Beading
This architectural term refers to a narrow, half-round molding that spans the edge of the vinyl siding.

Beveled Exterior
An angled extension from the frame that adds an aesthetically-pleasing dimension to the exterior of the window.

Block Frame Window
Used when replacing the wood sash of an old double hung wood window.

Bow Window
A composite of four or more window units in a radial or bow formation.

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.

Caulk
A mastic compound for filling joints and sealing cracks to prevent leakage of water and air, commonly made of silicone, bituminous, acrylic, or rubber-based material.

Caulking
To fill a joint with mastic or asphalt cement to prevent leaks.

Clapboard
A thin, narrow board with one edge thicker than the other, used as vinyl siding. CertainTeed siding brands offer clapboard-style siding in different exposures, several different textures, and even different panel projections.

Conduction
Energy transfer from one material to another by direct contact.

Convection
Heat transfer by currents that flow from a warm surface to a colder one.

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.

Drip Edge
A non-corrosive, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction.

Double or Dual Glazing
Use of two panes of glass in a window to increase energy efficiency and provide other performance benefits.

Dutchlap
A beveled-edge panel that was popularized by early American settlers.

Emissivity
The relative ability of a surface to radiate heat.

Exposure
The width of each "board" of siding. Also called a reveal.

Extrusion
A form produced by forcing material through a die. Most window frames are clad with extruded vinyl or aluminum.

Fascia
Architecturally, "fascia" refers to a flat, horizontal band. A flat board that runs horizontally along the eaves of a roof, typically capping the ends of the roof rafters to give the roof edge a more finished look and provide a base for attaching gutters.

Fenestration
An architectural term referring to the arrangement of windows in a wall. From the Latin word, "fenestra," meaning window.

Fiberglass
A composite material made by embedding glass fibers in a polymer matrix. May be used as a diffusing material in sheet form, or as a standard sash and frame element.

Finish
Refers to the texture (and sometimes the gloss level) of a siding panel. For fiber cement, this refers to the coating used to finish the siding. Usually an opaque paint; solid or semi-transparent stain.

Fixed Window
Non-venting or non-operable window. Also known as picture window.

Flashing
A thin strip of metal or synthetic material that diverts water away from a window or skylight.

Frame
The enclosure in which window sash or door panels are mounted.

Frieze
The horizontal member connecting the top of the siding with the soffit.

Glazing
Glass in a window or door; the act or process of fitting with glass.

Glazing Bead
A plastic or wood strip applied to the window sash around the perimeter of the glass.

Glazing Stop
The part of the sash or door panel which holds the glass in place.

Gutter
The trough that channels water from the eaves to the downspouts.

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.

Insulation Performance Glass, I-P Glass
The most energy efficient, money saving glass available today. No haze - inferior Low-E's have "oil can" effect. Reduces condensation - highest winter interior glass temperature. Prevents fading, filters out 84% of harmful UV. Saves on energy.

Insulating Glass
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.

Jamb
The main vertical members forming the sides of a window or door frame.

Lineal
Molding of various widths used to trim storm door and window openings at the jambs. Also referred to as:box post, window and door surround.

Light or Lite
Glazing framed by muntins and/or sash in a window or door.

Lintel
A horizontal member above a window or door opening that supports the structure above.

Low-E Glass
A common term used to refer to glass which has low emissivity due to a film or metallic coating on the glass or suspended between the two lights of glass to restrict the passage of radiant heat.

Masonry Opening
The space in a masonry wall left open for windows or door.

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.

Nail Hem
The top edge of a siding panel, where it is nailed to a wall.

Overhang
That portion of the roof structure that extends beyond the exterior walls of a building.

Overlap
Area where two pieces of lap siding are overlapped. This dimension is usually 1 1/4".

Panel Projection
The section of siding that projects from the wall. As a rule of thumb, a larger panel projection creates a more pronounced shadow line.

Picture Window
Non-venting or non-operable window. Also know as a fixed window.

Profile
Side view of a siding or soffit panel.

Rail
The top and bottom horizontal members of the framework of a window sash.

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 Lift
A protruding handle screwed to the inside bottom rail of the lower sash on a double-hung window.

Seat Board
A flat board cut to fit the contour of a bow or bay window and installed between the sills and the flat wall surface, providing a seat or shelf space.

Shadow Line
The shadow pattern cast by a particular siding in the sunlight. Shadow line is influenced by the style and panel projection of the siding.

Shims
Wood wedges (often wood shingles) used to secure the window or door unit in the rough or masonry opening in a square, level and plumb position during and after installation.

Sidelites
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.

Simulated Divided Lite
A method of constructing windows in which muntins are affixed to the inside and outside of a panel of insulating glass to simulate the look of true divided light.

Single Glazing
Use of single panes of glass in a window. Not as energy-efficient as double glazing.

Single-hung Window
A double-hung type of window in which the top sash is fixed or inoperable.

Slider Window
Both sashes slide horizontally in a double-sliding window. Only one sash slides in a single-slider window. Ventilation area can vary from a small crack to an opening of one-half the total glass area. Screens can be placed on the exterior or interior of the window unit.

Slope
The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in feet.

Soffit
Usually the underside of an overhang or eaves.

Stile
The main vertical members of the framework of a sash.

Strikeplate
Protects the jamb from the hardware latch on a door. Covers the latch and deadbolt.

Square
Unit of measure for siding equal to 100 square feet (or a 10-foot by 10-foot wall section).

Tempered Glass
Glass manufactured to withstand greater than normal forces on its surface. When it breaks, it shatters into small pieces to reduce hazard. Standard on all doors and large fixed windows.

Thermal Break
The addition of a thermal insulating material between two thermally conductive materials.

Threshold
The bottom part of the door frame, i.e. the area you step on when entering or exiting through the doorway.

Transom
A small window that fits over the top of a door or window, primarily for additional light and aesthetic value.

True Divided Lite
A term which refers to windows in which multiple individual panes of glass or lites are assembled in the sash using muntins.

uiPVC PE
Unplasticized - so it won't bend or flex. Impact-Resistant - so it won't crack or break. PolyEthelene shield protects colors from fading in the sun.

Vent Unit
A window or door unit that opens or operates.

Vertical Siding
Also referred to as "panel siding", this rectangular shaped siding is typically manufactured in 4 x 8, 4 x 9 or 4 x 10 sizes. Vertical siding is never overlapped. Solid vinyl soffit can also be used as vertical siding.

Vinyl
A plastic material used 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.

X-Treme Tough Glass XTG
Glass Breaks into harmless pieces like a windshield and is 400% stronger than ordinary glass! XTG is mandatory in skylights, doors, windows less than 18" from the floor and any window over a bath tub or shower. XTG helps protect your family from intruders.