Common Building and Construction Terms

Here you will find easy to understand definitions of construction terms to help you understand those various building products and installations. Be armed with knowledge about terms used for door and window installation and much more.


A molding or strip that is attached to the inactive door. Its purpose is to cover or close the gap between a pair of doors.

Back Cut

Cutting a little more off the back side of the cut so that there is less material towards the rear edge of the trim piece.


The trim applied where the wall meets the floor. This moulding is usually wider and typically slightly thinner than the door casings.

Bi-Fold Door

Two doors connected with hinges, enabling them to fold together. Typically attached to a track and hanger fastened to the header. We recommend using a Cased Opening w/Stop Frame. This hides track and hangers.

Bi-Pass Door

Doors that slide past each other within the door frame, as opposed to being hinged.

Bottom Plate

Also commonly known as sole plate. The framing member that connects to the wall studs and then in turn is connected to the floor.

Brick Moulding

Exterior trim typically applied to a door or window. This can be of wood or other composite material.

Butt Hinge

A hinge that is mortised flush into the edge of the door and jamb. A hinge composed of two plates attached to abutting surfaces of a door and door jamb and joined by a pin.


Moulding or trim typically applied around doors and windows. A standard milled door casing is 2-1/4" wide.

Cripple Stud

A stud that is used above a door or above or beneath a window. It is placed in sequence with the on center spacing of other studs in the wall. Example 16" on center. This allows for continuous connection of interior or exterior wall sheathing.

Door Clearance

A broad term, it can refer to the space between the top of the door and header rabbet or bottom of the door and finished floor. It can also refer to the space between the door and the jamb. 

Double Acting Door

A door hinged that swings both inward and outward.

Drip Cap

A piece of metal bent to be tucked under the siding, up the wall  and over an exterior opening such as a door or window. This metal is used to direct water away from the interior of the building.

Embossed Door

Pressing a hardware preparation in the frame with a punch press.

Extension Jamb

A piece of wood that is used to widen the frame of a door or window. Normally applied to the inside of a window or door frame so casing or trim can be applied to a wider wall.

Finger Joint

The finger joint is made by cutting a set of complementary rectangular or V cuts  in two pieces of wood, which are then glued. To visualize a finger joint simply interlock the fingers of your hands at a ninety degree angle; hence the name "finger joint." It is stronger than a butt or lap joint, and often forms part of the overall look of the piece.

Fire-Rated Door

A door that resists the passage of fire and heat. Required by Building Codes in certain areas of a building -between the garage and the house for residences- and takes a certain number of minutes to burn; usually 20, 60, or 90 minutes.

Fixed Transom

Panel or glass lite above door opening which is inoperable.

Flush Door

 A door without any panels or raised moulding applied. A door consisting of a flat veneer.

French Door

An interior or exterior door with glass in which both doors operate. Both hinges are on the outer portion of the jamb and the knobs or handles are in the middle.

Gable Wall

The wall of a house that is peaked at the roof. Not the eave side. This wall is normally non load bearing.


The plates and pins used to attach the door unit to the frame.

Hinge Binding

A term used to describe when a door is over shimmed (a turning or tow-in of the jambs) causing the hinges to make contact prior to the door fully closing. Usually a spring back of the door just prior to fully closing.

Hinge Jamb

Vertical member of frame prepared for installation of hinges.


Term used to designate direction in which door swings.


A term describing the swinging direction of a door as one stands on the side of the door from which security is desired, namely the outside.


The structural support above a door or window. Thickness and size depends on the loads the header supports and building codes.

Head Jamb

The jamb or frame that runs horizontally across a door or window.

Jack Stud

Wall stud that fits under the header, helps to support the header load down to the floor system or foundation. The stud closest to the inside of a door or window opening. Also known as lap stud.


The boards or frame that hold or contain doors and windows in place. The outer frame work of a door or window.

Jamb Depth

Measure of the depth or width of the jamb, perpendicular to the door when closed. The width of the entire wall including framing, interior and exterior wall coverings. A typical interior wall thickness is 3-1//2" stud plus a layer of drywall on each side of 1/2" equals 4-1/2" thick. This normally uses a 4-9/16" jamb to allow for imperfect walls.

King Stud

The continuous stud from bottom to top plate that connects the header across a rough opening.


Perfectly horizontal. Using a level on a horizontal plane, such as a floor.

Low E Glass

Low E stands for “low emissivity,” a microscopic metallic coating on glass that helps keep your house warmer in the winter and cooler in the summer.


Medium Density Fiberboard


A rectangular hole cut into a piece of wood to accept a tenon or a door latch plate. (see tenon)


Small pieces which separate the glass from the window frame in divided light or grille style patio door.


Word often misused to refer to muntins. The only difference between Muttins and Mullions are that Muttins visually separate glazed areas, where Mullions structurally separate them.

Panel Doors

Door constructed with panels, stiles, and rails on a wood surface. Combining several smaller components (stiles, rails, loose-fitting panels) into one door allows panel doors to maintain their shape while expanding and contracting with weather and temperature changes.


Perfectly vertical. Using a level on a vertical plane.

Prehung Door

A precut and assembled unit consisting of a door with the door hung on hinges in a wood frame.

Raised Panel Door

A door panel on which the edges have been contoured or shaped to provide an aesthetically appealing, three-dimensional effect.

Rim Joist

The outside perimeter of the floor system that usually rests on the foundation. The cavity created where the floor joist butt into the exterior rim joist.

Rough Opening

The opening where a door or window will fit. Usually larger than the unit to allow room for leveling, plumbing and squaring of the door or window being installed.


Refers to the resistance a door or window has to thermal transfer or heat flow. Expressed as a number such as R-3.1


The bottom portion of a door or window. Commonly sloped to facilitate drainage away from the interior of a building.

Solar Heat Gain

The percentage of heat gained from both direct sunlight and absorbed heat. The smaller the number, the greater the ability to reduce solar heat gain. Also known as Solar Heat Gain Coefficient (SHGC).


The flooring material that is applied directly to the floor joist.

Tempered Glass

A piece of glass that has been put through a special heat-treated tempering process, allowing the glass to crumble under severe impact into small pieces to reduce the chance of injury. See where this is code required.


A protrusion from a board that fits into a matching mortise to form a joint.  


Also known as a sill. A piece of wood or metal connecting the bottom frame of a door.

Top Plate

The framing member in which the wall studs are connected at the upper most part of the wall. Most codes require the top plate be doubled to carry bearing roof or floor loads.


The amount of heat transferred through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality. R value is the reciprocal of U-value.

Venting Door

A door that is made with a solid panel as the bottom half and a screen for ventilation as the top half. Also called a combination door.

Wood Composite

A wood-based compound utilizing wood fibers, reconstituted wood or other wood derivative. This material is then used to make wood fiber interior and exterior doorskins.

Wood Edge Steel Door

An exterior steel skin door in which the latch, hinge, top and bottom have exposed wood edges.

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