Click on the links below
 to learn more about our
 industry terms.

 

Window Terminology    

When deciding on a contractor to do work on your home it is always helpful to be able to understand their unique language. The glossary of terms that follows provides some of the common terms associated with windows that you may encounter when reviewing companies and products.

WINDOW TERMINOLOGY

Astragal
The center member of a double door, which is attached to the fixed or inactive door panel.
 
Awning window
A window unit in which the bottom of the sash swings outward.
 
Bay window
A composite of three windows, usually made up of a large center unit and two flanking units at 30- or 45-degree angles to the wall.
 
Bow window
A composite of four or more window units in a radial or bow formation.
 
Brickmold
A type of external casing which frames windows and doors.
 
Casement window
A window unit in which the single sash cranks outward, to the right or left.
 
Casing
Molding of various widths, thickness and shapes applied to the framework of window and door units.
 
Check rail
On a double-hung window, the bottom rail of the upper sash and the upper rail of the lower sash, where the lock is mounted.
 
Circlehead
A generic term referring to any of a variety of window units with one or more curved frame members, often used over another window or door opening.
 
Cladding
An aluminum material locked to the outside faces of many window products and exterior trim to provide a durable, low-maintenance exterior surface.
 
Clerestory window
A venting or fixed window above other windows or doors on an upper outside wall of a room.
 
Cottage double-hung
A double-hung window in which the upper sash is shorter than the lower sash.
 
Dormer
A space which protrudes from the roof of a house, usually including one or more windows.
 
Double-hung window
A window unit that has two operable sashes which move vertically in the frame.
 
Drip cap
A molding placed on the top of the head brickmold or casing of a window frame that diverts water from entering the window from the top.  This trim bridges the gap between the window trim detail and the siding material..
 
Dual durometer
A material that has two or more levels of flexibility. An example is the weatherstripping used between the frame and sash of a casement window.
 
Extrusion
A form produced by forcing material through a die. Window frames are clad with extruded aluminum.
 
Fenestration
An architectural term referring to the arrangement of windows in a wall. From the Latin word, "fenestra," meaning window.
 
Fixed
Non-venting or non-operable.
 
Flashing
A thin strip of metal or synthetic material that diverts water away from a window or skylight.
 
Foam Spacer
Foam material placed in the airspace of the insulating glass in Pella Architect Series® windows to enhance the appearance and improve the performance of the window.
 
Frame
The enclosure in which window sash or door panels are mounted.
 
French hinged door
Hinged door(s) which have wider panel members around the glass.
 
French sliding door
A sliding door which has wider panel members around the glass, giving the appearance of a French hinged door.
 
Glazing
Glass in a window or door; the act or process of fitting with glass.
 
Glazing stop
The part of the sash or door panel which holds the glass in place.
 
Grille
A term referring to windowpane dividers or muntins, usually a type of assembly which may be detached for cleaning.
 
Head
The main horizontal member forming the top of the window or door frame.
 
Header
A horizontal framing member placed over the rough opening of a window to prevent the weight of wall or roof from resting on the window frame.
 
Hopper
A window unit in which the top of the sash swings inward.
 
Insulating glass (IG)
A combination of two or more panes of glass with a hermetically sealed air space between the panes of glass. This space may or may not be filled with an inert gas, such as argon.
 
Integral Light TechnologyTM
Patented technology used in Pella Architect Series® products in which foam spacers are inserted between the panes of insulating glass.
 
Jamb
The main vertical members forming the sides of a window or door frame.
 
Jamb liner
In a modern double-hung window, the track installed inside the jambs on which the window sashes slide.
 
Knocked down (KD)
Unassembled window or door unit.
 
Low-E glass
Low-E is a glass coating comprised of microscopic metal particles that lessens the transmition of light into the dwelling thus resulting in a cooler interior temperature.  Low-E glass also results in less fading of items on the interior due to less sunlight transmition.
 
Masonry opening
The space in a masonry wall left open for windows or door.
 
Mortise
A slot or rectangular cavity cut into a piece of wood to receive another part.
 
