No, a 71 x 60 window does not automatically need tempering based on size alone, but it likely does due to its location and other code factors. In most U.S. building codes, tempered glass is required for windows in specific hazardous locations—such as near doors, stairs, or in bathrooms—and for windows with certain dimensions relative to the floor. A 71-inch by 60-inch window is large enough that it may fall under the “large pane” rule, which often mandates tempering if the glass is within 18 inches of the floor and the window is over 9 square feet. Let’s break down exactly when and why this matters.
What Does Tempered Glass Mean?
Tempered glass is a type of safety glass that is heat-treated to increase its strength compared to standard annealed glass. During manufacturing, the glass is heated to about 1,200°F (650°C) and then rapidly cooled, which puts the outer surfaces into compression and the interior into tension. This process makes the glass roughly four to five times stronger than regular glass of the same thickness. When it does break, it shatters into small, rounded pebbles rather than sharp shards, significantly reducing the risk of serious injury.
Building codes require tempered glass in locations where the risk of human impact is high—such as doors, sidelights, shower enclosures, and windows near floors or bathtubs. The intent is to prevent severe lacerations if someone falls into the glass.
Why Size and Location Matter
The International Residential Code (IRC) and International Building Code (IBC) define “hazardous locations” for glazing. For windows, the key criteria are:
- Distance from floor: If the bottom edge of the window is less than 18 inches (457 mm) above the finished floor, and the window is large enough, it is considered hazardous.
- Window area: The IRC specifies that if the exposed area of a single pane is greater than 9 square feet (0.84 m²), and the bottom edge is less than 18 inches above the floor, it must be tempered.
- Walking surface proximity: Windows within 36 inches (914 mm) of a walking surface (like a hallway or patio) may also be subject to tempering if they meet the size and height thresholds.
Your 71 x 60 window has an area of 29.6 square feet (2.75 m²), which is well above the 9-square-foot threshold. So if the bottom edge of that window is less than 18 inches from the floor, it must be tempered. If the bottom edge is higher—say, 24 inches or more—then the size alone may not trigger the requirement, depending on your local code.
How to Check Your Local Building Code
Building codes are adopted at the state or local level, and while most follow the IRC for residential construction, there can be amendments. The best way to know for sure is to contact your local building department or a licensed contractor. They can tell you:
- Which code edition is enforced in your area (e.g., 2018 IRC, 2021 IRC).
- Whether any local amendments change the window tempering rules.
- If a permit is required for your window replacement or installation.
If you are replacing an existing window, the code may also require that the new window meet current standards, even if the old one did not. This is common when the window is in a hazardous location.
Common Misconceptions About Tempered Glass
One common misconception is that any large window must be tempered. That is not true—size alone is not the trigger; it is size combined with proximity to the floor or walking surface. Another misconception is that tempered glass is unbreakable. It is stronger, but it can still break from severe impacts or structural stress. It just breaks into safer pieces.
Another point of confusion: laminated glass is sometimes accepted as an alternative to tempered glass in certain hazardous locations. Laminated glass consists of two or more glass layers bonded with a plastic interlayer, so it holds together when shattered. Some codes allow it for windows where tempering is required, but not always—check your local code.
Cost and Practical Considerations
Tempered glass costs more than standard annealed glass—typically 15% to 30% more for the glass itself, plus additional fabrication time. For a 71 x 60 window, the price difference might be $100 to $300, depending on the glass thickness and whether it is insulated (double-pane). However, the cost of not complying with code can be higher: you may face fines, difficulty selling your home, or liability if someone is injured by non-compliant glass.
If you are installing the window yourself, note that tempered glass cannot be cut or modified after it is manufactured. You must order it to the exact size. It also has a slight surface distortion due to the tempering process, which is usually not noticeable but can be in certain lighting.
Alternatives to Tempered Glass
If you are looking for safety glass but want to avoid the cost or distortion of tempering, consider these alternatives:
- Laminated glass: Holds together when broken, provides better sound insulation and UV protection, but is more expensive than tempered.
- Heat-strengthened glass: Twice as strong as annealed but not as strong as tempered; it breaks into larger shards, so it is not considered safety glass.
- Acrylic or polycarbonate: Clear plastics that are impact-resistant, but they scratch easily and are not typically used for standard window glazing.
For most residential windows, tempered glass remains the most cost-effective way to meet safety code requirements.
Frequently Asked Questions
Does a 71 x 60 window need to be tempered if it’s on the second floor?
Yes, if the bottom edge is less than 18 inches above the floor and the window is over 9 square feet, it must be tempered—regardless of the floor level. The risk of falling into the glass exists on any floor.
Can I use regular glass if I put a protective film on the window?
No. Safety film does not make annealed glass compliant with building codes for hazardous locations. The glass itself must be tempered or laminated to meet code requirements.
What if the window is above a bathtub or in a shower?
Windows in bathrooms are subject to additional rules. Any glazing within 60 inches of the bathtub or shower floor must be tempered, regardless of size or height above the floor. So a 71 x 60 window in a bathroom would almost certainly require tempering.
How do I know if my existing window is already tempered?
Look for a small etched mark in one corner of the glass that says “TEMPERED” or “SAFETY GLASS.” If there is no mark, it is likely not tempered. You can also break a small piece (if you are replacing it) to see if it shatters into pebbles.
Does the window’s orientation (e.g., sliding vs. fixed) affect the tempering requirement?
No, the orientation does not change the code requirement. The rules apply to all types of windows—fixed, sliding, casement, or awning—based on the same hazardous location criteria.
What is the maximum size for a non-tempered window?
There is no universal maximum size for non-tempered windows. The code only requires tempering when a window meets the hazardous location criteria (e.g., low to the floor and over 9 square feet). You can have a very large window as long as it is not in a hazardous location.
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