Impact Glass Calculator

Strength in Layers

Move the wind speed slider and watch glass layers stack up. Higher winds need thicker glass. Each layer adds protection against flying debris.

7/16

inch total thickness

Adjust Parameters

Wind Speed 185 mph

Window Width (inches) 36"

Window Height (inches) 48"

Glass Type

Design Pressure 62 PSF

Impact Glass Types

Different constructions for different needs. All must have Miami-Dade NOA approval.

Standard Laminated

5/16" - 7/16" thickness

Two glass panes bonded with PVB interlayer. The most common choice for residential windows. Good impact resistance at reasonable cost.

Insulated Laminated

7/8" - 1" thickness

Laminated unit plus air space and additional pane. Better energy efficiency plus impact protection. Costs more but saves on AC.

SGP Interlayer

5/16" - 9/16" thickness

SentryGlas Plus interlayer is 5x stiffer and 100x stronger than PVB. Better for large spans and extreme conditions. Premium option.

Frequently Asked Questions

Common questions about impact glass in Miami-Dade

What glass thickness is required in Miami-Dade HVHZ?

Glass thickness in HVHZ depends on window size, design pressure, and product type. Typical impact glass for residential use is 5/16 inch laminated (two 1/8 inch panes with interlayer). Larger windows or higher pressures may require 7/16 inch or thicker laminated assemblies. Always check the product's NOA for rated pressure and maximum size.

What is the difference between impact glass and regular glass?

Impact glass is laminated - two or more glass panes bonded with a plastic interlayer (usually PVB or SGP). When hit by debris, the interlayer holds broken pieces together instead of shattering into the building. Regular glass offers no impact protection and is not permitted in HVHZ. Think of it like a car windshield that cracks but doesn't shatter.

Do I need impact glass everywhere in Miami-Dade?

Yes, all glazed openings in Miami-Dade HVHZ must have impact protection - either impact-rated glass or approved shutters. This includes windows, doors, skylights, and any glass enclosure. Every product needs a Miami-Dade NOA (Notice of Acceptance). No exceptions - if wind can reach it, it needs protection.

What are the impact tests for Miami-Dade approval?

Miami-Dade requires two impact tests: Large missile test (9-pound 2x4 lumber shot at 50 feet per second) and small missile test (10 ball bearings at 80 feet per second). After impact, the glass must still resist cyclic pressure loading without allowing water intrusion. These are the toughest glazing tests in the country.