Glass Basics - Glass Types and Thickness

Annealed Glass

Annealed glass is the most common glass that is used for multiple purposes. Annealed glass is used as standard window glass, picture frame glass, table tops, mirrors and in many other places.

Annealing glass is done to by heating the glass to a certain transition temperature which makes the glass tougher to break (keep in mind that annealed glass is still fragile of course). Annealed glass breaks in long “runs” which can produce large, pointed and very very sharp edges when broken or cut. Handle all broken glass and cut glass edges with care, as these fresh edges are razor sharp.

Most glass used in replacing single pane window glass, picture frame glass, patio table tops and mirror are typically all annealed glass.

 

 

Tempered Glass

Tempered glass has been heat-treated, toughened, hardened or tempered as it may be called and may not be cut or altered in shape. Tempered glass is more difficult to break and is commonly used for large windows, doors, glass furniture, shower englosures and for many other uses. Tempered glass is a safety glass, which when broken poses no immediate threat of cutting a person. When tempered glass breaks, it falls into small cubic pieces that are not nearly as sharp as broken annealed glass. This is the type of glass you will see on the ground at the scene of an automobile accident. Tempered glass is used in doors, areas surrounding doors, oversize glass, glass shelving, and automotive side window glass and in numerous other applications.

 

Laminated Glass

This is produced by bonding two or more pieces of annealed glass to a strong continuous membrane. Since its parts are annealed, most laminated glass may be cut with a typical glass cutter by scoring both sides in precisely the same location on both sides. The inner membrane must be cut after the scored glass has been run with a sharp instrument, sometimes requiring heating of the seam to make the membrane soft and flexible therefore accessible. Laminated glass is commonly used in place of tempered glass when a repair is needed immediately. It is also used as a safety glass in upper floor commercial windows and in other commercial storefront applications. Most people are more familiar with laminated glass in the form of an automotive windshield.

 

Common Glass Thickness

3/32” SS or Single Strength 1/8” DS or Double Strength 3/16” Plate

1/4" Plate 3/8” Plate 1/2" Plate

Insulated Glass also referred to as IG, Insulated Unit or Thermopane

An insulating glass unit is manufactured utilizing two or more layers of glass separated by an insulating airspace. Most insulated glass units are created using a spacer placed between the panes of glass, and is sealed with a material that bonds the components together and provides an airtight seal. Many of these units contain a desiccant to absorb moisture within the unit, and may contain internal muntins for appearance. The addition of certain coatings and gasses to the interior of the unit are used to increase its insulating properties and energy deflection or retention properties.

The direct transfer of heat or cold from the outside surface of the glazing to the inside of the glazing is highly reduced when using insulated glass as opposed to a single glass. The U-value (the calculation of heat transmissoin or thermal conductance) is effectively doubled when employing the insulated glass unit over a single pane of glass. The interior side of an IG unit remains a more similar, relative temerature to the interior of a building than does single pane glass, and if in working condition, will not accumulate moisture or frost nearly as much if at all as compared to a single pane window.