Find useful information regarding the of options available when choosing windows for your project.




Building Codes


Welcome to the Progressive Windows Glossary of Terms. This will help to familiarize you with the terminology used both on this site and when you when discussing windows with us.

Argon Gas
A colorless and odorless gas used to fill the airspace between two pieces of glass in a dual glazed unit. The addition of argon greatly increases the performance of Low-E Glass.

A moulding applied to the stile of a French Door, Sliding French Door or French Casement window unit which the other door panel or window sash strikes. Usually head and footbolt devices will be found on the astragal side.

Single units mulled together

Brick Mould Casing (BMC)
An exterior moulding of window and door frames that abuts the exterior facing material of the structure. The casing serves as the boundary moulding for brick or other siding material and also helps to form a rabbet for screens and/or storm sash or a combination door.

Check Rails
Horizontal sash members that meet, as in double hung units. These could also be vertical check stiles, as in a horizontal slider or patio door.

Refers to wood windows and doors which are covered with an extruded permanent colored aluminum jacket on the exterior frame and sash.

Cottage Window
A window with an unequal sash, top and bottom.

Daylight Opening
The width and height of the visible glass.

Direct Set
Refers to a window with no sash. The glass is glazed directly into the frame and is stationary.

The way by which a person exits. Refers to building codes that require windows to be a certain size in any room a person could use for a sleeping area.

A measure of a surface's ability to emit long-wave infrared radiation or room temperature radiant heat energy . Emissivity varies from 0 (no emitted infrared) to 1 (100% emitted infrared). The lower the emissivity, the lower the resultant U-Value

A term used to describe a side or lateral part. Also used to describe a 3-wide picture unit or bay in which single-hungs, double-hungs or casements are attached on either side.

French Casement
Casement window with two sashes in one frame that opens without being restricted by a vertical mullion when the both sashes are open.

Glass Size
The measurement of the actual glass, not the visible glass

Installing Glass into a window

Removable wood divider made to simulate true divided lites.

Term used to describe the right or left hand operation of a window or door.

Insulating glass
Another term for Dual Glazed

Jamb Extension
A jamb like member, usually surfaced on four sides, which increases or extends the depth of the exterior or interior window or door frame.

Laminated Glass
Glass composed of two sheets of glass fused together with a sheet of transparent plastic between the sheets.

Low-E Glass
Low-E stands for low emissivity. Low-E glass coated with a thin, virtually invisible, metal or metallic oxide layer. The idea is to reduce the amount of ultraviolet and solar heat gain allowed to come into or escape from your home.

Masonry opening
A brick, stone or block opening into which a window or door unit is installed including the outside casing.

The act of attaching two or more window or door units together.

The vertical member of a sash, window or door frame between openings in a multiple opening frame.

Muntins, or 'Munt'
Horizontal or vertical 'bars,' extending from a bar to a stile or rail or another bar. Used in reference to divided lites or grilles.

Nailing Fin
A factory installed vinyl strip that is inserted into a kerf in the frame of clad units. Nailing fin installation is the standard method for installing windows.

Obscure glass
Glass formed by running molten glass through special rollers. This gives the glass a texture making it translucent.

OX and XO
The letters OX and XO identify the operation of a window or door units as viewed from the exterior. The letter O stands for stationary while the letter X stands for operating

A groove along or near the edge or a piece of wood.

The cross or horizontal members of the framework of a sash, door or other panel assembly

Also called retro-fit, refers to units which are sized for replacement over an existing window frame.

Term used to describe the steel drive worm, gears and crank device used for opening awnings and casements.

Rough Opening
The opening in the wall where a window or door unit is to be installed. Openings are larger than the size of the unit to allow room for insulation and to shim the unit square.

The operating and/or stationary portion of the window unit that is separate from the frame. The sash consists of the following parts:

Sash Lock
A locking device which holds a window shut, such as a lock at the check rails of a double hung unit.

A wedge or strip of wood used to level and square a window or door in the rough opening

A stationary glass panel mulled to or installed next to a door.

The horizontal member forming the bottom of a window or exterior door frame, the lowest member of the frame of a structure resting on the foundation and supporting the frame

Spacer or Spacer Bar
Used to separate the two pieces of glass in a Dual Glazed unit. This may be just around the edges of the glass, in a pattern if Modern Divided Lites are used.

A semi-elliptical area, the lower center is the point where the divided lites meet and extend outward in spokes.

The upright or vertical perimeter pieces of a sash, door or screen.

Similar to the starburst, this pattern also contains one elliptical bar that divides the window into 2 arches through which the remaining bars spoke.

Tempered Glass
Tempered glass is a both stronger and safer than regular glass, as it is tougher to break. If it is broken, it breaks into little beads rather than shards. Tempered glass may be required in certain areas (i.e. within 24' of a door)

A window a above a window or a door. Transoms can be either stationary or operating

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When choosing windows, glass is probably the one of the last things you think of. Yet it's one of the most important things to consider in the way of both appearance and energy efficiency. Adding privacy or beauty to a room is just the beginning.

