Interior Design Industry Glossary

Whether you're a new designer building your vocabulary or a seasoned pro explaining concepts to clients, speaking the language of interior design matters. We put together a glossary of 87 essential industry terms every designer should know — from the basics like FF&E and punch lists to the nuances that trip people up, like the difference between markup and margin (they're not the same thing, and confusing them can cost you thousands). It covers design process phases, business and financial terminology, construction terms you'll hear on every job site, material and finish language that helps you spec with precision, space planning principles, lighting vocabulary, window treatment jargon, and sustainability certifications that are becoming increasingly relevant. Bookmark it, share it with your team, and pull it out the next time a client asks what a rough-in is or why their marble is etching.

Design Process Terms

Schematic Design (SD) — The initial concept phase of a project. Includes big-picture ideas, mood boards, preliminary space plans, and early material direction. This is where the design vision takes shape before any detailed specification work begins.

Design Development (DD) — The phase where the approved schematic concept is refined into detailed selections. Includes final furniture specifications, material selections, fixture choices, and detailed floor plans and elevations.

Construction Documents (CD) — Technical drawings and written specifications that tell contractors exactly how to build the design. Includes dimensioned plans, electrical plans, tile layouts, cabinet elevations, and finish schedules.

FF&E — Furniture, Fixtures & Equipment. Refers to all movable and installable items in a space: sofas, tables, lighting, plumbing fixtures, appliances, window treatments, rugs, and accessories.

Finish Schedule — A master document listing every surface finish in the project by room: paint colors, tile selections, flooring, countertops, hardware, grout colors, and cabinet finishes with vendor, product name, and code.

Punch List — A list of items requiring correction, completion, or touch-up before the project is considered finished. Compiled during a walkthrough near the end of construction. Includes paint touch-ups, hardware adjustments, and damaged items.

Change Order (CO) — A formal written document that authorizes a modification to the original scope of work, including its impact on budget and timeline. Must be signed by the client before work proceeds.

Scope of Work (SOW) — A detailed description of every service, room, deliverable, and exclusion in the project. The foundation of your contract. Defines what you will and will not do.

RFP / RFQ — Request for Proposal / Request for Quote. Documents sent to vendors, contractors, or workrooms requesting pricing, availability, and terms for products or services.

As-Built Drawings — Drawings that reflect the actual built conditions of a space, including any deviations from the original construction documents. Updated during or after construction.

Specification (Spec) — A detailed description of a product including manufacturer, model number, dimensions, finish, color, material, and any custom options. The document that tells a vendor exactly what to provide.

Business & Financial Terms

Retainer — A pre-paid fee that reserves a designer's time and services. Often collected before work begins. May be applied toward the first invoice or held as a deposit until project completion.

Cost-Plus Pricing — A billing model where the client pays the designer's net cost for products plus a predetermined percentage markup (typically 20–35%). The designer's profit comes from the markup.

Markup — A percentage added on top of the wholesale/net cost to determine the client price. Formula: Client Price = Cost × (1 + Markup%). A 30% markup on a $1,000 item = $1,300 client price.

Margin — Profit expressed as a percentage of the selling price (not the cost). Formula: Margin = Profit ÷ Selling Price. A $1,000 cost sold at $1,300 = 23.1% margin. Margin is always lower than the equivalent markup.

Trade Discount — Reduced pricing offered exclusively to licensed or credentialed design professionals by manufacturers and vendors. Typically 20–50% off retail depending on vendor and volume.

COM / COL — Customer's Own Material / Customer's Own Leather. When the client supplies their own fabric or leather (purchased separately) for a furniture manufacturer to use during upholstery.

Net 30 / Net 15 — Payment terms indicating when an invoice is due. Net 30 = due within 30 days of invoice date. Net 15 = due within 15 days. Some vendors offer early-payment discounts (e.g., 2/10 Net 30 = 2% discount if paid within 10 days).

Pro Forma Invoice — An invoice issued before goods are shipped, requiring payment before delivery. Standard practice for custom and trade-only products. The client pays upfront; the product ships after payment clears.

