Buying decisions · 6 min read
Types of impact windows: a plain-English guide for Florida homeowners
The main types of impact windows sold in Florida — single-hung, double-hung, casement, sliding, fixed, and architectural shapes — plus the glass and frame options that actually change price and performance.
What is an impact window, in plain English?
An impact window is a window built around laminated safety glass — two panes bonded to a clear inner layer of PVB or SGP plastic — set into a reinforced frame that's been tested to stay in the opening when hit by wind-borne debris. In Florida, the relevant tests are large missile impact (a 2x4 fired at the glass) and cyclic pressure cycles that simulate hurricane wind. A window only qualifies as 'impact' if the entire assembly — glass, frame, and anchors — passes those tests and carries a Florida Product Approval or a Miami-Dade NOA. Tinted glass alone is not impact. Hurricane film over a standard window is not impact. The lamination plus the tested frame is what makes it impact.
The main types of impact windows by operation
Single-hung: only the bottom sash moves. Most common, lowest cost, fewest moving parts to fail. Double-hung: both sashes move, easier to clean from inside. Modest price premium. Casement: cranks outward on a hinge. Best air seal, common on newer Florida homes. Sliding (horizontal roller): two or three panels that slide horizontally — common on lanais, patios, and Florida room walls. Fixed (picture): doesn't open. Cheapest per square foot and the strongest in wind because nothing has to move. Architectural shapes: arches, half-rounds, octagons, transoms. Custom-quoted, longer lead times, and meaningful premiums — often the budget surprise on whole-house replacements.
What about the glass itself?
Two real choices. PVB (polyvinyl butyral) is the standard laminate interlayer — strong enough for Florida code, used in the vast majority of residential impact windows. SGP (SentryGlas Plus) is a stiffer, clearer interlayer that performs better in high-wind zones and in larger spans; it costs more and is most often spec'd in HVHZ Miami-Dade and Broward on big openings. Beyond the laminate, you'll choose a Low-E coating (almost always worth it in Florida — cuts solar heat gain meaningfully) and optional argon gas fill between panes. None of those change the impact rating — they change comfort and energy bills.
What about the frame?
Three common materials. Aluminum: strong, thin sightlines, the historic Florida default; conducts heat, so look for thermally broken aluminum if energy matters. Vinyl: better insulator than aluminum, holds up well in inland Florida, can warp on west-facing elevations with extreme heat. Composite / fiberglass: best thermal performance, premium pricing, longest expected service life — common on new construction in master-planned communities. The frame matters as much as the glass for both the impact rating and the energy bill.
Which types of impact windows are most common in Florida by region?
South Florida (Miami-Dade, Broward, Palm Beach HVHZ): aluminum-framed single-hung and fixed windows dominate, often with SGP laminate on large openings. Southwest Florida: post-Ian rebuilds lean heavily on aluminum and composite frames sized for the wider openings common in 1990s–2000s stock. Central Florida and Tampa Bay: vinyl and composite frames are increasingly common because the wind loads are lower than HVHZ and the energy savings matter more on summer-long AC bills. Coastal Tampa Bay and the barrier islands often spec aluminum with marine-grade hardware regardless of frame trend — see our South Tampa bungalow guide for the framing-depth complication on older homes.
What drives the price difference between types?
Per square foot, roughly cheapest to most expensive: fixed picture < single-hung < double-hung ≈ slider < casement < architectural shapes. Across the whole house, the bigger movers are total opening square footage, frame material, glass package (PVB vs SGP, Low-E, argon), and whether the project triggers stucco, drywall, or interior trim repair. Two homes with the same number of windows can quote 40% apart based on those choices alone. Our impact windows vs. shutters comparison walks through whole-house budget framing.
How do impact windows compare to shutters?
Impact windows are permanent, require zero deployment, deliver continuous UV/sound/security benefits, and earn the largest opening-protection credit on the OIR-B1-1802 wind mitigation form. Shutters are cheaper up front, require deployment before each storm, and earn a credit only when they cover every opening. For a deeper comparison, see impact windows vs. shutters and the wind mitigation credits guide.
When you're ready to get quotes
The single biggest determinant of a good impact window project isn't the brand on the sticker — it's the installer's experience with your home's era, your region's permitting, and the specific frame system being quoted. See vetted Florida contractors who routinely install impact windows in your region.