Types of Glass for Custom Doors & Windows: The Ultimate Guide

Key Takeaways

• Low-E glass provides the best combination of improved thermal performance and UV protection, while gas-filled and tinted glass also offer benefits in these areas. Regular glass lacks any special thermal or UV properties.
• Tempered, laminated, and impact resistant glass are the clear leaders in terms of increased strength and safety/impact resistance. These glass types are designed to break into safer pieces or hold together when shattered, reducing the risk of injury. The other glass types do not have these enhanced strength and safety features.
• Tinted, obscured, and spandrel glass provide decorative and aesthetic benefits, with obscured and spandrel glass also offering opacity for privacy or concealment purposes. Low-iron glass has a neutral, colorless appearance. The remaining glass types are primarily transparent and lack special decorative properties.
• At Panda Windows & Doors, we can help you choose the best glass types for your residential and commercial projects.

Low-E Glass

Low-E (Low Emissivity) glass is a type of glass coated with a thin, transparent metallic layer designed to minimize ultraviolet (UV) and infrared (IR) light transmission while allowing visible light to pass through. This coating reduces heat transfer, reflecting heat back into the home during winter and blocking it during summer, thus maintaining a comfortable indoor temperature.

Here’s how low-e glass works (image courtesy of Energy Education).

Manufacturing Process of Low-E Glass

Low-E glass is created using different techniques depending on the type of coating:

1. Hard Coat Low-E: This type is made by applying a thin layer of metallic oxide to the glass during the float process. The coating is fused onto the glass as it cools down.
2. Soft Coat Low-E: This type is produced by depositing multiple thin metallic layers in a vacuum. The coating is applied after the glass has cooled down and is then enclosed within a double-glazed unit for added performance.

Unique Properties of Low-E Glass

1. Thermal Performance: Low-E glass reduces heat loss by reflecting long-wave infrared energy, which helps keep homes warm in the winter and cool in the summer. This results in significant energy savings and improved indoor comfort.
2. UV Protection: The coating prevents UV rays from entering the home, which helps protect furniture, flooring, and upholstery from fading and damage.
3. Invisibility: The coating is almost imperceptible, ensuring that the glass remains transparent and does not affect the aesthetic appeal of the home

These unique properties make low-E glass suitable for regions with extreme climates. It also offers excellent insulation, reducing condensation and moisture buildup, which helps prevent dampness and mold issues.

Gas Filled Glass

Gas-filled glass is a type of glass that enhances insulation by filling the space between two glass panes with a gas, typically argon or krypton. Xenon is also used but it’s very expensive compared to the other two and is usually used for commercial buildings where the budget is higher.

The manufacturing process involves cleaning and coating the glass panes with a low-emissivity layer to reflect heat. The edges of the panes are then sealed to create an airtight space, which is filled with the chosen gas. This gas filling is pumped into the unit and sealed to prevent leaks, ensuring that the gas remains trapped between the panes for optimal performance.

Here’s how gas-filled glass works (image courtesy of Cosyhomes Windows).

Gas-filled glass can be further categorized into two types which are: 

• Double-Glazed Glass: Also known as double-paned glass, this type is similar to gas-filled glass if it’s also filled with inert gasses instead of just air.
• Triple-Glazed Glass: Also known as triple-paned glass, these glass units have three panes of glass, compared to the two panes in double-glazed glass.

The differences between double-glazed and triple-glazed glass (image courtesy of GreenMatch).

Unique Properties of Gas-Filled Glass

1. Improved Thermal Performance: The gas fill (typically argon or krypton) reduces heat transfer through the window, keeping homes warmer in winter and cooler in summer. This leads to energy savings and improved indoor comfort.
2. Enhanced Insulation: The dense, slow-moving gas molecules provide better insulation compared to regular air, reducing heat loss and gain.
3. Reduced Noise Transmission: The gas fill helps absorb sound waves, making the windows more effective at blocking outside noise.
4. UV Protection: Gas-filled windows can help protect furniture and interior furnishings from fading caused by UV rays.

