flat" on a miter saw, you must use specific compound angles based on the "Spring Angle" (38°, 45°, or 52°) of the profile.
Crown Connector Splice Block: Installed to connect crown pieces over a long span.
- CHIP Tip: If you can't get a 16-foot stick, use a splice block as a deliberate design feature rather than trying to hide a scarf joint in the middle of a wall.

D — G

Dentil Moulding: A series of closely spaced rectangular blocks within a Crown assembly.
- CHIP Tip: Derived from the Greek word for "teeth." Be surgical with your layout to ensure you don't end up with a "half-tooth" in a prominent corner.
Door Sill: The horizontal piece forming the bottom of an exterior doorframe.
- CHIP Tip: Ensure the sill is properly flashed and sloped away from the house. Even the best oak sill will rot if water pools.
Douglas Fir: A heavy softwood with a generally straight grain and medium texture.
- CHIP Tip: Fir is notoriously prone to "splintering" when cross-cutting. Use a high-tooth-count finishing blade and a zero-clearance insert on your saw.
Drip Cap: Applied over exterior frames to direct moisture away from window glass.
- CHIP Tip: This is non-negotiable for exterior longevity. It acts as the "umbrella" for your window trim.

THE NUMBERS DON'T LIE.

Knowing the names is the first step. Knowing the math is the finish line.

When you're ready to turn these definitions into a professional Material List and Optimized Cut Plan, we've built the engine to do it for you. No guessing. No waste. Just clean reports.

Last updated: 02/24/2026

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GLOSSARY OF ARCHITECTURAL MILLWORK

B

C

D — G

THE NUMBERS DON'T LIE.

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