Timeline Windows & Patio Doors
Timeline Home

Glossary

Terminology used in the building industry can be confusing at times. For those instances, we’ve assembled a group of the terms that we use often with the hope that it’ll help you understand our products and what we offer.

Below you’ll find some brief descriptions of some of the more common terms referenced by Timeline for our window and patio door lines.

  • A
  • B
  • C
  • D
  • E
  • F
  • G
  • H
  • I
  • J
  • K
  • L
  • M
  • N
  • O
  • P
  • Q
  • R
  • S
  • T
  • U
  • V
  • W
  • X
  • Y
  • Z

AAMA

AAMA (American Architectural Manufacturers Association) is the source of performance standards, product certification and educational programs for the fenestration industry.

Accessory Groove

A channel on the exterior of a Timeline vinyl, Lincoln aluminum clad (Distinction Collection) or vinyl clad (Harmony Collection) product line designed to accept exterior trim and accessory options.

Aluminum-Clad Window

A window with a wood construction interior and an exterior of extruded aluminum. Has a factory-applied finish to deter the elements.

Anchor Strip

The board around a window frame nailed to house framing. It also serves as windbreak. In newer windows, the anchor strip may be plastic or metal.

Angle Brace

The wood members nailed across the window frame at the upper corners while the frame is in a squared position. This is done in order to maintain it’s squareness before installation.

ANSI

American National Standards Institute.

Apron

An inert gas with low thermal conductivity.  This is used in the air space on our Triple pane, LoE² and LoĒ³-366™/Neat® insulated glass units.

Argon

An inert gas with low thermal conductivity. This is used in the air space within our LoE² and LoE366 insulated glass units.

Astragal

On a two-wide swing door, this vertical member is situated in the center where the two panels come together to cover up the weatherstripping.

Awning Window

An operable window with a sash that is hinged at the top.

 

Backband

The millwork trim around the outside edge of exterior casing. This is a common wood window option and is commonly available as a one-piece backband exterior trim and a 2-Piece Backband option.

Balance

The hardware used for counterbalancing the sliding sash in a double-hung window. This allows the sash to be raised and left in any given position.

Bay Window

A set of windows that project out from the wall of the structure. Timeline offers a 30° and 45° angle bay (which represents the angle the windows come out of the opening) for the Casement and Double Hung window lines. Also see Bow Window.

Bottom Rail

The bottom horizontal member of a window sash.

Bow Window

A set of 4, 5 or 6 mulled windows that project from the wall in the shape of a gradual arc.

Brickmould

The exterior casing that surrounds the window or door which covers the gap between the frame and the home.

 

Casement Window

A window unit with a sash that is hinged on the side of the sash. Timeline offers a crank-out and radius version. Typical configurations include: 1, 2, 3, and 4 wide units, triple picture units, bows, bays and matching transoms.

Casing

The trim which covers the gap between the window or door frame and the wall of the home.

Check Rail (Meeting Rail)

The area of a double-hung, single-hung or sliding window where the sash come together-typically in the center of the window. Check Rails are reinforced with aluminum, have an interlock and are weather-stripped for energy saving performance.

Center of Glass “U” Value

The amount of thermal transmittance at the center area of the glass unit to within 2 1/2" of the framing. The “U” value in this area is affected by the insulated glass make-up. (i.e. the glass type and thickness along with the airspace type and thickness)

CFM

Cubic Feet of Air per Minute, the measurement of air taken at a specified pressure during certification testing. Usually the CFM is measured per lineal foot of weatherstripping or per square ft of frame area.

Clear Opening

The opening, in width and height, of a door panel or window sash that allows a person to climb through in case of an emergency. Although local codes may vary, typical egress clear opening requirements are 5.7 square feet with a minimum of 20” in width and 24” in height and a sill height not exceeding 44” above floors.

Condensation

A film of water droplets: tiny drops of water that form on a cold surface such as a window when warmer air comes into contact with it. Condensation on a window is an indicator of high humidity levels in the home.

 

Double Hung Window

A window which has two sash which meet at a checkrail. Both sash move vertically up and down and can be tilted or removed for easy cleaning.

Drip Cap

A horizontal extrusion that sits on the top of a window or patio door at exterior.  This trim piece diverts water away from the top and protects mull joints.

 

Edge of Glass “U” Value

The amount of thermal transmittance at an area of the glass unit 2-1/2" from the framing. The “U” value in this area is affected by the insulated glass make-up including the spacer type and the conductivity of the framing.

Egress

An opening that provides a continuous and unobstructed exit from a building. Although local codes may vary, typical clear opening requirements are 5.7 square feet with a minimum of 20” in width and 24” in height and a sill height not exceeding 44”.

Egress Hardware

The hardware used on a Casement Window to allow the sash to open further for a larger clear opening width in order to better meet clear opening requirements.

Emissivity

A percentage of the amount of heat that radiates through the low “e” coating.

