Is tempered glass fire resistant?

This blog post will answer the question, “Is tempered glass fire resistant” and cover topics like the fire-resistant properties of tempered glass and frequently asked questions related to the topic.

Is tempered glass fire resistant?

No, tempered glass is not fire resistant. But it is heat resistant.

What is Tempered Glass, and how does it work?

Tempered glass, often known as toughened glass, is 4 to 5 times more powerful than Annealed Glass of the same size and shape and resists thermal shattering.

Tempered glass is created by putting Annealed Glass thru a chemical and thermal tempering process. 

Annealed glass is heated to 700 ℉ in a furnace and then quickly cooled, causing the outer surface of the glass to compress and the inner layer of the glass to expand. Glass’ physical attributes, such as color, clarity, light transmission, & chemical composition, remain constant.

When toughened glass fractures, it shatters into little shards that are less likely to damage people than huge chunks of glass.

Toughened glass is used in situations where there is a greater danger of breakage & contact. Curtain walling, big panels of window glass, frameless doors, & automobile front and back windows all employ it.

The major drawback of Tempered Glass is that it cannot be modified after it has been toughened; all needed holes must be drilled or sizing completed prior to the tempering process.

Tempered Glass: Is it Fire Resistant?

Tempered glass is resistant to heat, but it is not fire-resistant unless it is constructed to be so. The heat rating of standard Tough glass products is quite high; these materials typically fracture at around 500 degrees Fahrenheit. 

However, this is insufficient to assure optimum safety. Fire-resistant glass, on the other hand, is made specifically to withstand extreme temperatures. 

It can resist temps between 1500 and 1600 degrees Fahrenheit, making it a very dependable fire barrier that can stop flames, fire, smoke, and intense radiant & conductive heat from spreading. Using fire-rated glass for doors, for example, may considerably reduce the risk of injury and death.

Heat Resistance of tempered glass

Because of its incredible edge strength, this kind of glass can tolerate uneven and high temps.

Thermal breakage is a risk with annealed glass. The glass expands and contracts at varying rates as a result of direct sunshine or direct sources of heat. Tempered glass has a high edge strength, which makes it resistant to heat breaking.

Tempered Glass: Is it Heat-Proof?

It is not heatproof. Professional tempered glass does offer some fire protection in specific situations. It isn’t suitable for use in heavy-duty situations.

Standard window glass may shatter at temperatures of roughly 250° F, however, tempered glass can withstand temperatures of up to 500° F. 

Tempered glass is a cost-effective solution for lower-temp applications such as fireplace or wood burner doors, even though these temps are nothing near the intensity of a full-blown fire.

When used on a fireplace floor or a wood-burning stove door, ceramic glass gives a higher degree of heat resistance. While ceramic glass may act as a heat barrier, it does not go through the same rigorous testing or obtains the same designation as real fire-rated glass.

What is the Purpose of Tempered Glass?

Tempered glass, sometimes known as “safety glass,” is commonly used in automobile windows, glass tables, as well as other installations that need higher safety requirements.

Tempered glass is more resistant to force due to the manufacturing procedure, but it is not shatterproof or indestructible in any manner. As a result, it shouldn’t be utilized to keep intruders out, although it will withstand greater force than ordinary glass.

Tempered glass is also more resistant to damage at higher temperatures thanks to the tempering process. Tempered glass is often utilized in settings where high temps are likely to shatter glass, such as fireplace windows or kitchen equipment.

What is Fire-Rate Glass, and how does it work?

On the other hand, the fire-rated glass may help keep smoke and flames from spreading from one area to the next. All fire-rated glass acts as a barrier to help limit the spread of smoke and flames in the event of a fire. 

It’s a kind of safety glass that has been proved in a Fire Resistance Test to provide long-term fire protection.

Types of fire-rated glass

The four basic types of fire-rated glazing are as follows:

  • Polished wired glass
  • Ceramic glass
  • Specially tempered glass
  • Transparent wall unit

I will now elaborate on the guidance given above.

Polished wired glass

By far the most well-known product in the business is Polished Wired Glass. It has been in use for over a century and has a proven track record. For many years, wired glass was the only glass that could pass fire testing, therefore most rules were developed around it. 

Wired glass has received a 45-min rating after passing the hose stream test. The wire mesh was readily recognized by code & fire inspectors as an indication that the glass was fire-rated.

However, in certain cases, the same wire mesh has given off an unfavorable “institutional” vibe. People have also made the mistake of thinking that the wire mesh renders the glass more impact-resistant.

Wired glass, on the other hand, is a rather weak glass that barely passes 100 ft./lb. impact criteria. 

Keeping this in mind, even though wired glass is widely accessible and inexpensive, it should be put with caution in situations where impact safety is an issue, such as schools as well as other high-traffic areas. 

With liability concerns in mind, several schools opt for high-impact fire-rated glass, despite the higher initial price.

Ceramic glass

Ceramic glass is a kind of fire-resistant glazing that has only been available for the previous 12 years. Ceramic has long been renowned for its incredible heat & thermal shock resistance. 

