How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
How much hurricane wind speed can a mobile home survive?
Tuesday, June 19, 2018
Four variables affect how a mobile home will fare in a hurricane: 1) when it was built, 2) the wind zone it was designed for, 3) how well it has been maintained, and 4) what additions have been made to the home and how they are attached.
1 - WHEN THE HOME WAS BUILT
There are four eras of mobile construction standards, each one progressively more hurricane-resistant than the previous era. Homes built before July, 1976, which was when HUD took over making and enforcing new “HUD Code” standards, are the most vulnerable to wind damage. Although there was voluntary compliance to manufacturer association guidelines and some states had minimal codes for mobile home construction and tie-down, the strength of the pre-1976 structures varied over a wide range and none met later HUD standards.
Hurricane Andrew hit South Florida in 1992 and it was hailed as a “wake-up call” for HUD to improve structural wind resistance of mobile homes, which they did in July, 1994. Then, in 1999, the State of Florida raised the bar on tie-down requirements. HUD followed up by raising the tie-down standards to a nationwide in 2009.
So pre-1976, 1976 to 1994, 1994 to 1999, and after 1999, are each timespans that produced progressively sturdier mobile homes. See our blog post What year were mobile homes required to become more storm resistant? to learn more.
2 - WIND ZONE RATING
HUD requires that manufactured homes be built to one of three wind zone standards. Wind Zone 1 is for areas not considered prone to hurricanes, and no part of Florida is in Zone 1. The upper 2/3 of our state is in Wind Zone 2, designed to tolerate 100 mph winds, and the bottom portion is Wind Zone 3, rated for 110 mph winds.
There is also a special category for manufactured homes to be sited within 1500 feet of the coastline in a hurricane zone. It’s called a “D-sticker” home, and means that it has been designed to meet the wind resistance requirement of ASCE 7-88, Exposure D—which is a standard referenced in the HUD Code.
You can find your mobile home’s wind zone rating on its data plate, which is usually located on the master bedroom wall, on the inside of a kitchen cabinet door, or at the electric panel.
3 - MAINTENANCE
A roof with loose shingles that is at the end of its lifespan, tie-downs that are no longer snug, or piers that have settled and need to be shimmed are all examples of lack of maintenance that will cause you grief during a hurricane.
4 - ADDITIONS
Studies of damage following recent hurricanes has found that home additions—and specifically aluminum carports and screen porches—that are attached directly to the edge of a roof of the mobile home for support will cause failure of the mobile roof when the high winds sweep them away and they peel off the roof at the connection point too. Any addition to a mobile home needs to be structurally self-supporting and built to the standards of the Florida Building Code, with a permit and inspection by the local building department, to avoid jeopardizing the the storm-worthiness of your mobile home.
In summary, a newer mobile home and one rated for a higher wind zone number will stand a better chance of resisting hurricane damage, while lax maintenance and any home additions bearing on the roof or walls will reduce the home’s chances of surviving a hurricane intact at the wind speed for which it is rated.
Mobile home manufacturers like to say that their products are now built to the same wind-resistance standards as site-built homes, but when the local government recommends evacuation of mobile homes in the face of an oncoming hurricane, JUST DO IT. We are dealing with larger and stronger storms recently than many homes, both site-built and mobile, were designed to tolerate.
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Here’s links to a collection of our blog posts about HURRICANE RESISTANCE:
Photo - Hurricane Irma approaching Florida, NASA
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