Large-missile impact test
Also called: missile impact test, ASTM E1996, TAS 201, large missile level D, impact rating, cyclic pressure test
The test that makes a window an impact window: a 9 lb 2×4 fired at the glass at about 34 mph, twice, followed by 9,000 cycles of positive and negative pressure. The glass may crack but nothing may pass through and the frame must hold. Defined in ASTM E1886/E1996 and Miami-Dade TAS 201–203.
After Hurricane Andrew in 1992, South Florida wrote the test that the rest of the coast adopted: if a window is going to protect a house, it has to survive being hit by debris and then hold through hours of gusting wind. The large-missile test does both. A 2×4 weighing about 9 lb is launched from an air cannon at 50 ft per second (34 mph) into the center of the glass and then into a corner. The laminated glass is allowed to crack — the plastic interlayer holds the pieces — but no opening larger than a few inches may form and the frame, glazing and anchors must stay in place. The unit then goes into a chamber and is cycled through 4,500 positive and 4,500 negative pressure pulses at fractions of its design pressure, simulating a storm’s gusts, without failing.
Levels vary. ASTM E1996 defines missile levels A through E; residential impact windows in wind zones are typically Level D (the 9 lb 2×4). Miami-Dade’s TAS 201, 202 and 203 are the stricter High-Velocity Hurricane Zone version, and products that pass earn a Miami-Dade Notice of Acceptance. Small-missile tests (steel balls at higher speed) apply to openings above 30 ft.
The result is what “impact-rated” means on a label, and it’s independent of the design pressure rating: a window has both, and an opening needs both to be right. Shutters are tested to the same missile standard, which is why either qualifies for the insurance credit.