Extension Jamb

An interior trim board used to increase the jamb depth of a window frame to fit any given thickness of wall.

 

Fenestration

Products that fill openings in a building envelope designed to permit the passage of air, light, vehicles or people.

Fire Rated Glass

Glass with a fire-endurance rating.

Flashing

Material used for controlling, redirecting or preventing water from entering a structure.

French Casement Window

A casement with two crank-out sash hinged to open in the middle.

 

Glazing

The installation of glass in a window opening.

Glazing Bead

The molded trim that holds the glass in the sash of the window or door.

Glider Window

A window which has two sash which meet at a checkrail. The operable sash moves horizontally left to right and can be removed for easy cleaning. Available also as a Triple Glider with two operable sash flanking a center sash in one frame. Also see Slider Window.

 

Head

The upper frame member on a window or patio door.

Header

The support piece above a window or patio door opening which transfers the weight of the building above the product to the supporting wall structure on each side of the window or door.

Head Flashing

Flashing installed in a wall over a window to prevent water infiltration.

Hybrid Window

A window unit utilizing a primed frame with either an aluminum clad or vinyl clad sash.

 

Insulated Glass

Two panes of glass with an enclosed air space between them.

 

Jamb

A vertical member of the window frame. Can also refer to the horizontal member at the top of a window frame, as in Head Jamb and Window Jamb.

Jamb Depth

The width of the window frame from inside to outside.

 

KD or Knocked-Down

Patio doors which require the manufactured frame and panels to be assembled on the job site due to their size.

 

Lite

The light divisions within the sash of a window or patio door. A sash with no grids would be 1 lite.

Low E

Low Emittance coating that has a reduced ability to radiate heat energy; when facing an air space this property reduces the amount of heat transfer across the space.

 

Meeting Rail

One of the two horizontal members of a double hung or single hung window where the sash come together.

Meeting Stile

The vertical sash member on the slider or triple slider window where the sash come together.

Mullion

The vertical or horizontal member between window or patio door units that have been joined together.

Muntin Bars

A generic reference for grills/grids on a window or patio door.

 

Nailing Flange

The vinyl strips around the window and door unit used to install the unit into the rough opening. Aluminum clad units have nailing flange applied to the frame, while the Timeline vinyl and W-V series have an integral nailing flange as part of the frame itself.

NFRC

National Fenestration Ratings Council. An association representing the fenestration, glazing, building industries. Also represented on the board are design professionals/specifiers, state energy offices, utilities and the consumer interest groups. One of their main goals is to establish a national rating system for window products and standards for calculating energy efficiency.

 

Operable Window

A window which can be opened for ventilation.

 

Parting Stop

The vertical piece on a Double Hung head jamb or Glider side jamb that separate the sash.

Picture Window

A large fixed window also called a studio window.

 

Queen Anne Grids

A grille configuration style that will utilize 2 horizontal and 2 vertical bars in a layout that will feature 3” or 4” squares in the 4 corners of the window or patio doors.

 

R Value

The opposite or reciprocal of the “U” Value, the amount of resistance a material or airspace has to thermal conductivity. The higher the “R” value, the less heat is transmitted through the material. (“R” Value = 1/”U” Value or “U” Value = 1/”R” Value).

Rail

The horizontal member of a window sash.

 

Sash

The stiles and rails framework holding the glass.  These are then installed within the frame of a window.

SDL Bars

Also known as simulated divided lites, these muntin bars are used on a sash to replicate the look of a true divided lite window or door. Units have one lite of glass with bars in various widths adhering to the glass on the interior and exterior of the glass. It is common to have an interior ‘shadow’ bar in mill finish or bronze in color.

Shading Coefficient

The ratio of solar heat gain through a glazing system to the solar heat gain through a single lite of 1/8” (3mm) glass.

Sidelite

The narrow component mulled adjacent to a patio door. Timeline offers standard or custom size sidelite options.

Sill

The horizontal member at the bottom of the window frame or patio door.

Single Hung Window

A window similar in look to a double hung window, but only the bottom sash is operable – moving up and down.

Slider Window

A window which has two sash which meet at a checkrail. The operable sash moves horizontally left to right and can be removed for easy cleaning. Available also as a Triple Slider with two operable sash flanking a center sash in one frame.  Also see Glider Window.

Studio Window

A large fixed window also called a picture window.

 

Tempered Glass

Special heat-treated, high-strength safety glass which shatters into pebble-sized particles and not in slivers.

Transom

A fixed window placed directly above a window or patio door.

 

U-Factor

A measurement of how well a product prevents heat from being transmitted. The lower the U-factor, the better the product’s insulating value.

UV Transmittance

The amount of Ultra Violet rays allowed to transmit through glass, expressed as a percentage. The lower the transmittance, the better the product will guard interior surfaces from sun fade.

 

WV Series

A window with a wood construction interior and an exterior of extruded vinyl for a low-maintenance exterior. The vinyl color is available in white, sandstone and adobe colors only.