Installing windows in your home is not always as straightforward as you might think. The location of the windows is critical when choosing the glass used. Some windows, based on their height from the floor or ground, must be made of tempered glass. If you adjust the height of the installation, you may be able to opt out of using this specialty glass and install regular window glass instead.
Tempered Glass Versus Nontempered
The tempered glass required in dangerous locations is different from the glass usually used in windows. The tempering process exposes the glass to high temperatures, which strengthens it to four or five times that of regular glass. Hitting a pane of tempered glass is less likely to break it, and if it does break, the glass does not shatter into sharp pieces. Tempered glass breaks into small chunks without sharp sides.
Location of Tempered Glass
Where to install windows with tempered glass is not just dictated by the height of the window. According to "Code Check Complete: An Illustrated Guide to the Building, Mechanical, and Electrical Codes" by Redwood Kardon, et al., conditions requiring a window to have tempered glass include a window lower than 18 inches from the ground, larger than 9 square feet in area, with a top higher than 3 feet above the ground and an interior or exterior path within three feet of the window. All of these criteria must be met for tempered glass to be required. Generally, you can use nontempered glass if your window does not fit all four requirements, but there are exceptions.
Doors and Windows
Nearby doors change the rules about tempered glass because the swing of a door or the motions of a person going through it can create a situation where a regular window might break. Any windows in a door must have tempered glass, no matter the height, unless it is too small for a 3-inch ball to pass through the window. If you are installing windows within 2 feet of a door and lower than 5 feet from the ground, you need tempered glass in the windows, even though these might be higher than 18 inches from the ground.
Skylights bring natural light from the roof into your home. Though these are installed on the roof, nowhere near doors and much higher than 18 inches from the ground, you cannot use regular, nontempered glass in a skylight. Tempered glass is required to prevent a broken skylight from raining shards of glass down on people or pets below. The extra strength of tempered glass also ensures that a tree branch falling on the skylight or an animal running across your roof will not break the glass.