Design Fee — The fee charged for professional design services, separate from product procurement. Can be structured as flat fee, hourly rate, percentage of project cost, or hybrid.

Procurement Fee — A fee charged for the service of sourcing, ordering, tracking, receiving, inspecting, and coordinating delivery of products. Sometimes included in the design fee, sometimes separate.

Allowance — A budgeted dollar amount set aside for a specific category (e.g., $5,000 lighting allowance). Gives the client flexibility within a defined budget. Overages are the client's responsibility.

Deposit — An upfront payment collected before work or ordering begins. Typically 50% of product cost or 30–50% of design fees. Protects the designer against cancellations and covers initial expenses.

Construction Terms

Rough-In — The initial installation of mechanical systems (plumbing pipes, electrical wiring, HVAC ductwork) inside walls, floors, and ceilings before surfaces are closed up with drywall. All rough-in work must be inspected before covering.

Trim-Out — The final installation phase where visible fixtures and finishes are installed: faucets, light fixtures, switch plates, cabinet hardware, door hardware, mirrors, and accessories. Happens after painting.

Load-Bearing Wall — A wall that supports structural weight from above (roof, upper floors). Cannot be removed or modified without a structural engineer's approval and typically a steel beam replacement.

Soffit — A boxed-out horizontal surface that drops below the ceiling plane, typically covering ductwork, plumbing, or structural elements. Can be functional or decorative.

Bulkhead — Similar to a soffit — a boxed-out area of ceiling or wall covering structural or mechanical elements. Sometimes used interchangeably with soffit depending on region.

Backerboard — Cement-based board (e.g., Hardie, Durock) installed as a substrate behind tile in wet areas like showers, tub surrounds, and backsplashes. Provides a waterproof, stable surface for tile adhesion.

Blocking — Extra wood framing installed inside wall cavities to provide solid backing for mounting heavy items: grab bars, floating vanities, wall-mounted TVs, heavy shelving, and large mirrors.

Toe Kick — The recessed area at the base of cabinets, typically 3.5–4" tall by 3" deep. Allows you to stand close to the counter without your toes hitting the cabinet face.

Rough Opening — The framed opening in a wall before the door, window, or appliance is installed. Rough openings are larger than the finished unit to allow for shimming, leveling, and trim.

Furring — Strips of wood or metal attached to a wall, ceiling, or floor to create a level surface, add insulation space, or provide a nailing surface for finish materials. Common in basement finishing.

Subfloor — The structural layer beneath the finished flooring, typically plywood or OSB over floor joists. Subfloor condition determines what flooring can be installed and whether leveling is needed.

GC / General Contractor — The licensed contractor who manages the overall construction project, hires and coordinates subcontractors, pulls permits, and is responsible for the build.

Material & Finish Terms

LRV (Light Reflectance Value) — A measurement of how much light a paint color reflects, on a scale of 0 (pure black) to 100 (pure white). Higher LRV = lighter and more reflective. A dark navy might be LRV 8; a bright white is LRV 85+.

VOC (Volatile Organic Compounds) — Chemicals in paints, stains, adhesives, and finishes that off-gas into the air as the product cures. Low-VOC and zero-VOC products are healthier for indoor air quality.

Honed Finish — A matte or satin finish on natural stone achieved by stopping the polishing process before a high gloss is reached. Hides etching and scratches better than polished but shows water spots more easily.

Polished Finish — A high-gloss, reflective finish on natural stone achieved through extensive polishing. Shows veining dramatically but is more susceptible to visible etching from acids (lemon, wine, vinegar).

Leathered Finish — A textured stone finish created by running a diamond-tipped brush over honed stone. Has a soft, slightly bumpy feel. Hides fingerprints, water marks, and etching better than polished or honed.

Veining — The natural pattern of mineral deposits running through stone (marble, quartzite, onyx). Veining is unique to each slab — always view the actual slab being installed and approve the layout.

Bookmatching — A stone fabrication technique where two adjacent slabs are opened like a book, creating a mirror-image pattern. Used for dramatic feature walls, waterfall islands, and large vanity installations.

Dye Lot — A specific production batch of fabric, wallpaper, tile, or carpet. Colors can vary noticeably between dye lots. Always order enough material from one dye lot to complete the entire project.

