Impact resistant doors speaks what are impact resistant doors and why use impact resistant doors.
These doors in buildings in hurricane prone regions subject to extremely powerful and destructive winds and glazed openings in such buildings which are especially vulnerable.
The pressure of high speed wind can cause glass to break ot it can suck whole lights out of their sashes, whole sashes out of their surrounding frames or whole frames out of their openings. Glass in doors and elsewhere can be broken by rocks, severed limbs or other debris launched by the wind with missile like force.
Once openings, including doors in buildings are breached the force of the wind can, in extreme cases, blow the roof off of a structure. Even where a building structure remains intact, failed openings can admit large amounts of rainwater that can severely damage the building and its contents.
In the International Building Code doors and glazed openings in doors and windows in wind borne debris regions must meet special standards for resistance to high wind forces and debris impact. These regions include portions of the US and Canadian Atlantic ocean and Gulf of Mexico coasts, the islands of Hawaii and certain other territorial islands that are frequently subject to hurricane force winds.
In these regions, most glazed openings must meet the requirements of two tests, ASTM E1996 and E1886, which subject assemblies to airborne missiles and cyclical air pressures to determine their ability to remain in place under hurricane like conditions. The testing can be quite dramatic.
For windows destined for installed locations not more than 30 feet (0.1 m) above grade, a 9 pound roughly 8 feet long ( 4.1 kg, 2.4 m) 2 X 4 is fired endwise toward the window or door from a special cannon at a speed of 34 mph (55 kph). While the glass is permitted to crack, it must survive in place, without being penetrated by the 2 X 4.
Such impact resistant openings (hurricane rated openings) are fitted with laminated glass with a heavy interlayer of PVB or other similarly tough, viscous plastic. They also have stronger glazing and gasketing systems to better hold their glass units in place, their frames are structurally reinforced and they are fastened into their rough openings with extra strong attachment hardware.
As an alternative to providing impact resistant openings in one and two storey buildings, the code permits the use of precut plywood or OSB panels that can be fastened into place over the outside of such openings when needed to act as temporary storm shutters.