Hurricane Impact Windows and Doors: A Coastal Spec Guide

A hurricane impact window or door is a tested assembly of frame, glass, hardware and anchorage that resists wind-borne debris and then survives thousands of positive and negative pressure cycles without opening the building envelope. Laminated glass is the visible part, but the rating belongs to the whole system as tested. For a coastal project, specify the required design pressure, the impact level and the approval pathway, and verify that each product's documentation covers the exact configuration you are buying.

Why does opening protection matter so much?

When a window or door fails in a hurricane, wind enters the building and internal pressure rises sharply. That pressure adds to the external suction on the roof and leeward walls, and is a major contributor to roof and structural failures. Building codes in hurricane-prone regions therefore require glazed openings in wind-borne debris regions to be either impact-resistant or protected by tested shutters. Impact-rated products remove the need to deploy shutters before a storm and provide everyday benefits: security, sound reduction and UV filtering from the laminated interlayer.

How does laminated glass work in impact glazing?

Laminated glass bonds two or more glass lites with a polymer interlayer. When struck, the glass may crack, but the fragments stay adhered to the interlayer and the lite stays in the frame. The common interlayers are:

• PVB (polyvinyl butyral): the most widely used interlayer, flexible and cost-effective for many residential impact applications.
• Ionoplast (SGP-type) interlayers: stiffer and stronger, which supports larger lites, higher design pressures and better post-breakage stiffness.

Impact glazing is often supplied as laminated insulating glass: a tempered or heat-strengthened outer lite, an air or argon space, and a laminated inner lite. That arrangement keeps the thermal benefits of double glazing while placing the laminate where it protects the interior. The glazing method matters just as much as the glass. The laminate must be captured and bonded in the frame, typically with structural silicone or a tested glazing tape, so that the cracked lite cannot be pulled out under cyclic loading.

What is design pressure and how do you choose it?

Design pressure (DP) is the wind pressure, in pounds per square foot (psf) or pascals, that a product is rated to resist. It is expressed as a positive value (pushing in) and a negative value (suction). The required DP for each opening is calculated from the building code wind provisions, which in the US reference ASCE 7, using basic wind speed, exposure category, building height and the opening's location on the building. Openings near building corners and on upper floors usually see higher suction.

In North America, products tested to the AAMA/WDMA/CSA 101/I.S.2/A440 standard (often called NAFS) carry a Performance Grade that relates to design pressure, along with air and water performance. Do not take a single DP figure for an entire house; ask your engineer or the plan reviewer for a wind-load schedule by elevation and zone, then match products to it.

How are impact windows and doors tested?

Outside Florida's High-Velocity Hurricane Zone, impact performance in the US is typically demonstrated to ASTM E1886 (test method) and ASTM E1996 (specification). The specimen is struck by a missile, then subjected to cyclic pressure loading. Missile levels depend on building elevation and wind speed: large-missile tests use a timber stud fired at the glazing and apply to lower elevations, while small-missile tests use steel balls and apply higher on the building.

Miami-Dade and Broward counties form the High-Velocity Hurricane Zone (HVHZ) in the Florida Building Code, which uses its own Testing Application Standards (TAS 201 for impact, TAS 202 for uniform static air pressure, air and water, and TAS 203 for cyclic loading). Products for the HVHZ generally require a Miami-Dade Notice of Acceptance (NOA).

Requirements differ between states, counties and code editions. Texas, the Carolinas, Louisiana, Hawaii and other coastal areas adopt the International Codes with local amendments, and Australia uses its own cyclone testing approach for regions C and D. Always confirm with the authority having jurisdiction.

What does a product approval actually cover?

An approval or test report lists the tested configurations: maximum unit size, glass make-up, frame and sash profiles, reinforcement, hardware, anchor type and spacing, and the substrate the anchors go into. A product is only approved within those limits. Common reasons for rejection at inspection include:

• Units larger than the maximum tested size.
• Different glass thickness or interlayer than the approval lists.
• Mulled combinations without a tested mullion or mull approval.
• Anchors, embedment or edge distances that do not match the installation instructions.
• Missing permanent labels or required certification marks.

Before you order, request the approval or test documentation for the exact series and check it against your opening schedule. If the documentation does not cover a size, change the size or the product, not the paperwork.

Special considerations for impact doors

Large doors are the hardest openings to rate. Sliding, lift & slide and bi-fold doors must resist missile impact on every panel and hold their interlocks and locking points closed under cyclic suction. Water resistance is equally important: a sill that passes structural testing but leaks under wind-driven rain is a callback. Look at the water test pressure listed on the rating, the sill height, and whether the sill drains to the exterior. Outswing doors are popular in coastal regions because wind pressure pushes the leaf against its stops. Our aluminum door range includes impact-oriented lift & slide, bi-fold and French configurations, and our slim-frame series includes impact-resistant outswing and tilt & turn options for projects that want narrow sightlines.

Impact-rated products or shutters?

Codes generally allow either approach in wind-borne debris regions, so the choice is about cost, operation and use of the building. Shutters can pair with non-impact glazing and may suit budget-driven projects, but someone must deploy them before every storm, and they block light and egress while closed. Impact-rated products protect the opening permanently and require no storm preparation, which is why they dominate in vacation rentals, hotels and homes left unoccupied for parts of the year.

Whichever route you take, the opening must still meet design pressure, air and water requirements in normal service.

Corrosion and coastal durability

Salt spray attacks finishes, fasteners and hardware long before it affects the aluminum itself. For sites close to the shoreline, specify a coastal-grade powder coat or anodized finish, stainless steel or coated fasteners, and hardware with a corrosion resistance appropriate to the exposure. Drainage paths should be open and easy to clean, and EPDM gaskets should be continuous at corners. Plan maintenance: rinsing frames and tracks with fresh water periodically extends the life of finishes and rollers.

A practical specifying checklist

1. Obtain the wind-load schedule for every opening, including corner zones.
2. Confirm whether the site is in a wind-borne debris region and which missile level applies.
3. Identify the approval pathway required: test reports, Florida Product Approval, Miami-Dade NOA or other local approval.
4. Match each opening to a tested size, glass make-up and configuration.
5. Review installation instructions, anchors and substrate requirements with the installer.
6. Specify finishes and hardware for the coastal exposure.

Our engineering team can review your schedule against the documentation available for our impact-oriented series. Contact us with your wind loads and opening sizes, and read our glazing guide for how laminated glass combines with Low-E and gas fills.

Frequently asked questions