This glass is ideal for improving energy efficiency, reducing noise, and protecting against UV rays in both new constructions and retrofit installations. One thing to keep in mind is that glass with more glazing or panes tend to be thicker and may not be suitable for all projects.

Tempered Glass

Tempered glass–a type of safety glass–is produced by heating annealed glass to approximately 700°C and then rapidly cooling it. This process, known as thermal tempering, puts the glass surface into compression and the core into tension, significantly increasing its strength and impact resistance.

This is how tempered glass looks when shattered tempered glass (image courtesy of Christian Thoni).

Unique Properties of Tempered Glass

1. Strength: Tempered glass is 3 to 7 times stronger than regular annealed glass, making it suitable for more demanding applications. 
2. Impact Resistance: Tempered glass has very high impact resistance, allowing it to withstand extreme conditions and temperatures. 
3. Thermal Resistance: Tempered glass can withstand high temperature changes of up to 250°C, making it suitable for applications like ovens and fireplaces. 
4. Safety: When tempered glass breaks, it shatters into small, rounded pieces rather than sharp shards, reducing the risk of injury. 
5. Optical Quality: The tempering process causes some minor optical distortions, but tempered glass remains transparent. 

Tempered glass is commonly used in areas where safety is a concern, such as in shower doors, glass doors, and windows near floor level. It is also used in vehicles, glass railings, food service equipment, and commercial buildings where both strength and safety are paramount.

Laminated Glass

Laminated glass consists of two or more layers of glass bonded together with one or more thin polymer interlayers, typically made from materials such as polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or thermoplastic polyurethane (TPU). 

The layers are fused through a combination of heat and pressure, creating a single, sturdy sheet of glass. This manufacturing process enhances the glass’s durability and performance –  making it a reliable option for various applications.

The difference in shatter pattern between annealed, tempered, and laminated glass (image courtesy of Destin Glass).

Unique Properties of Laminated Glass

1. Safety: When laminated glass breaks, the glass shards adhere to the plastic interlayer, reducing the risk of injury from sharp edges.
2. Security: Laminated glass is difficult to pierce and can help prevent forced entry.
3. UV Protection: The interlayer can block up to 99.9% of UV rays, protecting interior furnishings from fading.
4. Sound Insulation: Laminated glass significantly improves sound attenuation compared to monolithic glass of the same thickness.

Commonly used in automotive applications for windshields and side windows, laminated glass is also favored in architecture for skylights, overhead glazing, and security glass. Its acoustic properties make it ideal for noise reduction in both residential and commercial buildings, while its UV protection benefits are utilized to protect interiors from sun damage.

Impact Resistant Glass

Impact-resistant glass is made by sandwiching a tough interlayer, usually made of polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA), between two or more layers of glass. This interlayer holds the glass together even when it is broken, providing an additional layer of protection.

The manufacturing process involves heating the glass and interlayer assembly in an autoclave, which applies heat and pressure to bond the layers together. This creates a strong, durable glass that can withstand high impacts.

A cross-section image of impact-resistant glass (image courtesy of Burglar Proof Windows).

Unique Properties of Impact-Resistant Glass

1. Strength: Impact-resistant glass is significantly stronger than regular annealed glass, typically 3-7 times stronger.
2. Impact Resistance: It can withstand high-force impacts without shattering, protecting against damage from debris and forced entry.
3. Safety: When impact-resistant glass breaks, it shatters into small, rounded pieces rather than sharp shards, reducing the risk of injury.
4. Security: The glass remains intact and in the frame even when cracked or damaged, helping to deter forced entry.
5. UV Protection: Laminated impact-resistant glass can block up to 99.9% of UV rays, protecting interior furnishings.
6. Sound Insulation: Laminated impact-resistant glass significantly improves sound attenuation compared to regular glass.

Common use cases include residential windows and doors, especially in hurricane-prone areas, commercial building facades, automotive windshields, and safety applications in furniture and appliances.

