Manufactured homes are particularly vulnerable to the destructive force of strong winds and tornadoes. Manufactured homes seem to attract tornadoes.
Hurricane Andrew struck the southern tip of Florida and the Gulf Coast regions of Louisiana in late August 1992 with devastating winds in excess of 150 miles-per-hour. The third strongest hurricane ever to strike the United States, Andrew was designated a Category 4. Thousands of homes, both site built and manufactured, suffered extensive damage and destruction from the force of the storm.
Within weeks of the storm, the manufactured housing industry endorsed appropriate improvements in the wind resistance/safety of manufactured homes. After many months of effort by the industry to negotiate proper improvements, the Department of Housing and Urban Development (HUD) issued revisions to the wind safety provisions of the HUD Code, which became effective July 13, 1994.
In areas prone to hurricane-force winds (known as Wind Zones II and III, according to HUD's new Basic Wind Zone Map) the wind safety standards require that manufactured homes be resistant to winds up to 100 miles-per-hour in Wind Zone II and 110 miles-per-hour in Wind Zone III. In both of these zones, the standard for manufactured homes is now more stringent than the current regional and national building codes for site-built homes located in these wind zones.
An important element in the adequate wind safety of a manufactured home is the proper installation and anchoring of the home according to the manufacturer's instructions. Installation standards are regulated on a state-by-state basis. When properly installed and anchored, the manufactured home's wind resistance is significantly improved. For each new manufactured home sold, the manufacturer must include installation instructions to properly support and anchor the home. This requirement is part of the wind storm protection provisions of the HUD Code.
There is no meteorological or scientific basis to thinking that manufactured homes attract tornadoes. The reality is one of coincidence: most manufactured homes are located in rural and suburban locations, where meteorological conditions favor the creation of tornadoes.
A tornado's deadly force does not selectively discriminate between the site-built and manufactured home or "mobile home" (those built prior to the HUD Code's implementation in 1976.)
In most of the country (non-hurricane-prone areas), manufactured homes are built to withstand sustained winds in the range of 70 miles-per-hour. Above this range, a manufactured home will experience some form of damage. Only in the case of severe weather, such as a tornado, are these areas likely to experience winds in excess of 70 miles-per-hour.
It is estimated that approximately 40 percent of all tornadoes have winds in excess of 112 miles-per-hour. Tornadoes can have winds in excess of 200 miles-per-hour in extreme cases. Current building codes and practices, for either manufactured homes or site-built homes, are not designed to withstand winds in excess of 110 miles-per-hour.
A direct hit from a tornado will bring about severe damage or destruction of any home in its path. A tornado's deadly force does not selectively discriminate between the site-built and manufactured home or "mobile homes" (those built prior to the HUD Code's implementation in 1976).
If a manufactured home has a below-ground basement, the home's residents should seek shelter there. If a home, site-built or manufactured, does not have a below-ground basement, the residents should seek immediate below-ground or other appropriate shelter from the storm's possible effects. During a tornado warning, a tornado has been detected. Residents should seek shelter in an interior room with no windows.