Report Urges Implementation of Mobile Home Tornado Standards

Written by Cory Chandler

News Release

DATE: June 2, 2006
CONTACT: Cory Chandler,
(806) 742-2136

Researchers Call upon Governments to Beef up Standards after Indiana Tornado

LUBBOCK, TEXAS – After determining that faulty anchoring was a major contributor to devastation by a November tornado to an Indiana mobile home park, a Texas Tech University wind engineer is urging governments to adopt and implement in-depth construction standards and beef up manufactured housing inspection.

In a report for the National Institute of Standards and Technology, Larry Tanner, a civil engineering research associate and member of the university’s Wind Science and Engineering Research Center, called upon state, county and municipal governments to “adopt, implement, and inspect to ensure a strict compliance” with installation standards laid out in the National Fire Protection Association’s Form 225, Mobile Home Installation Standard 2005 Edition. The association is one of two entities given the task of overseeing construction and installation of manufactured homes.

Their findings indicate that manufactured housing constructed with full wood sheathing and properly anchored can reasonably resist the minimum wind speeds to which they are designed – approximately 90 mph; however, improvements in construction methods and tie-down connections are needed. The anchoring systems are vital in keeping the structures from flipping over or being blown off supports during disasters such as tornadoes or hurricanes.

The report found that guidelines prescribed by Housing and Urban Development, the federal agency with oversight of mobile home manufacturing, are “non-prescriptive and general.” These are the primary guidance for manufactured housing construction, the report says.

“While information regarding the wind resistant design of mobile home tie-downs is discussed in the (American National Standards Institute) and HUD standards, nowhere in the standards are there found specifications governing the installation and the inspection of manufactured housing anchors,” the report noted.

Recognizing this loophole in the standards, Congress passed the National
Manufactured Housing Improvement Act of 2000 requiring each state to develop a manufactured housing installation program in order to provide oversight and enforcement. This led to an update of the NFPA’s 225, Model Manufactured Home Installation Standard, 2005 Edition to provide specific information on site preparation, determination of soil bearing capacity, foundation design, support piers, and anchoring guidelines. It also prescribed the maximum anchor spacing.

“The general consensus has long been that a mobile home can be a nice place to live, but that it’s just not going to be safe in severe windstorms,” Tanner said. “Through our investigations, we discovered that by making these few changes – and they are not necessarily small changes, but they are not insurmountable – a mobile home owner could safely ride out a 50-60 mile wind storm.”

Tanner added that the report is not intended as an indictment, but simply a statement of facts the researchers have gathered with recommendations.

Working with James Waller, a Tennessee structural engineer and president of RemagenSafeRooms, Tanner investigated damages caused by the November 6 tornado, which killed 22 people in Evansville, Ind. While the two men studied the entire path of the tornado, their investigation focused on the Eastbrook Mobile Home Park, where 18 people died and 110 homes were damaged.

The engineers, utilizing a uniform damage scale, surveyed all units within the park for damage and randomly sampled 1/3 of the units specifically for installation performance. They stated that manufactured homes fail during wind storms for three reasons: high pressures as air flows over and around a structure; impacts from flying debris or missiles such as sheet metal or vehicles from upwind locations; and atmospheric pressure change, sometimes referred as the “explosive effect,” which is unique to tornadoes.

A preliminary report released in November prompted officials in Evansville and Vanderburgh County to adopt tougher installation standards and ask Indiana Gov. Mitch Daniels to strengthen state requirements on anchoring and bracing new mobile homes.

The report can be found here:


CONTACT: Larry Tanner, research associate, Department of Civil Engineering and Wind Science and Engineering Research Center, Texas Tech University, at (806) 885-2333, ext. 226, (806) 742-3476 ext. 336, or