Dual Glazed versus Single Glazed
For the most part, dual glazing has become the industry standard. For a small price increase (if one at all) they have been proven to decrease the effect the temperature outside has on the inside of your house. If you live in the city, dual glazed windows will be a dream come true especially if you live near an airport or freeway. While single glazed windows may be a good choice when attempting to match existing ones, for performance, dual glazing is the best.

Low-E Glass
The best thing you can do for your home and everything inside of it is get Low-E Glass. Low-E(emissivity) is a transparent thin coating on one side of the glass that is composed of layers of silver sandwiched between layers of metal oxide coatings. The result is significant reduction in "short-wave radiation" and ultraviolet rays that damage carpet and furniture; far superior to tinting in performance, it still allows most natural light in while reducing the most damaging part of it. It also assists in lowering heating and cooling bills. In the summer, "long-wave radiation" is reflected back outside, lowering cooling costs. In the winter, internal long-wave radiation is reflected back into your home, lowering heating cost.

Divided Lites
A favorite way of adding beauty and depth to a room is with divided lites, (grids). You have several options. If true divided lites are a consideration, you may want to look at "Simulated Divided Lites" (SDL). Rather than breaking up the Glass, SDL applies an interior and exterior grid of the same pattern, then to complete the effect, may put a spacer bar in between the panes of glass. This lowers cost, in addition to increasing the perfomance of the window.
If the difficulty associated with cleaning windows with divided lites is a concern, you may want to consider grills between glass or airspace grilles. This simply puts one set of grills between the two panes of glass, keeping them away from the elements so they won't rust or get dirty. This also makes the window easier to clean as the entire surface of the glass is unobstructed.

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The first thing to consider when purchasing windows is the material you would like them to be made out of. It's important to pick windows that suit both your project and your life. Perhaps you want the slim lines of Aluminum or, if you're near the coast, vinyl or fiberglass might suit you better. Maybe you are trying to preserve or create a classic look in which only wood windows will do. If you are looking to replace your windows without the hassle of an extensive remodel, you may want to look into retro-fit windows, which are available in all frame types mentioned above.

Architects and builders have been specifying aluminum windows for years. Their overall strength and lasting value have made them a favorite on everything from custom home designs andlight commercial applications to entry level homes and large multifamily units. Also, their rigidity and durability allows them to be configured into large combinations without large mullions or structural members, allowing you to make the most of your views....and your imagination.

From the heat of the Arizona desert to frigid cold of Alaska, the weatherability, impact resistance and low maintenance of Vinyl is a top choice by builders and home-owners alike. In addition to never needing painting or excessive maintenance, choosing vinyl also gives you freedom of design allowing you to create a unique look. They won't warp or twist, meaning it will operate just as easily on an August afternoon as it will on New Year's Eve; all while maintaining comfort and energy efficiency of your home.

Imagine, if you will, the ultimate window. Would it be one that's stronger than aluminum with the energy efficiency of wood or vinyl? Would it have the same expansion and contraction properties of glass? Would it be a window made for any design, structural requirement or climate on the planet? Did you answer "yes" to any of these questions? If so, then fiberglass may be just what you are looking for. The same material used to keep boats above water is now being used to build windows due to the fact that it won't warp, peel, split, crack or pit. It gives the appearance of a painted wood window without the knotholes. and the energy efficiency and low maintenance of a vinyl window. And with the structural integrity of metal, you can design to your hearts content giving you the room you've always wanted.

Wood/Wood Clad
The first thing that comes to mind when looking at wood windows is the one in your dining room that hasn't opened since the Eisenhower Administration. Despite their beauty, you just don't want the hassle of maintaining wood windows. Well, good news. You no longer have to sacrifice beauty for low- maintenance. Clad wood windows have become the industry standard for some the finest custom homes in America. The term "clad wood" has come to mean several things, but a general definition is a window with a wood interior and an exterior of a less vulnerable material (i.e. aluminum or fiberglass). In some instances, the window will be all wood, with metal fixed to the outside. Other times the window will be made of vinyl or fiberglass with a wood veneer on the inside. Either way you get the warm feel and look of wood inside, without the painting and warping associated with conventional wood windows. Also, if you are matching or contrasting a specific color scheme, wood clad windows are untouchable. With the widest range exterior colors and hardware options, you are ensured to have a home that is uniquely you.

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building codes

We love selling windows...just not more than once. So we've constructed a list of tempering and egress codes to help make sure we get it right, the first time.

A window should be tempered if any of the following conditions exist:

  • The window glass is within 24" of either edge of a door in a closed position
  • The glass is within 60" of a tub or shower drain.
  • The glass is within 60" of the stair tread.
  • The glass is closer than 18" to the floor and more than 9 Square Feet
    ** Other conditions may require tempering

A window needs to meet the following conditions if the window is going to be in a bedroom, or any room that people may sleep in, such as a den or office. Remember, simply designating the room as something other than a bedroom may not exempt you from the egress laws

  • The window must be at least 20" wide
  • The window must be at least 24" high
  • If on the ground floor, the window must have a minimum clear opening of 5.0 Square Feet
  • If not on the ground floor, the window must have a minimum clear opening of 5.7 Square Feet
  • The sills must not be higher than 44" above the floor

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