What’s the difference between a bay and a bow window? Should I care about the U-factor? And what’s a “muntin”, anyway?
Your local Infinity from Marvin partner is a window and door expert, so you don’t have to be. Your free, no-hassle consultation will provide all the information you need to make the best decision, and in a way that makes sense for you.
However, windows are an investment in your home so more information is better. Our glossary of terms is a great place to start!
Casement Window - A casement window is side-hinged window that swings out from the left or right with crank-out hardware.
Condensation - Moisture that forms on a surface. This could be a result of a difference in temperature between the surface and the air, or high humidity in the home.
Daylight Opening (DLO) - The area of the window or door where light passes through; the width and the height of the visible glass.
Double Hung Window - Infinity double hung windows have two movable sash (top and bottom) which are hung in the window frame and slide/operate vertically.
Frame - The stationary portion of a window that surrounds either the glass (direct glaze) or the sash (operating or stationary). There are three components to the frame: the header across the top, the jambs down each side, and the sill across the bottom.
Hardware - WIndow hardware includes locks, crank handles, and hinges on windows used to operate and secure them.
Low E Glass - Extremely thin coating of special low emissivity (low E) metallic material are applied to glass pane to boost energy efficiency and block out UV rays.
R-Value - The resistance a material has to heat flow is the R-Value. Higher numbers indicate greater insulating capabilities.
Sash - The operating and/or stationary portion of the window that holds the glass and is separate from the frame.
Sill - The lower, horizontal piece of a window or exterior door frame that supports the frame.
Single Hung Window - A single hung window looks like a double hung, but only the bottom sash moves up and down.
U-Factor - U-factor measures how well a window keeps heat inside your home. A higher number allows more heat to escape; a lower number allows less heat to escape. If you live in a colder climate, you’ll want to look for a low U-factor.
Ultrex® - Ultrex Fiberglass is a proprietary fiberglass composite material made of resin and glass fibers with an integrated finish for durability. This superior material is used in Infinity products.
Argon Gas - Argon gas is a colorless and odorless gas that is less dense than air. It is used to fill the air space between glass panes to increase energy efficiency.
Assembly - Two or more window units mulled (attached) together to create one larger grouping.
Bay Windows - A series of windows installed in an angled “bay” formation with a head and seat board. Typically, a bay window consists of two smaller operating units flanking a larger fixed center window.
Bow Windows - Bow windows are a series of adjoining window units that are configured in a gradual arc.
Check Rail - The horizontal portion of a double hung window where the top and bottom sash meet. Simulated check rails use bars to simulate the look of a double hung window in a casement or glider.
Cottage Window - A cottage window contains an unequal sash, top and bottom. Bottom sash is larger than top sash.
Divided Lites - Decorative bars permanently adhered to glass (Simulated Divided Lites) or between two panes of glass (Grilles Between Glass) to add architectural interest on a window or door.
Full-Frame Replacement - Existing windows are completely removed down to the studs and the new window is installed in the opening.
Insert Replacement - New windows are installed within the existing frame. Only the old sash, hardware, and covers are removed and replaced.
Mull/Mulling - Mull: the actual components used to attach two or more windows and/or door units together to form an assembly.
Mulling: the process of attaching two or more window or door units together.
Muntins - Bars that form the decorative grille pattern on a window or door.
Operator - A moving sash, panel, or unit.
Oriel Window - An oriel window has an unequal sash, top and bottom. Bottom sash is smaller than the top sash.
Panel - Stationary or operating portion of the door that holds the glass and is separate from the frame.
Picture Window - A fixed/stationary window to align with the profiles of operating windows. Sash is non-operable and attached directly to the frame. Often available in significantly larger sizes than accompanying operating windows.
Polygon - Polygon windows are direct glazed in various shapes such as triangles, rectangles trapezoids, pentagons, hexagons, and octagons.
Round Top - An arched window that is directly glazed to the frame. Add visual interest to a room and natural light.
Sash Lock - A locking device that holds a window shut, such as a lock at the check rails of a double hung unit. Larger units utilize two locks.
Single Hung Round Top - Infinity single hung round top windows provide a is an arched top built on a single hung window frame.
Weather-Stripping - A strip of resilient material designed to seal the window or door in order to reduce air and water infiltration.
XO - The letters OX or XO identify the operation of window or door units as viewed from the exterior. The letter O stands for stationary, while the letter X stands for operating.
We hope the glossary of window terms is helpful for you. For more, check out our complete glossary. Also be sure to check out our other blog articles, as we compare window materials and share information on how to pick the best windows for your home.
Questions regarding your windows? Schedule a free consultation with a local expert who can answer any questions you may have about windows and window replacement.
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