Door and Window Types, Components, and Trade Terminology

Why Terminology Matters

Before you hang your first door or set your first window, you need to speak the same language as your foreman, your inspector, and the manufacturer's installation instructions. Misreading a term on a cut sheet or calling out the wrong hand of a door can mean a wasted trip to the supply house, a failed rough opening, or a callback that costs you money and reputation. This lesson builds the vocabulary you will use every day on the job and throughout your NCCER Carpentry modules.

Door Types and Their Uses

Interior hollow-core doors have a cardboard or honeycomb core and a thin wood or hardboard face. They are lightweight and inexpensive, used for bedroom and closet openings where sound control and security are not priorities.

Interior solid-core doors contain a continuous wood or composite core. They are heavier, provide better sound isolation, and are often specified for home offices, media rooms, or wherever fire-rated assemblies are not required but noise reduction is valued.

Exterior insulated doors — whether steel, fiberglass, or solid wood — have an insulated core that resists heat transfer. Steel and fiberglass doors are dimensionally stable and resist warping; wood doors require more maintenance but are traditional in appearance.

Sliding doors (also called bypass or patio doors) ride on a track and do not swing. They are common for closets and rear patio openings. No swing clearance is needed, which saves floor space.

Pocket doors slide into a wall cavity. The rough opening must accommodate the pocket frame in addition to the door width.

Bifold doors fold at a center hinge and are common for closets where a full swing is impractical.

The Hand of a Door

"Hand" describes which side a door is hinged and which direction it swings. Stand on the side the door swings toward (the pull side). If the hinges are on your left, the door is left-hand. If the hinges are on your right, it is right-hand. For doors with a key or lever that requires a special strike — where the door swings away from you — the designation becomes left-hand reverse or right-hand reverse. Ordering the wrong hand means the door cannot be installed without reframing or returning the unit.

Parts of a Prehung Exterior Door Unit

A prehung unit arrives with the door already mounted on its hinge jambs and the complete frame assembled. Key components:

• Head jamb — the horizontal top member of the frame.
• Side jambs — the two vertical members; the hinge jamb carries the hinges, the strike jamb receives the latch.
• Door stop — a narrow strip nailed or milled to the inside face of each jamb; the door closes against it.
• Sill — the sloped bottom member that sheds water away from the structure.
• Threshold — the transition piece at the floor level, often adjustable, that closes the gap between the sill and the finished floor.
• Weatherstripping — compressible or sliding seals at the head, sides, and sometimes the bottom (door sweep) that block air and water infiltration.
• Rough opening (RO) — the framed opening in the wall; typically 2 inches wider and 2 inches taller than the nominal door size to allow for the frame, shims, and adjustment.
• Finish opening — the clear opening inside the installed frame that the door occupies.

Window Types and Components

Double-hung windows have two sashes that slide vertically. Both sashes can open, which allows hot air to escape from the top while cooler air enters at the bottom. The upper sash and lower sash each ride in a channel on the jamb.

Single-hung windows look similar, but only the lower sash operates; the upper sash is fixed.

Casement windows are hinged at the side and crank outward. They seal tightly when closed, giving them good energy performance.

Awning windows are hinged at the top and open outward from the bottom. They can remain open during light rain.

Fixed windows do not open. They are used for light and view only and typically have the best air-leakage ratings because there are no operable seals.

Sliding windows move horizontally on a track, similar to patio doors scaled down.

Window Parts

• Frame — the outer structure: head, sill, and two side jambs.
• Sash — the inner frame that holds the glazing and moves (or is fixed).
• Glazing / lite — the glass unit.
• Muntin — a true structural bar that divides a sash into multiple small lites of glass.
• Grille / grid — a decorative bar applied to or sandwiched inside the glass to simulate muntins on an insulated glass unit.
• Mullion — the vertical structural member between two adjacent window units in a multi-unit assembly.
• Sill horn — the portion of the sill that extends beyond the side jamb on each end; it sits in the rough opening and is trimmed or cased over.
• Rough opening — same concept as for doors; the framed wall opening sized to accept the window unit plus shimming clearance.

Energy Performance Labels

NFRC (National Fenestration Rating Council) labels appear on certified windows and exterior doors. Two ratings you must be able to read:

• U-factor — the rate of heat transfer through the product; lower numbers mean better insulation.
• Solar Heat Gain Coefficient (SHGC) — the fraction of solar energy that passes through; lower values block more heat, which benefits cooling-dominated climates.

Local energy codes often set maximum U-factor and SHGC values by climate zone. Always verify compliance with the applicable energy code before ordering.

Safety Reminders

Door and window units are heavy and awkward. Use a helper or a panel cart when moving prehung units. Wear safety glasses when cutting or trimming jambs, and work gloves when handling glass edges or metal door skins. Inspect all glass lites for cracks before installation — a cracked insulated unit cannot be repaired on site and may be a laceration hazard during handling.