Mortise-and-tenon
A strong wood joint made by fitting together a mortise in one board and a matching projecting member (tenon) in the other. Used as a corner joint in Pella sashes.
 
Mullion
A wood or metal part used to structurally join two window or door units.
 
Muntin
Applies to any short or light bar, either vertical or horizontal, used to separate glass in a sash into multiple lights. Also called a windowpane divider or a grille.
 
Muntin Bar
Any small bar that divides a windows glass. Also called a grille or windowpane divider.
 

Oriel style window
A double hung window configuration that consists of a lower sash that comprises 60% of the window height.
Palladian window
A large, arch-top window flanked by smaller windows on each side.
 
Panel
Usually refers to the separate panel or panels in a door frame.
 
Parting stop
In a double-hung window, a strip of wood applied to the jamb to separate the sash.
 
Pleated shade
A shade of folded fabric which can be installed like regular shades or between the panes of glass of a Pella Designer Series® window.
 
Rail
The top and bottom horizontal members of the framework of a window sash.
 
Replacement window/New window
A replacement window is one that disturbs the interior trim and exterior siding very little because the unit is installed in the frame of the old window.  Only the sashes and window tracks are removed but not the frame.  A new window is one that is inserted into the framed opening as did the original window.  This application often requires extensive siding and trim work/replacement.
 
Rough opening
The framed opening in a wall into which a window or door unit is to be installed.
 
R-Value
Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value.
 
Pane
A framed sheet of glass within a window.
 
Sash
A single assembly of stiles and rails made into a frame for holding glass.
 
Sash cord
In double-hung windows, the rope or chain which attaches the sash to the counter balance.
 
Sash lift
A protruding handle screwed to the inside bottom rail of the lower sash on a double-hung window. Available on all Pella double-hung windows.
 
Sash weights
In older double-hung windows, the concealed cast-iron weights which are used to counterbalance the sash.
 
Sidelights
Narrow fixed units mulled or joined to door units to give a more open appearance.
 
Sill
The main horizontal member forming the bottom of the frame of a window or door.
 
Single glazing
Use of single panes of glass in a window. Not as energy-efficient as double glazing.
 
Single-hung
A double-hung type of window in which the top sash is fixed or inoperable.
 
Slimshade® blinds
On Pella Designer Series® windows, a narrow-slat venetian blind positioned between the exterior glass and the interior double glazing panel.
 
Stile
The main vertical members of the framework of a sash.
 
Stool
An interior trim piece on a window which extends the sill and acts as a narrow shelf.
 
Stop
A molding used to hold, position or separate window parts.
 
Tempered glass
Glass manufactured to withstand greater than normal forces on its surface. When it breaks, it shatters into small pieces to reduce hazard.
 
Tenon
A rectangular projection cut out of a piece of wood for insertion into a mortise.
 
Thermal break
The addition of a thermal insulating material between two thermally conductive materials.
 
Thermopane glass
A glass configuration comprised of two or three panes of glass with a sealed air space between the panes of glass slowing the transmission of temperature between the living space and the exterior of the home.
 
Tilting sash

A popular modern window feature that allows the sash to be tilted in for easy access for cleaning purposes.
 
Transom
A small window that fits over the top of a door or window, primarily for additional light and aesthetic value.
 
U-value
Rate of heat flow-value through the complete heat barrier, from room air to outside air. The lower the U-value, the better the insulating value.
 
Unison lock
A casement locking system which secures the window at two locking points by operation of one handle. Standard on all but the shortest Pella casement windows.
 
Vent Unit
A window or door unit that opens or operates.
 
Vinyl
A plastic material used by many window manufacturers (not Pella) for cladding or entire window units.
 
Weatherstripping
A material or device used to seal the openings, gaps or cracks of venting window and door units to prevent water and air infiltration.
 
Windload
Force exerted on a surface by moving air.

Home | About Us | Products & Services | References | Faq's & Technical Help | Portfolio | Coupons | Contact
©2010 Jarvis Exteriors, Inc. All rights reserved. Designed by FDI Creative Services, Inc. | Houston Web Design