Drywall and painting have their own vocabulary, and using the wrong term gets you the wrong answer from a contractor or a supplier. Sheen is not the same as finish. Mud is not the same as joint compound. Prime is not the same as seal. This glossary owns the terms so the how-to and buying guide pages can stay at the system level. For the broader drywall and painting context, the drywall overview, the drywall vs plaster comparison, and the painting cost guide are the anchor pages.
Drywall Terms You Need to Know
| Term | Definition | Why it matters |
|---|---|---|
| Drywall | Gypsum board, also called sheet rock or wallboard | Primary wall and ceiling surface |
| Joint compound | Mud used to cover seams and nail holes | Affects finish quality and crack resistance |
| Tape | Paper or mesh tape embedded in joint compound | Prevents cracks at seams |
| Cement backer board | Cementitious board used under tile | Waterproof substrate for wet areas |
| Type X | Fire-rated drywall, usually 5/8 inch | Required by IRC for garages and furnace rooms |
| Unfinished drywall | Drywall before tape, mud, and paint | Shows seams and imperfections until finished |
| Skim coat | Thin layer of joint compound over entire wall | Creates smooth surface for high-gloss paint |
Paint Terms You Need to Know
| Term | Definition | Why it matters |
|---|---|---|
| Sheen | Reflectivity of dried paint, from flat to high gloss | Decision: flat hides flaws, gloss is washable |
| Primer | Base coat that seals and promotes adhesion | Essential for new drywall and stain blocking |
| Sealer | Coat that blocks stains or moisture | Prevents tannin and smoke stains from bleeding |
| Undercoat | Intermediate coat between primer and finish | Improves coverage for dramatic color changes |
| Topcoat | Final finish coat, usually 2 coats | Provides color, sheen, and durability |
| Eggshell | Low-luster sheen, more washable than flat | Standard for living rooms and bedrooms |
| Satin | Medium sheen, durable and washable | Standard for kitchens, bathrooms, trim |
| Semi-gloss | High sheen, very washable | Standard for trim, doors, cabinets |
| Scuff resistant | Paint formulated to resist marks and cleaning | Important for high-traffic areas and kids’ rooms |
Tool and Material Terms
| Term | Definition | Use |
|---|---|---|
| Roller nap | Thickness of roller cover fabric | 1/4 inch for smooth, 3/8 inch for textured |
| Edger | Brush with guard for cutting in | Cuts in at ceiling and corners |
| Taping knife | Flexible blade for applying joint compound | Widths 4, 6, 10 inches common |
| Sponge tip applicator | Foam tool for texture blending | Smooths joint compound ridges |
| Sand pole | Extendable pole for sanding | Sands walls and ceilings safely |
For owners still learning the trade, the drywall tape and mud page and the drywall repair guide show these terms in practice. For the painting decision tree, the paint sheen comparison maps sheen to room.
Frequently Asked Questions About Drywall and Painting Terms
What is the difference between primer and sealer? Primer promotes adhesion. Sealer blocks stains. You need primer on new drywall. You need sealer over stains or smoke damage.
Is joint compound the same as mud? Yes. Mud is the short name for joint compound.
What sheen is best for ceilings? Flat or eggshell. Flat hides imperfections. Eggshell is easier to clean.
Do I need to sand between coats? Light sanding between coats improves adhesion and smoothness. Not required for most premium paints.
What is skim coating? Applying a thin layer of joint compound over the entire wall to create a perfectly smooth surface.
