Impact window ratings, explained

The ratings on an impact window are not marketing. They are how the Florida Building Code and your insurer decide whether a product actually protects an opening, and they are how you compare quotes in Sarasota and Manatee County on equal terms. This guide translates the alphabet soup, NOA, Florida Product Approval, ASTM E1886 and E1996, and DP, into plain language you can use when you read an estimate.

Two approvals: NOA and Florida Product Approval

Every impact product sold for a Florida opening carries an approval. The Miami-Dade Notice of Acceptance, or NOA, is the strictest, written for the High Velocity Hurricane Zone that covers Miami-Dade and Broward counties. The statewide Florida Product Approval is a uniform approval accepted across non-zone jurisdictions. Sarasota and Manatee County are not in the High Velocity Hurricane Zone, so products here need either a Florida Product Approval or a Miami-Dade NOA, and you can look either up in the public databases. See the wind zones guide for the local code geography.

The tests behind the label: ASTM E1886 and E1996

An impact rating comes from two linked standards. ASTM E1886 is the test method. A product is hit with a missile, then run through thousands of cycles of positive and negative pressure that mimic sustained hurricane wind pushing and pulling on the glass. ASTM E1996 is the specification that decides which missile and how much energy apply, based on the wind zone and the height of the opening, and it sets the pass criteria. A product that passes both, without the opening being breached, is what earns the impact rating.

Large missile versus small missile

Not all impact tests are equal. The large missile test fires a roughly nine-pound piece of lumber to represent structural debris, and it applies to openings within about thirty feet of the ground, which is most home windows and doors. The small missile test uses small steel balls to represent roof gravel and lighter debris, for higher elevations. On a coastal home, the openings you touch daily are almost always the large-missile kind.

Design pressure, the number that matters most

Design pressure, or DP, is the wind load in pounds per square foot a window or door is built to resist. It accounts for both positive pressure, the inward push of the wind, and negative pressure, the outward suction on the lee side, which is often the bigger threat. Products are structurally tested to one and a half times their DP rating. Coastal Sarasota and Manatee openings generally require a higher DP than inland ones, because the design wind speed is higher near the water. Be cautious of quotes that translate DP into a single mile-per-hour figure; that is a marketing shortcut, not a code-defined equivalence.

How to read a quote

A sound estimate names three things for each opening: the product approval number (NOA or Florida Product Approval), the design pressure rating, and the missile-impact level. With those, you can compare two bids on the actual product rather than the sales pitch, and you can confirm the numbers in the public databases. When you are ready, impact windows and the cost guide cover the rest, and you can get matched with installers who quote at this level of detail.

Frequently asked questions

What is a Miami-Dade NOA?

A Notice of Acceptance is a Miami-Dade County document certifying that a product passed testing for the High Velocity Hurricane Zone. It is the strictest approval in Florida. Sarasota and Manatee County are not in that zone, so they accept products with a statewide Florida Product Approval or a Miami-Dade NOA.

What do ASTM E1886 and E1996 test?

E1886 is the test method: a product is struck by a missile, then subjected to cyclic positive and negative pressure that simulates sustained hurricane wind. E1996 is the specification that sets which missile and energy apply in which wind zone, and the pass criteria. Together they define an impact-rated product.

What is a design pressure or DP rating?

Design pressure is the wind load, in pounds per square foot, a window or door is engineered to resist, accounting for both inward push and outward suction. Products are structurally tested to one and a half times the DP. Coastal openings in Sarasota and Manatee generally need a higher DP than inland ones.

What is the difference between large and small missile?

The large missile test uses a roughly nine-pound piece of lumber to simulate structural debris, and applies to openings closer to the ground. The small missile test uses small steel balls to simulate roof gravel, for higher elevations. The applicable level is set by the wind zone and height under ASTM E1996.

Are impact windows hurricane proof?

No product is. Impact windows are impact-resistant: the outer glass can fracture on a strike while a laminated interlayer holds the pane together and keeps the opening sealed. That controlled cracking is the design, tested to published standards. Treat any absolute claim of storm-proof performance with skepticism.