Hurricane proof building
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Tornadoes, cyclones, and other strong winds damage or destroy many buildings. Here are some architectural design considerations.
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[edit] Storm surge considerations
Beach front buildings must withstand the ocean rising 20 or more feet. They should preferably be built on high ground where possible in order to avoid waves knocking the building down.
If waves can reach the site, the building should be built on steel, concrete, or wooden poles unless it can be anchored to solid rock. To avoid high pressure water waves, the first floor's walls can be made of a layer of sheetrock to allow water (or high winds) to pass through.
[edit] Wind loading considerations
[edit] The foundation
Gravity alone may not be sufficient to prevent building uplift. The upper structure should be securely anchored to the foundation wall. By installing a Hurricane Harness roof protection tie-down system, straps designed to resist elongation and provide superior strength will place the upper portion of the building in a form of compression within itself. That is to say, the roof is pulled down to the walls, and the walls are pulled down to the foundation. The distribution of loads applied by the straps, are passed through the tie-downs, directly to the foundation of the building. Thus the negative uplift pressures generated by the winds passing over the roof,(somewhat like the wing of an airplane) are alleviated by the positive downward pressures exerted by the Hurricane Harness tie-down straps. The system is developed to enhance a building's overall structural design, quickly and effectively days before a hurricane approuches, then taken down after the storm passes. The tie-down system can easily be installed by homeowner's, contractor's, or disaster response organization's such as the Florida Hurricane Ranger's Association. Visit www.hurricaneharness.com for further details on this engineered, "seat belt for the home" hurricane resistant building foundation anchoring system.
[edit] Dome homes
Geodesic dome roofs or buildings made from wood, steel, or concrete have low drag coefficients and can withstand higher wind forces than a square building of the same square footage.
[edit] Earth sheltered buildings
Earth-sheltered home that are above the maximum level of expected storm surge would provide an ideal protection against wind blown debris flying along at up to 150 miles per hour. In addition, the earth shell provides thermal mass that lower daily or seasonal temperature swings.
[edit] Building components
[edit] Roof
Residential buildings with roof trusses should have the roof reinforced and stabilized along the length as well as at the ends. The highest standard meeting code approvals requires metal straps that wrap around the roof trusses or rafters and connect to the top plates of the exterior walls. Since the roof system provides diaphragm action which strenghens and stabliizes the walls and overall building's structural system, the loss of a roof can severely weaken the remaining part of the structure, resulting in catastrophic conditions. Furthermore, the loss of the roof exposes the walls to additional wind loading from within the structure, resulting in complete loss and endangerment to the occupants . Considering the fact that the structure is in a weaken state, once the roof is lost, makes this situation very undesirable for the homeowner. In addition, the interior of the structure is exposed to the elements of excessive water damage from rain accompanied with winds in a hurricane. For the above reasons, structures in high wind zones must be built or retrofitted to minimize the likelihood of having their roof system lift off during high wind storms. Therefore, newer homes must be built following code approved standards, or older homes retroffitted with over the roof strapping systems, anchoring securely the roof structure to the foundation.
[edit] Gable versus hip roofs
Gable roofs are not usually recommended in hurricane areas as these have a larger drag coefficient than a hip roof or dome roof.
[edit] Garages, windows, doors, and other openings
These are generally the weak points susceptible to breakdown by wind pressure and blowing debris. Once inside, wind pressure builds up in seconds and may blow off the roof of building. Hurricane shutters provide an effective protection.
[edit] Doors
Exterior doors should open outward in hurricane prone areas. An inward opening door can be blown into the house by wind causing potential structural failure.
[edit] Garages
When the garage door fails, it is usually the largest opening into the structure. Garage doors have large surface areas and therefore have great amount of force exerted upon them. Various companies offer New doors that adhere to the local building codes. Some companies offer retro-fit devices that can be professional installed. These kits are often just as expensive as a new door. A good source for products include the Miami-Dade building Code website @ www.buildingcodeonline.com and search for approved products. They show how the products are to be installed to withstand the most punishing of winds. Some of the companies are local and many products were in use prior to Hurricane Andrew "The BIG ONE".
[edit] Windows
It is usually a requirement to install 150 mile per hour tested windows in hurricane prone areas. These windows should have plastic panes, shatter-proof glass or glass with protective membranes. The panes have to be more firmly attached than normal window panes (possibly even using screws or bolts through the edges of larger panes). See hurricane shutters.
Windows protected by steel or heavy aluminum shutters may be best in some hurricane prone areas.
[edit] Building materials
[edit] Wood
Termite and dry rot are frequent problems in timber buildings in susceptible areas, particularly in warm, humid area. Weakened buildings cannot withstand high wind loads. According to "This Old House" television show, when wood is used in Key West, building codes require pressure treated wood, which is termite resistant, for all structural elements.
Also, wood and paper backed sheetrock provide food for black mold which can cause added expense to remove the toxic black mold if the inside of the building gets wet during a storm.
[edit] Concrete
Reinforced concrete is a strong, resilient material that can withstand the destructive power of high winds and high-speed debris. While rebar can rust, there are various effective means to retard or prevent rebar corrosion due to moisture.