As a result, ceramic may now be found in everything from stoves to automobile engines. It didn’t take long after the technology for creating a transparent ceramic product was created to recognize the potential for its usage as a fire-rated glass.

Ceramic glass is transparent and wireless, giving it a significant aesthetic benefit. It comes in a variety of formulations that may give a variety of benefits, such as fire resistance for up to 3 hrs, higher intensity safety ratings, sound suppression, and so on. 

Without impacting the fire rating, it may be beveled, engraved, or sandblasted. It’s also available in energy-efficient insulated glass unit configurations for use in external applications.

Specially tempered glass

For low-level fire safety, specially tempered glass has become a popular option. It’s clear, wireless, and costs a reasonable amount of money to get started. 

It is suited for various door applications due to its high impact ratings. It does, however, have several severe flaws that must be addressed.

The hose stream test is not passed by specially tempered glass, unlike other fire-rated glass materials. In the event of a real fire, if neighboring sprinklers activate and even a tiny quantity of water contacts the hot window, it will most certainly fall out of its frame within mins. 

As a result, it was only able to meet the requirements for a 20-minute rating. 

This sort of material has been mistakenly swapped for wired glass or other higher-performance fire-rated glass when it does not have the same fire rating. This product must not be considered if sprinklers are located near the entrance.

Transparent wall unit

Transparent Wall Units are the last type of fire-rated glass, and they’re in a league of their own. Despite the fact that they are composed of glass, they are examined and designated as “walls.” Its claim to fame is its heat transfer resistance. 

Transparent wall units may really prevent a lot of heat from escaping through the glass. You could physically lay your hand on the opposite side of the glass as a fire burns on one side. 

Transparent wall panels are ideal for situations where people may be stuck for lengthy periods of time, such as stairways, sensitive computer spaces, or areas with wide expanses of glass.

There are several types of these items available on the market. Some are insulated units packed with a transparent gel that becomes opaque in the event of a fire. Others are built of numerous layers of glass with intumescent interlayers that become opaque during a fire. 

Both types of goods have up to 2-hour ratings, can endure a fire hose stream test, and have high impact safety ratings. 

Architects may now use these transparent wall & door modules from floor to ceiling in their designs while still providing two-hour fire protection, thanks to improved farming that is now accessible.

The Benefits of Tempered Glass

Tempered glass makes up the majority of the glass you see on a daily basis. Tempered glass is utilized in a variety of applications, including windows, computers, and doors. 

The following are among the reasons behind this:

  • Strong
  • Safe
  • Heat-resistant
  • Scratch-resistant
  • Versatile

I will now elaborate on the guidance given above.


Tempered glass is about four times stronger than annealed glass, sometimes known as “common” glass. The thermal tempering method that is used to make toughened glass gives it its strength. 

The exterior surface of the glass is compressed during the quenching process (a high-pressure cooling operation). Glass that is compressed is roughly 5 times less likely to shatter than glass that is tensioned.

The final product is toughened glass that can endure direct hits, strong winds, and mild explosions.


Tempered glass is made to be safe. Toughened glass, rather than shattering into sharp shards, fractures into microscopic granules if it is struck by a big enough force. Another reason toughened glass is so extensively used is as a safety measure.


Temps of up to 470 °F may be tolerated by tempered glass. Tempered glass is suitable for kitchen equipment and locations that are often exposed to heat since it is heat resistant.


Toughened glass is scratch-resistant & retains its clarity and brightness thanks to the thermal process that makes it so tough. Tempered glass is used in automobile windows, phone displays, and glass doors for this reason.


Tempered glass comes in a wide range of patterns and designs, making it ideal for use in a number of applications.

Frequently Asked Questions(FAQs), “Is tempered glass fire resistant?”

Is it safe to use tempered glass in a hot environment?

Toughened glass & ceramic glass are the two kinds of glass usually used in fireplaces and wood stoves because of their heat resistance. 

Toughened glass is the less costly option, and it’s excellent for situations where the temp isn’t too high. It can resist temps of up to 470℉ indefinitely.

Is all of the glass fire-resistant?

In actuality, most glass provides little to no fire protection. When the temperature hits about 250° F, for example, conventional window glass will crack. 

Tempered glass can withstand temperatures of up to 500 degrees Fahrenheit. Fire-resistant glass, on the other hand, can withstand temperatures of up to 1600 degrees Fahrenheit.

Is tempered glass resistant to heat?

Tempered glass can endure high and low temperatures. It can withstand being doused with ice-cold water at 300 degrees Celsius. 

Because of its tolerance to extreme temp differences, it may be employed in situations where annealed glass could shatter due to thermal stress.

In fire doors, what kind of glass is used?

The fire-rated glass must be used in all fire-rated doors with glass panels. This is a unique sort of glass that has been engineered to enhance fire resistance.

Is fire capable of shattering glass?

‘Thermal shock’ refers to the quick heating induced by the fire, while ‘thermal stress’ refers to the steep gradient formed.

The glass breaks due to thermal stress. Glass windows are housed in frames with a frame thickness that is more than the glass pane thickness.

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