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Understanding “Window Speak” - a Buyer’s Guide

By Gates Dearen

When it comes to shopping for replacement windows these days, it almost seems as complicated as shopping for a new car.  Just as with the auto industry, modern windows come in many makes and models, and they offer a number of optional extras.  Everything from the hi-tech materials used in frames and panes, to attachment and pivot points - all have a nomenclature of their own.  If you don’t know a “head jamb” from a “Muntin Bar”, let me help explain.

Just as a motor vehicle has several key components, so too do modern replacement windows.  Where a car has a chassis, a window has a Frame.  Where a car has doors, windows have Jambs which allow them to slide up and down, or pivot in or out.  Both cars and windows have trim that is used to fit exterior components together seamlessly.  Both cars and windows also have cams.   The kind used on windows are mechanisms that pull the sash together when placed in the locked position. (A Sash is the part of the window containing the glass.)  

In an automobile, a header refers to aftermarket exhaust manifolds designed to enhance performance.  In a window, the Head is the top part of the window frame that spans the width of the frame.

Where a roll bar on a convertible creates a safety structure that protects driver and passenger in the event the car rolls over, a Muntin Bar on a window is used to create a boundary between individual window panes.  On the other hand, a Mullion is a vertical or horizontal connecting unit between two windows.

While windows don’t have fuel injection, they do have air chambers within the sash and frame that help to add insulation and strength. Both cars and windows employ independent suspensions.  Replacement windows employ a Balance System, which suspends a counterbalance in order to allow the vertically sliding sash to open and close, as well as remaining in a desired fixed position. 

Sashes and motor vehicles, both need to have proper alignment in order to drive straight.  A Sash Alignment System attaches the sash to the balance. This both creates proper alignment between the sash and the frame, while permitting the sash to tilt for cleaning.

While the auto industry used to talk about four on the floor, we in the replacement window industry talk about Double-Hung windows, which is a window with two sashes that can slide vertically.     

Weather stripping is used on windows and cars for much the same purpose: to form a weather-resistant seal.


While replacement windows don’t have burglar alarms, they do have several built-in security systems.  Vent locks are latching mechanisms on the inside of the window that allow you to leave the window partially open for ventilation purposes. A Tilt Latch unlocks the sash and allows it to tilt in from the main frame. A cam lock is a mechanism that pulls the sash together when locked.

Where the Rubber Meets the Road

Where the automotive industry talks about horsepower and fuel efficiency, we in the window business talk about R-Value and Low-E Glass. While replacement windows won’t go from 0-60, they are most definitely built with fuel efficiency in mind.  A great deal of time and money has gone into designing windows to keep the worst that mother nature has to throw at you, out of your home.  R-Value denotes the resistance a given material has to heat flow.  The higher the R-Value, the greater the resistance. Low emissivity glass, otherwise known as Low-E Glass, is glass that has been coated with a transparent metal oxide coating designed to reflect infrared energy.

Unlike R-Value, in which a high value is preferred, there is U-Value which denotes the amount of heat transferred through a material.  The lower the U-Value, the better the insulating power.  UV Block indicates how much of the Sun’s rays are kept from penetrating through the glass.  The lower the number, the less ultraviolet gets through the window.

Conduction denotes energy transfer from one material to another through direct contact.
Convection refers to heat transfer from a warm surface to a cold one.

Just as a car uses either unleaded gas or diesel, there are several kinds of gas used in the replacement window business.  The first is Argon Gas, which is a colorless, odorless gas that is six times more dense than air.  It is injected between the window panes to reduce heat transfer.  Krypton Gas sounds like something that would deter Superman.  What it actually does is reduce heat loss, since it’s 12 times denser than air.

Just as cars in the 50’s had fins, so to some replacement windows.  A Flush Fin window is used when replacing an existing aluminum sliding window. A Block Frame window is used when replacing the wood sash of an old double hung wood window. 

If you hear a window professional talk about a Sloped Sill Adapter, he or she is referring to a device that is used to cover the gap between an old sloped sill window, and a new block frame window.  The adapter helps to fit the new window to the existing sloping sill.

Wet and Dry Glazing refers to the method used to secure the pane to the sash.  Wet glazing uses a silicone sealer, while dry glazing refers to the way in which reflective coatings are adhered to a window.

Makes and Models

Just like cars, replacement windows come in a variety of makes and models.

  • An Awning Window has a hinge atop it that permits it to swing up for ventilation.
  • A Bay Window is an angled combination of three windows that project outward from the wall of a home.
  • A Bow Window is a series of windows attached at 10-degree angles that bow into a semicircular appearance.
  • A Casement Window is a side-hinged sash that opens outward for ventilation.
  • A Picture Window is a window that has no movable sash.
  • A Hopper is a window with a bottom hinged sash that is designed to open inward.
  • As its name suggests, a Slider Window is a window where the sash slides horizontally.


I hope that this list of commonly used terms helps with your understanding and appreciation of replacement windows.  Look at the bright side, while new windows can make your home more attractive and energy-efficient, at least you’ll never have to worry about your teenage son or daughter asking you if they can take them out for a drive.

HomeRite is a window and door dealer that specializes in energy efficient, quality windows with warranties and service to match. The company has been in business since 2005 HomeRite has partnered with a manufacturer that has been producing high-quality products and providing excellent customer service for over 60 years. Windows and doors from HomeRite are some of the highest quality, most thermally efficient windows and doors on the market.

HomeRite products add substantial value to their clients’ properties. HomeRite is a member of the United States Green Building Council, a non-profit organization comprised of leaders across the industry working to advance environmentally responsible buildings.


Gates Dearen is the co-owner of HomeRite Windows and Doors in Jacksonville, Florida. He and Richard Walden have been serving the building products industry in Florida for over 25 years. They strive to match homeowners with the right windows and doors for their homes and budgets. They make the home improvement process pleasant with first-rate, energy-efficient products, affordable pricing, and award-winning installers who employ the best practices and who always treat customers and their property with the utmost respect.

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3 comments:

  1. Wow! Who knew there was a secret language that only window professionals can speak. Thanks for the secret decoder ring.

    ReplyDelete
  2. Like all industries, they have their own lingo. I found it useful to brush-up before talking to any industry rep first, that way I understood what they were saying the first time.

    ReplyDelete
  3. Good read, It really is incredibly fantastic and informative website. Good to discover your site Very well article! keep sharing.
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    ReplyDelete