One of our door systems–Residential Hurricane-Rated IMPACT IS.14 Lift & Slide–is made from glass that withstand Category 5 hurricanes and large missiles.

Tinted Glass

Tinted glass is designed to reduce solar heat and visible light entering a building or vehicle. It is manufactured using several methods: 

• Dyed tinted glass incorporates a layer of dye between the glass and a protective polyester coating, absorbing solar energy. 
• Metalized tinted glass includes tiny metallic particles to reflect heat and UV rays. 
• Hybrid tinted glass combines the properties of dyed and metalized glass, providing superior heat reduction, glare control, and UV protection.
• Ceramic tinted glass contains ceramic particles that block UV and infrared light without compromising visibility, offering the highest performance level.

Different varieties of tinted glass (image courtesy of Testronix Instruments).

Unique Properties of Tinted Glass

1. Solar Control: Tinted glass absorbs and reduces the amount of solar heat and visible light entering a building or vehicle, helping to regulate indoor temperatures.
2. UV Protection: Tinted glass blocks a significant portion of harmful UV rays, protecting interior furnishings and occupants from fading and damage.
3. Aesthetic Appeal: Tinted glass is available in a variety of colors like bronze, green, blue, and grey, allowing it to enhance the visual appeal of buildings and vehicles.
4. Privacy and Security: Tinted glass makes it more difficult to see through, providing enhanced privacy and deterring potential intruders.

Tinted glass is commonly used in buildings for windows, curtain walls, skylights, and interior partitions; in vehicles for windshields, side windows, and sunroofs; and in furniture and appliances for display cases and tabletops. It is also used in aerospace for aircraft windows to manage heat and glare.

Obscure Glass

Obscure glass is treated to reduce transparency and distort or conceal the view through it – providing privacy while still allowing light to pass through. The manufacturing process includes various techniques depending on the types of obscure glass available which are: 

• Frosted Glass
• Ribbed/Reeded Glass
• Patterned Glass
• Bubble Effect/Raindrop Glass
• Glue Chip Glass

Glue Chip Glass is made by applying and chipping away glue on sandblasted glass.

Unique Properties of Obscure Glass

1. Varying levels of opacity: Obscured glass can range from slightly diffused to completely opaque, allowing for different degrees of privacy.
2. Light transmission: It still allows natural light to flow through, creating a balance between privacy and illumination.
3. Decorative appeal: Obscured glass can add a stylish, decorative element to a space while providing privacy.

Obscured glass is commonly used in interior design for shower enclosures, room partitions, glass furniture tops, bathroom windows, interior doors, and decorative features. In architecture, it serves for exterior windows, facades, and balustrades. 

In commercial settings, it is utilized for signage, decorative panels, office partitions, meeting rooms, and lighting fixtures, and it is also used in historic buildings for ground-level windows, bathroom windows, and privacy partitions.

Spandrel Glass

Spandrel glass is an opaque glass used to conceal building elements such as vents, wires, slab ends, and mechanical equipment between floors. Unlike transparent vision glass, spandrel glass is specifically designed to be non-vision, effectively hiding these components from view. 

The manufacturing process involves coating the glass with an opacifier, usually a silicone-based paint or ceramic frit, to create the opaque effect. The glass is then heat-treated, typically by tempering, to enhance its strength and thermal resistance. Often, spandrel glass is fabricated into insulated glass units (IGUs) to improve thermal and sound insulation.

Spandrel glass is usually more opaque than vision glass on a building (image courtesy of Willowbrook).

Unique Properties of Spandrel Glass

1. Opaque appearance: Spandrel glass has an opaque surface that prevents visibility through the glass.
2. Heat treatment: All spandrel glass must be heat-treated, usually by tempering, to resist thermal stresses.
3. Customizable colors: Spandrel glass is available in a wide range of colors to match or complement the vision glass and building facade

It is commonly used in commercial building facades to create a seamless all-glass look while concealing unsightly building components. Additionally, spandrel glass can serve as a decorative feature by incorporating various colors, patterns, or etched designs, enhancing the overall aesthetic of the building facade.

