Hurricane impact resistant glass
Hurricane impact resistant glass
This guide explains what hurricane impact glass is, where it’s required by building codes, how it’s tested for strength and safety, and why it can be a smart choice for helping to protect coastal homes and buildings from storm damage.
- What is hurricane impact glass
- What are the benefits of hurricane impact glass?
- Where are hurricane resistant windows required?
- Which building codes apply to hurricane impact systems?
- How is hurricane impact glass tested?
- What types of glass are used for hurricane resistant windows?
- How thick should hurricane window glass be?
- Does hurricane impact glass also improve energy efficiency?
What is hurricane impact resistant glass?
Hurricane impact resistant glass is specially designed to help withstand the force of windborne debris during severe storms. When hurricanes hit coastal areas, flying objects can break standard windows, causing sudden internal pressure and water leaks. This can lead to severe structural damage. Impact glass can protect your home or building by helping to keep the “building envelope” intact.
What are the benefits of hurricane impact glass?
Main benefit: Hurricane impact glass provides protection against dangerous windborne debris during hurricanes, helping to keep the building envelope intact and maintain structural integrity.
Additional benefits:
- Helps reduce water intrusion and interior damage during storms.
- Offers year-round security benefits by making it more difficult for intruders to break through windows (compared to windows with non-laminated glass).
- Can provide energy-efficiency when combined with low-E coatings and tinted glass.
Where are hurricane resistant windows required?
In the United States, building codes require hurricane resistant windows or protective coverings in areas called “wind-borne debris areas”.
This generally includes:
- Areas within 1 mile of the coastal mean high-water line where the basic design wind speed is 130 mph or more.
- Areas where the basic design wind speed is 140 mph or more.
Large missile impact resistant products are required for glazing located within 30 feet above grade, while small missile impact resistant products are required for glazing located more than 30 feet above grade.
Large missile impact resistant products are required for glazing located within 30 feet above grade, while small missile impact resistant products are required for glazing located more than 30 feet above grade.
Which building codes apply to hurricane impact systems?
Hurricane impact systems – including the glazing, frame, and anchorages – must meet specific building code requirements, which can vary by location. In wind-borne debris coastal areas, the International Building Code (IBC) requires windows and doors to be impact resistant or protected with impact-resistant coverings. The code requires impact systems to be successfully tested according to:
- ASTM E1996 (Standard Specification for Performance of Exterior Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Windborne Debris in Hurricanes)
- ASTM E1886 (Standard Test method for Performance of Exterior Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Missiles(s) and Exposed to Cyclic Pressure Differentials).
In Miami-Dade and Broward Counties in Florida, products must comply with the Florida Building Code testing standards: TAS 201 (Impact Test Procedures), TAS 202 (Criteria for Testing Impact & Nonimpact Resistant Building Envelope Components Using Uniform Static Air Pressure), and TAS 203 (Criteria For Testing Procedures Subject to Cyclic Wind Pressure Loading).
How is hurricane impact resistant glazing tested?
Glazing systems (glass, frame, and anchorage) must pass rigorous tests to prove it can resist both impact and high wind pressure.
- Large missile impact test: a glazing system must withstand a piece of 2” x 4” (51 mm x 102 mm) timber at a specific weight and impact speed without penetration. After the testing, the glazing system is subjected to cyclic pressure loading to simulate a hurricane windstorm.
- Small missile impact test: a glazing system must successfully handle impact from 2-gram solid steel balls at a speed of 130 feet per second. Similar to the large missile impact test, the glazing system is subsequently subject to cyclic pressure loading.
What types of glass are used for hurricane resistant windows?
Hurricane resistant windows primarily use laminated glass—two or more panes bonded together with a plastic interlayer. If broken, the glass fragments tend to stick to the interlayer, helping to prevent dangerous shards, wind, and water from entering.
Options include:
- Monolithic laminated glass – a single laminated glass pane.
- Insulating glass units (IGUs) with laminated glass and a high–performance low-E coating – for better thermal performance. The laminated glass can be positioned either:
- facing the interior of the building – most specified and preferred option for building occupant protection from glass shards upon debris impacts.
- facing the exterior of the building – sometimes used to support specific performance of framing systems and impact protection.
How thick should hurricane laminated glass be?
The total thickness of the laminated glass can vary, but commonly specified interlayer thickness is:
- at least 0.060 inch (1.52 mm) interlayer for small missile impact resistance.
- at least 0.090 inch (2.29 mm) interlayer thickness for large missile impact resistance.
Does hurricane impact glass also improve energy efficiency?
Hurricane impact glass can also contribute to energy efficiency when combined with low-E coatings to help reduce solar heat gain and improve thermal insulation. Tinted glass can also be used in combination with low-E coatings to further reduce glare and solar heat gain. These enhancements don’t affect the glass’ ability to resist hurricane debris, but they can help to improve occupants’ comfort and to lower energy demand.