Pattern Repeat — The distance between identical points in a repeating fabric or wallpaper pattern. Measured vertically (drop) and horizontally (across). Larger repeats require more material to align the pattern at seams.

Railroading — Running fabric sideways (selvage to selvage instead of top to bottom) to avoid seams on wide applications like headboards, banquettes, or wide drapery panels. Not all fabrics can be railroaded.

Selvage — The finished edge of a fabric roll that prevents unraveling. Typically 1/2–1" wide on each side. Contains manufacturer info, color codes, and pattern alignment marks. Selvage is cut off before use.

Grout Joint — The space between tiles filled with grout. Joint width affects both the look and maintenance of a tile installation. Narrow joints (1/16–1/8") create a seamless look; wider joints (1/4"+) show more grout.

Porcelain vs. Ceramic — Both are clay-based tiles, but porcelain is fired at higher temperatures, making it denser, harder, less porous, and more durable. Porcelain is suitable for all applications; ceramic is best for walls and light-traffic floors.

PEI Rating — Porcelain Enamel Institute rating measuring tile hardness and wear resistance. Scale of 0–5. PEI 0 = wall only. PEI 3 = residential floors. PEI 4 = commercial. PEI 5 = heavy commercial.

Space Planning & Design Terms

Elevation Drawing — A flat, straight-on drawing of a wall or surface as if you are standing directly in front of it. Shows vertical relationships: cabinet heights, tile layouts, art placement, sconce positions, and built-in shelving.

Section Drawing — A drawing showing what you would see if you sliced through a building or cabinet vertically. Reveals internal construction, ceiling heights, floor level changes, and the relationship between stacked spaces.

Sight Line — The visual path your eye travels when entering or moving through a space. The first thing you see when you walk through a door is the primary sight line and should be the focal point or most beautiful view.

Focal Point — The dominant visual element in a room that draws the eye first. Could be a fireplace, a view, a piece of art, a feature wall, or a statement light fixture. Every room should have one clear focal point.

Circulation — The paths people walk through a space. Primary circulation paths need minimum 36" clear width. Secondary paths (around furniture) need minimum 24". Good circulation means no dead-ends or bottlenecks.

Scale — The size relationship between objects and the room they occupy. A small sofa in a large room looks lost. An oversized sectional in a small room feels cramped. Correct scale means the furniture feels proportionally right for the space.

Proportion — The ratio of one element to another. A classic guideline: a sofa should be roughly 2/3 the length of the wall behind it. A rug should be large enough that all major furniture sits on it or all front legs touch it.

Negative Space — The empty space around and between objects. Essential for a room to feel intentional rather than cluttered. Think of it as the breathing room in a design. More negative space = more sophisticated, calm feel.

Vignette — A carefully styled grouping of objects that creates a composed, intentional scene. A console table with a lamp, stacked books, and a sculptural object is a vignette. The art is layering height, texture, and visual weight.

Symmetry vs. Asymmetry — Symmetrical design mirrors elements on both sides of a center axis. Asymmetrical design achieves balance through visual weight without mirroring. Symmetry feels formal, asymmetry feels relaxed.

Visual Weight — The perceived heaviness of an object based on its color, size, texture, and density. Dark, large, solid objects feel heavy. Light, small, transparent objects feel light. Balancing visual weight creates harmony.

Wayfinding — The way people naturally navigate through a space using visual cues: lighting, flooring transitions, sight lines, and furniture arrangement. Good wayfinding makes a space intuitive without signage.

Lighting Terms

Ambient Lighting — General, overall illumination that fills a room. Typically provided by recessed cans, flush-mount ceiling fixtures, or cove lighting. The base layer of a lighting plan.

Task Lighting — Focused light for specific activities: reading, cooking, grooming, working. Provided by under-cabinet lights, desk lamps, pendant lights over islands, and vanity sconces.

Accent Lighting — Decorative or highlighting light that draws attention to a specific feature: art, architecture, shelving, or texture. Typically 3× brighter than ambient in the same area.