Regular or Annealed Glass

Regular glass, also known as annealed, standard or float glass, is the basic form of flat glass widely used in various applications. It is manufactured by melting raw materials such as sand, soda ash, and limestone in a furnace at high temperatures. 

The molten glass is then poured onto a large, flat surface and allowed to cool slowly in a controlled environment, a process known as annealing. This gradual cooling relieves internal stresses in the glass, enhancing its durability and strength.

The image above shows the basic process of producing regular glass (image courtesy of AIS Glass).

Unique Properties of Annealed Glass

1. Flexibility: Annealed glass can be easily cut, drilled, and fabricated into various shapes and sizes.
2. Optical Quality: Annealed glass has a high level of optical clarity and transparency with minimal distortion.
3. Cost-Effectiveness: Annealed glass is generally the most affordable type of glass due to its basic manufacturing process.

Common use cases include residential and commercial windows, tabletops, shelves, automotive side and rear windows, mirrors, and decorative applications where it can be etched, painted, or laminated to create aesthetic features.

Low-Iron Glass

Low-iron glass, known for its exceptional clarity and transparency, is produced using raw materials with very low iron content, typically less than 0.01% iron oxide. 

The manufacturing process involves the standard float glass method, where molten glass is poured onto a large, flat surface and slowly cooled. 

The reduced iron content eliminates the greenish-blue tint present in regular float glass, resulting in a more neutral and colorless appearance, especially at the edges.

The difference in tint between standard clear glass and low-iron glass (image courtesy of Nathan Allan Glass Studio).

Unique Properties of Low-Iron Glass

1. High Clarity and Transparency: Low-iron glass has a very low iron content, which removes the greenish-blue tint seen in regular glass. This results in exceptional clarity and transparency.
2. High Light Transmission: The reduced iron content allows low-iron glass to have up to 8% higher light transmission compared to standard float glass.
3. Neutral Color: The lack of iron gives low-iron glass a more neutral, colorless appearance, especially at the edges.
4. Versatility: Low-iron glass can be further processed into tempered, laminated, coated, or other specialty glass products.

The high light transmission also makes it a preferred choice for solar panel cover glass, as it maximizes the efficiency of solar energy capture. 

Additionally, low-iron glass is used in furniture and decor, such as tabletops, shelves, and mirrors, where a clean, neutral appearance is important. Its exceptional clarity also makes it suitable for aquariums and display cases, ensuring that the contents are clearly visible. 

Comparison Between Glass Types

Now, here’s a comparison table to clearly see the differences between these glass types:

Table comparing the main features of glass types. 

Choose Panda Windows & Doors for Custom Glass Solutions

Panda Windows & Doors is the go-to choice for many homeowners and businesses for custom glass solutions. With over 30 years of experience in the industry, we have a wide range of high-quality windows and door systems that can be customized with various glass types, finishes, hardware, and so on.

Contact us to learn more about our glass options available for your custom doors and windows.

Frequently Asked Questions (FAQ)

What is the most energy-efficient type of glass?

Low-E glass is the most energy-efficient type of glass. It minimizes heat loss and gain, helping to maintain a consistent indoor temperature and reduce energy bills.

Can I replace only the glass in my windows?

Yes, you can replace only the glass in your windows. However, it’s important to make sure that the new glass is compatible with your existing window frame and meets your specific needs. 

How do I clean and maintain different types of glass?

To clean and maintain different types of glass, use a soft cloth or sponge with a mild detergent and water. Avoid using abrasive cleaners or tools that can scratch the glass. For Low-E and coated glass, follow the manufacturer’s cleaning instructions to avoid damaging the coating.

What is the difference between tempered and laminated glass?

Tempered glass is heat-treated to increase its strength and shatters into small, less harmful pieces when broken. 

Laminated glass consists of two or more layers of glass bonded together with an interlayer, which holds the glass together when shattered, providing enhanced safety and security.