Impact window

One Florida form spells opening protection out level by level: the Florida Office of Insurance Regulation's Uniform Mitigation Verification Inspection Form, OIR-B1-1802 (Rev. 04/26).

Its item 9, Opening Protection, asks for “the WEAKEST form of wind-borne debris protection” installed on the structure, a category the form says includes all openings in the wall and roof, windows, doors, sliding glass doors, skylights and garage doors, and does not include gable and other roof vents. The form's Level A answer, cyclic pressure and a 9-lb. large missile, 4.5 lb. for skylights only, is that all glazed openings are protected, at a minimum, with “impact resistant coverings or products” listed as wind borne debris protection devices in the product approval system of the State of Florida or Miami-Dade County, and that they meet one of the standards the form lists for cyclic pressure and large missile impact.

The form also limits its own reach: its definitions “are for inspection purposes only” and “cannot be used to certify” any product or construction feature “as offering protection from hurricanes,” it keeps a separate level for opening protection products that appear to be A or B but “are not verified,” and it requires any documentation used to validate a feature to accompany the form.

An older state fact sheet explains what the testing covers. The Florida Department of Community Affairs' sheet on window systems, which says it is applicable to the 2004 Florida Building Code, says that when an impact-resistant window is tested it is tested “as a unit” with its glass, frame, attachment hardware and installation method, and that products designed to protect a home's openings must be “both tested and approved” for wind load and wind-borne debris.

The glass is one part of the tested unit, and the Florida Department of Community Affairs, in its window-systems sheet for the 2004 code, is careful about which glass.

Impact-resistant glazing, the sheet says, “is available as laminated glass,” and tempered glass windows and impact-resistant windows “are not the same.” PGT writes of its WinGuard line: “Our hurricane windows and doors are made with laminated glass.” The glass itself, plastic interlayer and all, is defined under laminated glass; heat treatment is a separate property, with its own entry at tempered glass. A pane of laminated glass does not, on its own, make an impact-rated window: the testing covers the whole unit.

Whether a particular window carries an impact rating is a question for its records rather than its looks: the maker's documentation, the product's label, its listing in Florida's product approval system or a Miami-Dade County notice of acceptance, and the installer who put it in. A logo on the pane is weaker evidence: the National Glass Association says one may show whether glass is tempered, heat-strengthened or laminated but “typically will not indicate the glass type,” and either way it marks the glass, not the tested unit.

Where a house must have impact protection is for the local building official to say, the office the DCA sheet itself sends readers to. Cleaning rules follow the glass rather than the rating: how the published glass routine applies to impact glass is taken up at whether impact windows can be cleaned like regular windows, and the order of a roof wash and the windows below it is answered in whether the roof is cleaned before or after the windows.