Strengthened Glass Windows

}}Infobox
|title = Strengthened Glass Windows
|image        = [[File:Space holder.jpg|215px|alt=Block Glass Windows]]
|header5 = Strengthened Glass Windows 
|data6   = Replacement Windows with Strengthened Glass
|header7 = Description:
|data8   = Windows in which the glazing is specially strengthened.{{

Strengthened glass windows offer a suitable replacement window solution for window applications in which the architectural design calls for splinter-proof glass panels. 

== Strengthened Glass Windows ==
Strengthened glass replacement windows include toughened or tempered glass panels which are specially treated to prevent splintering when broken. Architects, builders, contractors, interior designers and homeowners include strengthened glass replacement windows in home window designs in installations in which the sill height is low, if the window's span is especially large or if it is located near to a walking surface. Federal safety laws and local building codes provide guidelines regarding the legal requirements for safety glass in replacement window applications. 

=== Types of Strengthened Glass ===
There are five main types of strengthened glass -- annealed glass, fully tempered glass, heat strengthened glass, wired reinforced strengthened glass and laminated glass.
 
==== Annealed Glass ====
Annealed glass is a subset of toughened glass. The same thermal process of manufacture is used when creating annealed glass as is used when creating fully-tempered toughened glass, though annealed glass is only twice as strong as regular glass. Annealed glass is not generally code-approved for replacement window locations which require strengthened glass. 

==== Heat Strengthened Toughened Glass ====
Heat strengthened toughened glass is six to seven times as strong as float glass. Heat strengthened toughened glass is not as pressure-resistance as fully tempered glass. 

==== Fully Tempered Toughened Glass ====
Fully tempered toughened glass is four to six times as strong as annealed glass. It is often used in cooking applications. 

==== Wired Reinforced Strengthened Glass ====
Wired reinforced glass can be manufactured as clear plate glass or figure roll wired reinforced glass panes. They are unattractive due to the fact that the wire netting can be seen through the glass panes but may offer an economical option for [[egress emergency exit windows|emergency exit windows]] in which appearance is not a concern. 
==== Laminated Glass Strengthened Glass ====
Laminated glass is an especially durable type of strengthened glass in which two or more sheets of annealed glass are bonded together with a PVB plastic interlayer. These windows ensure that, if broken, the PVB interlayer will hold the glass together and prevent shattering. This type of strengthened glass is especially useful in thwarting intruders. In addition, laminated glass provides greater sound insulation properties and blocks 99% of transmitted Ultraviolet light. Laminated glass panes are available in various tints and can be installed in window frames and sashes of all sizes.  

=== Manufacture ===
Safety glass is manufactured using controlled chemical or thermal treatments which increase its strength. The process of tempering involves heating float glass in uneven spurts to create internal layers within the glass panel. The layers enhance the strength of the glass and create sturdy glass panels that shatter, when broken, rather than splintering into sharp chunks or shards.

=== Advantages of Strengthened Glass ===
Safety glass is a safer glass alternative than float glass, especially in areas in which small children move around or there are higher-than-normal chances for an accident to occur.  

=== Disadvantages of Strengthened Glass ===
While strengthened glass windows can add an element of safety to a room and is even required by law in specific window applications, there are also disadvantages to strengthened glass windows. 

==== Manufacture ====
The size and shape of a window which is produced with strengthened glass must be fixed before the window is tempered. Cutting and grinding will cause strengthened glass to fracture. After a glass frame is cut to the desired size and shape, it undergoes the tempering process and cannot be changed. 

==== Cost ====
Strengthened glass is a more costly glass alternative than float glass. Many home designs create a window that combines both a strengthened glass pane and a float glass pane. This reduces the window's cost but still meets safety standards. In [[double pane windows|double-pane]] or [[triple pane windows|triple-pane]] windows, one pane may be a strengthened glass pane while the second pane is float glass. In a [[single hung windows|single-hung]] or [[double hung windows|double-hung]] window, the bottom sash may be manufactured using strengthened glass while the top pane is built with float glass.   

==== Scratches ====
The surface of strengthened glass is soft and can easily be scratched. 

==== Security ====
In case of a break-in, the strengthened glass window may completely disintegrate, allowing an intruder to enter the house. 

=== Home Applications ===
Conditions which require a window to have strengthened glass include applications in which the window is lower than eighteen inches from the ground, includes a top that's higher than three feet from the ground, has an interior or exterior path within three feet of the window or is larger than nine square feet in area. In addition, if the windows are installed within two feet of a door, they must have strengthened glass due to the possibilities that a swinging door could crash into the window.