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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!

The Basics: Windows 101
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.
Go Deeper: Impress your friends!
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.
Questions regarding your windows? Schedule a free consultation with a Charles representative who can answer any questions you may have about windows and window replacement.