Impact-resistant glass (the most common "hurricane-resistant glass")
This type of glass is laminated glass, which is made by firmly bonding multiple layers of glass with an intermediate layer. The thickness varies greatly depending on the protection level, glass size and design requirements.
Typical structure (from outside to inside) :
Outer layer glass: Usually tempered glass, with a thickness typically ranging from 3mm to 6mm.
Intermediate layer: The key component is a multi-layer polyvinyl acetal (PVB) film or an ionic intermediate layer (such as SGP, which has higher strength). When impacted, even if the glass shatters, the fragments will be firmly held together by this tough adhesive layer, will not fly, and will maintain the overall integrity. The total thickness of the middle layer is the key to determining the impact resistance, usually ranging from 0.76mm (common) to 2.28mm, 3.04mm or even thicker for multiple layers.
Inner glass: It can be tempered glass or annealed glass, with a thickness comparable to or slightly thicker than that of the outer layer.
Reference range for total thickness
Common small Windows for residential use: The total thickness is approximately between 7mm and 15mm (for example: 3mm glass + 0.76mm PVB + 3mm glass ≈ 6.76mm total thickness).
Large floor-to-ceiling Windows or high-standard commercial buildings: The total thickness can reach 25mm to 50mm or more. It may use three pieces of glass with two layers of PVB (such as 6mm+1.52mm+6mm+1.52mm+6mm), or use a thicker single piece of glass and an intermediate layer.
The key point is that the protective performance does not merely depend on the total thickness of the glass, but more on the thickness and type of the middle layer as well as the certification level of the overall design.
2. Windproof roller shutters/protective plates
This is not glass but an additional protective layer installed outside the window before a hurricane arrives.
Materials: aluminum alloy, polycarbonate sheet, steel roller blinds, etc.
Thickness: Taking polycarbonate (bulletproof plastic) plates as an example, the thickness used for hurricane protection is usually between 3mm and 10mm. The thickness of the metal roller shutter or plate is designed based on the strength of the material.
Determining factors and criteria
The specifications of "hurricane-resistant glass" are not arbitrarily determined but must comply with strict building codes and testing standards.
Test standards: In the United States, the main standards followed are ASTM E1886 and ASTM E1996. It needs to pass through simultaneously:
Wind pressure resistance test: Simulate positive and negative wind pressure at the hurricane level (such as the pressure generated by wind speeds above 200 kilometers per hour).
Impact resistance test: Use a "missile" of a specific weight (such as 2x4 wood) to repeatedly impact the glass surface at a specific speed (such as more than 15 meters per second).
Protection level: Based on the test results, the product will be classified into different levels (such as large missile impact level and small missile impact level), and be suitable for different risk areas (the requirements for the first row of houses along the coast and inland houses are different).
Design impact: The larger the size of the window, the higher the thickness and strength of the glass required. The frame must also be equally sturdy.
Summary
There is no uniform thickness: The thickness of "hurricane-resistant glass" ranges from approximately 7mm to over 50mm, making it a customized engineering product.
The core is the sandwich structure: its essence is multi-layer laminated glass, relying on a tough PVB/SGP intermediate layer to hold fragments together, resist impact and maintain integrity.
It is necessary to check the certification: When purchasing, do not only look at the thickness. The most crucial thing is to confirm whether the product has passed the hurricane impact test of an officially certified laboratory (such as the test approval of Miami-Dade County) and complies with the requirements of local building regulations.
If you need to install for your own house, the best practice is to consult a professional door and window supplier or architect. They will recommend suitable products that meet the corresponding protection level certification based on the geographical location of your house, the size of the Windows and your budget.
