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Hurricane coverings, commonly known as shutters, are used in hurricane mitigation to protect houses and other structures from damage caused by storms. Hurricane shutters are used to prevent windows from being broken by flying objects during a storm. Although the negative pressure caused by high velocity wind flowing over a building roof can cause the roof to fail with the building envelope intact, broken windows allow the air pressure to rise inside a building, creating an even greater pressure difference, and increasing the likelihood of roof failure. Shutters are frequently constructed from steel or aluminium, but homeowners sometimes use the low-cost alternative of plywood. The shutters are affixed to the outside of the building with screws, hurricane clips, or a track system. Advanced shutters may be motorized, and they may fold away when not in use. ==Types of hurricane coverings== Three major types of shutters are known alternatively as panel systems. They are usually made of plywood, metal (aluminium or steel), or polycarbonate plastic. Lexan panels are transparent, and may be flat or have been heat-formed into a corrugated shape to further increase impact resistance. Panels must be attached to the structure via screws in a direct mount or on tracks. When not in use, storm panels are stored in an easy to reach location. Newly constructed homes sometimes have an assigned area for storage of storm panels. Another type of shutter is an accordion shutter which are made from interlocking vertical blades which slide into place horizontally on a track. They are operated by pulling each curtain toward the center of the track, latching the curtains together and locking the handle. Another type is the roll-up or rolling shutter, consisting of a series of slats that form a curtain with both sides of the curtain being inserted into guide rails. The curtain is then rolled onto an axle which is covered by a housing. Rolling shutters can be operated manually by gear, by pull strap or can be motorized independently or in conjunction with a manual override. Motorized shutters can be operated by either a switch or remote and can be controlled either individually or in groups. On loss of power caused by hurricanes, motorized shutters must be operated manually, requiring either access to the motor (which can be difficult) or a pre-installed manual override. Most often, a manual override is operated using a gear. When deployed, all hurricane shutters require special techniques for firefighters to gain access to the interior of a structure. Other types are the Bahamas and Colonials. Bahama shutters are mounted above the window creating shade when they are open, and when in use, they are brought down and secured over the window. Colonials are similar to the wooden shutters, but are made of aluminum. They hinge on the side of the windows and swing shut to protect the opening. Also used are awning shutters, with a horizontal hinge above the opening being protected. Hurricane fabric coverings are a newer, relatively lower cost type of shutter. Tested and approved systems are made from polypropylene fibers, polyamide fibers or from laminated or cast PVC. In 2011, a flat hurricane shutter system developed by UltraTek Worldwide was approved by Florida Building Code.〔ClearTek Approval from http://www.floridabuilding.org/upload/PR_Instl_Docs/FL14078_R0_II_INSTALLATION%20INSTRUCTIONS%2010-09020A.pdf〕 The unique system uses a synthetic rubber bracket to absorb hurricane forces, allowing a panel that is completely clear while weighing 11.3 oz/square foot, nearly half the weight of a traditional metal panel.〔Going Flat Out from http://catalog.proemags.com/publication/053f23e7#/053f23e7/18〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hurricane shutter」の詳細全文を読む スポンサード リンク
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