A Look at the Various Types of Window Glass

Posted: Apr 02, 2012
Author: G&S Contracting, Inc.

Like all components of a home, a window is the sum of many parts – however, window glass is the most important element. After all, this is the piece of hardware that allows natural light to find its way into our homes, while enabling us to see the world outside. Window glass is available in several forms, but for architectural purposes, it is either tempered or annealed.

Tempered Glass

• Tempered glass is also called safety glass. During the manufacturing process, the glass is heat-strengthened, so that, if shattered, it will break into tiny squares. Tempered glass is therefore commonly used for bathroom windows, glass doors and other large windows. The panels have a much higher degree of thermal resistance than standard glass.

Annealed Glass (Standard)

• This is not treated for additional strength. When it breaks, it shatters into shards. Although annealed glass is still found in many windows, most building codes prohibit its use for low-level windows, bathrooms, fire escapes and door panels.

Glazing and Coating

• Other types of window glass are obscured or frosted (for privacy), glass blocks, reflective, and tinted. Window glass is often coated or glazed. Glazing refers to 2 pieces of glass being hermetically sealed together, with an air space in between to provide thermal qualities. Double or triple glazed window glass with low emissivity has pretty much set the bar for energy-efficiency.

In other applications, a reflective coating can be applied. In thermal terms, this is similar to glazing because the window appears transparent from the inside but it reflects UV radiation on the outside – minimizing an accumulation of solar heat.