Architectural glass refers to glass used as one of the fundamental materials in building construction. Typically, glass is applied as a transparent material in windows and façades, but it is also widely used in interior design, such as in glass partitions, railings, balustrades, staircases, wall claddings, and more
The diversity of glass in terms of size, color, patterns, and textures allows designers to create innovative, functional, and safe spaces
Among all its features, safety is the greatest concern for both designers and users. To enhance safety and minimize the risks of injury caused by glass breakage, tempered (fully toughened), heat-strengthened, and laminated glass are commonly used
Today, float glass—produced through the float process—is the most widely used raw material in glass processing plants and is considered the base product in both the glass and construction industries
Annealed glass is free from internal stresses caused by thermal processing. Upon breakage, it shatters into large, sharp pieces that can cause severe injuries
In many regions worldwide, building codes prohibit the use of annealed glass in applications where its breakage could pose risks to people—such as in bathrooms, glass doors, emergency exits, and in low-level areas of homes and schools
Tempered glass is one of the most essential and widely used glass products. It is manufactured by heating annealed float glass to around 700°C and then rapidly cooling it in special furnaces
This thermal process rearranges the molecular structure, creating high surface compression and tension between the inner and outer layers of the glass, which significantly enhances its strength and safety.
Key Features of Tempered Glass
| Property | Tempered Glass |
|---|---|
| Resistance to thermal shock | up to 250°C |
| Mechanical strength | 4–5 times stronger than annealed glass |
| Tensile strength | ~65 MPa |
| Flexural strength | 120–200 N/mm² |
| Surface compression | >95 MPa |
| Allowable stress for construction | 50 MPa |
| Breakage pattern | Small blunt-edged fragments |
| Post-treatment processing | Not possible after tempering |
Tempered glass is five times stronger than annealed glass in terms of thermal and mechanical resistance
In case of breakage, it fragments into small, blunt pieces with reduced cutting risk, making it a safety glass
Its optical properties (light transmission, solar performance) remain unchanged
It cannot be cut, drilled, or processed after tempering—such operations must be completed beforehand
One potential drawback is spontaneous breakage (nickel sulfide inclusion), which occurs when impurities expand under temperature changes
Applications
Tempered glass is widely used in architecture and construction (façades, curtain walls, windows, glass doors, railings, staircases, wall claddings, partitions, shower cabins, counters, and showcases), as well as in automotive and appliance industries (oven doors, refrigerator shelves, fireplace screens, etc.)
Heat-strengthened glass is manufactured similarly to tempered glass but cooled at a slower rate. Annealed glass is heated to around 650–700°C, but the gradual cooling process results in lower surface stress compared to fully tempered glass
When comparing annealed and heat-strengthened glass of equal thickness and size, the heat-strengthened version is about twice as strong
Key Features of Heat-Strengthened Glass
| Property | Heat-Strengthened Glass |
|---|---|
| Resistance to thermal shock | up to 130°C |
| Mechanical strength | ~2× stronger than annealed glass |
| Tensile strength | 40–55 MPa |
| Flexural strength | ~40 N/mm² |
| Allowable stress for construction | 17 MPa |
| Breakage pattern | Larger fragments than tempered glass, smaller than annealed |
Advantages
1.6–2× stronger than annealed glass
Good optical quality (flatness and light transmission close to annealed glass)
Greater thermal resistance (up to ~100°C temperature difference)
Lower risk of spontaneous breakage compared to tempered glass
Less distortion (warping/waves) due to slower cooling
Applications
The breakage pattern of heat-strengthened glass makes it ideal for skylights, canopies, and laminated structures—since fragments adhere to interlayers instead of falling
It is also used in security glazing applications, such as anti-vandal and bullet-resistant glass
