Laminated Glass
Laminated glass is a safety glass that consists of two or more layers of glass bonded together with an interlayer, typically made of polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). When broken, the interlayer holds the glass fragments together, reducing the risk of injury and providing continued protection.
Composition
Laminated glass consists of two or more layers of glass permanently bonded together with one or more plastic interlayers. The most common interlayer is polyvinyl butyral (PVB), a flexible, resilient plastic film that adheres to the glass when heated and pressurized. Other interlayer materials include ionoplast (such as SentryGlas), ethylene-vinyl acetate (EVA), and resin. The interlayer thickness typically ranges from 0.38mm to 1.52mm, with thicker interlayers providing enhanced performance. The glass layers can be annealed, heat-strengthened, or fully tempered, depending on the application requirements. The lamination process involves cleaning the glass, positioning the interlayer between glass layers, removing air, and then applying heat and pressure in an autoclave to create a permanent bond.
Properties
Safety Performance
Holds fragments together when broken
When laminated glass breaks, the interlayer holds the glass fragments in place, preventing them from falling and reducing the risk of injury. This property makes it a safety glass that meets building code requirements for hazardous locations.
Sound Attenuation
Up to 3-5 dB improvement over single glazing
The viscoelastic PVB interlayer dampens sound vibrations, reducing sound transmission through the glass. Specialized acoustic PVB interlayers can provide even greater sound reduction, making laminated glass ideal for noise control applications.
UV Filtration
Blocks 99% of UV radiation with standard PVB
Standard PVB interlayers block up to 99% of ultraviolet radiation, protecting interior furnishings, artwork, and finishes from UV damage and fading. This property is particularly valuable in museum displays, storefronts, and residential applications.
Security Performance
Varies by thickness and interlayer type
Laminated glass provides forced entry resistance, with performance varying based on glass and interlayer thickness. Multiple layers and specialized interlayers like ionoplast provide enhanced security, including bullet resistance in appropriate configurations.
Impact Resistance
High with proper configuration
Laminated glass can be engineered to resist impacts from windborne debris, making it suitable for hurricane-prone regions. Various impact ratings are available based on testing standards like ASTM E1886/E1996 for hurricane resistance.
Post-breakage Performance
Maintains integrity after breakage
Even when broken, laminated glass remains in the frame and continues to provide a barrier. This property is crucial for overhead glazing, balustrades, and security applications where continued protection is required after glass breakage.
Applications
Safety and Security Glazing
Laminated glass is widely used in applications where safety and security are paramount. In residential buildings, it's used for large windows, sliding doors, and skylights to reduce injury risk and prevent fall-through. In commercial settings, it serves as storefront glazing, entrance doors, and interior partitions. Security applications include bank teller windows, jewelry display cases, and high-security facilities. Multiple layers of glass and thicker interlayers provide enhanced security, with specialized configurations offering bullet and blast resistance for government buildings, embassies, and high-risk facilities.
Overhead and Structural Glazing
Building codes typically require laminated glass for overhead applications such as skylights, canopies, and glass roofs due to its post-breakage integrity. Even when broken, the glass remains in place, preventing dangerous falling fragments. In structural applications, laminated glass is used for glass floors, stairs, and bridges, often in combination with tempered glass for additional strength. The glass can be designed to support significant loads while maintaining transparency, creating dramatic architectural features with built-in safety.
Sound Control Applications
Laminated glass with acoustic interlayers is used in sound-sensitive environments such as recording studios, conference rooms, hotels, and residential buildings near noise sources like airports or highways. The specialized interlayers are engineered to dampen sound waves across various frequencies, providing significant noise reduction compared to standard glazing. Multi-layer configurations with varying glass thicknesses can be designed to target specific frequency ranges for optimal acoustic performance.
Hurricane and Impact Resistance
In coastal regions and hurricane-prone areas, building codes often require impact-resistant glazing. Laminated glass with thicker interlayers (typically 0.90mm or greater) is tested and certified to withstand impacts from windborne debris during storms. These systems help maintain the building envelope during severe weather, preventing internal pressurization that can lead to structural failure. The glass may break upon impact, but the interlayer keeps the opening sealed against wind and water intrusion.
UV Protection and Museum Applications
The UV-filtering properties of laminated glass make it ideal for protecting sensitive items from sun damage. Museums use laminated glass for display cases and windows to protect artifacts and artwork from harmful UV radiation. Retail storefronts use it to prevent merchandise fading, and residential applications include picture windows where furniture and flooring protection is desired. Specialized museum-grade laminates can block up to 99.9% of UV radiation while maintaining excellent visible light transmission and color rendering.
Decorative and Privacy Applications
Laminated glass offers extensive decorative possibilities by incorporating colored interlayers, fabric, metal mesh, or printed films between the glass layers. These decorative laminates can create privacy screens, artistic features, and branded elements while maintaining the safety benefits of laminated glass. Digital printing technology allows for high-resolution images or patterns to be permanently embedded in the interlayer. Switchable privacy glass, which changes from transparent to opaque with electrical current, often uses laminated glass as its base structure.
Advantages
- Enhanced safety with fragments remaining adhered to the interlayer when broken
- Excellent sound attenuation properties, especially with acoustic interlayers
- Blocks 99% of UV radiation, protecting interiors from fading
- Provides security and forced entry resistance
- Maintains integrity and continues to provide a barrier even when broken
- Available in various configurations for hurricane and impact resistance
- Can be combined with other glass types (tempered, low-e) for enhanced performance
- Offers decorative options with colored or printed interlayers
Limitations
- Higher cost than single-pane glass (typically 50-100% more expensive)
- Heavier than single-pane glass of the same thickness
- Edge exposure to moisture can cause delamination over time
- More complex installation requirements
- Potential for bubbling or edge separation if improperly installed
- Limited repairability if damaged
- Requires special cutting and processing equipment
- PVB interlayers are difficult to separate for recycling
Sustainability Profile
Laminated glass has a moderate sustainability profile. The manufacturing process requires more energy than standard glass due to the additional materials and processing steps. However, the extended service life, safety benefits, and potential energy savings contribute positively to its overall environmental impact. PVB interlayers are difficult to separate from glass for recycling, though some specialized facilities can process laminated glass waste. The UV-filtering properties can reduce solar heat gain, potentially lowering cooling costs in buildings. When specifying laminated glass, look for manufacturers with environmental certifications and those who have programs for recycling production waste. Some manufacturers now offer bio-based interlayers with reduced environmental impact compared to traditional PVB. The durability and multi-functionality of laminated glass (combining safety, security, acoustics, and UV protection) can reduce the need for multiple building components, contributing to resource efficiency.