On this page you will find a glossary of many home-improvement terms.

Click on a letter below to go to that section, or just scroll through the terms to find your definition.



Argon Gas

Argon is a safe, odorless, colorless, non-toxic, non-flammable inert gas that is commonly used in place of air between the glass panes of an insulated Low-E glass unit to reduce temperature transfer.


Bay Window

A composite of three windows, usually made up of a large center fixed unit and two flanking units at 30°,45° or 90° degree angles to the wall.

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.


Molding of various widths, thickness and shapes applied to the framework of window and door units.


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.


Energy transfer from one material to another by direct contact.


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.

Double or Dual Glazing

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



The relative ability of a surface to radiate heat.



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


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.

Fixed Window

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


Glazing Bead

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



A window unit in which the top of the sash swings inward.


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.


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.


Muntin Bar

Any small bar that divides a windows glass. Also called a grille or windowpane divider.



A framed sheet of glass within a window.



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


Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value.



A single assembly of stiles and rails made into a frame for holding glass.

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.


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-sliding 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.


The main vertical members of the framework of a sash.


An interior trim piece on a window which extends the sill and acts as a narrow shelf.

Stop Molding

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. Standard on all doors and large fixed windows.

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.



A measure of air-to-air heat transmission (loss or gain) due to thermal conductance and the difference in indoor and outdoor temperatures. As the U-Value decreases, so does the amount of heat that is transferred through the glazing material. The lower the U-Value, the more restrictive the fenestration product is to heat transfer.



A material or device used to seal the openings, gaps or cracks of venting window and door units to prevent water and air infiltration.

"Hiring your company to do a whole-house replacement of Paradigm windows was one of the best home-improvement decisions we've ever made! The original quote was competitive and fair, the work was completed on time, as promised, and the quality of the installation was excellent. Your personal attentions made it a real pleasure for us to be your customers! Thanks again for making our home so much nicer!"

-- John and Tamara Luchini

"I had new windows installed in the summer and am currently having a new door installed. The windows are very efficient and we have noticed a drop in our heating bills even with the extremely low temperatures this winter. The windows and trim look great and the whole experience from start to finish has been very professional. My kids still talk about Terry the installer. he is very thorough and does excellent work. I would recommend Advanced Window Systems to anyone I know."

-- Todd Schmitt

"We just wanted to let you know how pleased we are with our new windows! Terry, the installer, was professional, quick and so kind to our curious children who wanted to "help" him. We have noticed a difference in the warmth of our home this winter and a significant decrease in street noise. We are glad we chose Advanced Window Systems, INC and have already recommended you to our neighbors and friends."

-- Laura and Evan Miller

"Brett, Advanced Window Systems has hit another home run with us. We had your company remove old windows at our Elk Rapids cottage and replace with soft-lite windows two years ago. Your installer, Terry, did a great job of installing and trimming the inside and out. We have been impressed with the looks and functionality (lowered our heating bills by ~15%) of the Soft-Lite product.

As a result of our positive experience in Elk Rapids, we ventured with you again to change out 30+ windows in our 44 year old Midland home. Terry and Chris completed the job with perfection-same high degree quality of removal/installation/trim in and out as at the cottage. They were meticulous in workmanship and did a thorough job of keeping everything neat and clean as they progressed-both in indoors and out. And they did this in early December with short daylight days and cold temperatures. They were very professional and enjoyable to have around! Thanks for another great project!!"

-- H.J. "Gus" Garret