Color Temperature — Measured in Kelvin (K). 2700K = warm (yellowish, like candlelight). 3000K = warm white (most common residential). 4000K = cool white. 5000K+ = daylight (bluish, clinical).

CRI (Color Rendering Index) — Measures how accurately a light source renders colors compared to natural light. Scale of 0–100. CRI 90+ is excellent for residential. CRI below 80 makes colors look dull and inaccurate.

Lumens — The measure of total light output from a source. A 60W-equivalent LED is roughly 800 lumens. Kitchens need approximately 30–40 lumens per square foot. Bedrooms need 10–20.

Dimmer — A switch or device that adjusts light output from 0–100%. Essential for flexible lighting moods. Not all bulbs are dimmable — always specify dimmable LED bulbs and compatible dimmer switches.

Recessed Can / Downlight — A light fixture installed flush with the ceiling in a recessed housing. Available in 4" and 6" sizes with various trim styles (baffle, reflector, adjustable).

Sconce — A wall-mounted light fixture. ADA-compliant sconces project no more than 4" from the wall. Best placement for bathroom vanity: at eye level on each side of the mirror.

Chandelier / Pendant — A chandelier is a branched decorative ceiling fixture; a pendant hangs from a single point. Size guideline: room width in feet = chandelier diameter in inches. Hang 30–36" above a dining table.

Window Treatment Terms

Inside Mount — Window treatment installed inside the window frame opening. Creates a clean, built-in look. Requires sufficient frame depth. The treatment cannot be wider than the frame opening.

Outside Mount — Window treatment mounted on the wall or molding above and beyond the window frame. Allows the treatment to be wider and taller than the window, making windows appear larger.

Stacking Width — The amount of wall space drapery panels occupy when fully opened. Typically 15–25% of the total panel width. Panels should stack off the glass for maximum light.

Fullness — The ratio of fabric width to window width in a drapery panel. Standard fullness is 2×–2.5× (the fabric is 2–2.5 times wider than the window). More fullness = richer, more luxurious look.

Return — The portion of the drapery that wraps from the front of the rod back to the wall, blocking light at the sides. Standard return is 3.5–4". For light-blocking, returns should meet the wall completely.

Break / Puddle — The amount of fabric resting on the floor. Clean break = just touching. 1" break = slight bend. Puddle = 2–6" pooling for a formal, luxurious look.

Blackout vs. Room Darkening — Blackout blocks 99%+ of light with an opaque liner. Room darkening significantly reduces light but does not block it completely. True blackout also requires full-coverage mounting with side channels or returns.

Motorization — Electronic operation of window treatments via remote, wall switch, app, or smart home integration (Lutron, Somfy, Hunter Douglas PowerView). Requires hardwired, plug-in, or battery power source.

Sustainability & Wellness Terms

LEED — Leadership in Energy and Environmental Design. A green building certification by the USGBC. Projects earn points across energy, water, materials, and air quality and achieve Certified, Silver, Gold, or Platinum levels.

WELL Certification — A building certification focused on human health and wellness. Evaluates air, water, nourishment, light, movement, thermal comfort, sound, materials, mind, and community.

Biophilic Design — A design philosophy incorporating natural elements to strengthen the human connection with nature: natural light, plants, natural materials, water features, views of nature, and organic forms.

Cradle to Cradle (C2C) — A product certification evaluating material health, material reutilization, renewable energy, water stewardship, and social fairness. C2C products are designed for continuous life cycles, not disposal.

FSC Certified — Forest Stewardship Council certification indicating that wood products come from responsibly managed forests. Look for FSC-certified hardwood flooring, cabinetry, and millwork.

Greenguard / Greenguard Gold — Certification that a product meets strict chemical emission limits for indoor air quality. Greenguard Gold is approved for schools and healthcare environments.

Embodied Carbon — The total greenhouse gas emissions generated during the manufacturing, transportation, installation, and disposal of a building material. Lower embodied carbon = lower environmental impact.

Adaptive Reuse — Repurposing an existing structure or material for a new function rather than demolishing and rebuilding. Examples: converting a warehouse to a loft, reusing antique doors, repurposing vintage furniture.