When purchasing and installing a new Manufactured Home, there are two upgrades that are recommended. They are installing a Vapor Barrier and Earthquake Bracing. Each is explained here:
Mobile Home Vapor Barrier
A Vapor Barrier for a Mobile or Manufactured home is a sheet of thick, rubbery plastic that goes directly over the dirt under a Mobile or Manufactured home. The foundation piers then rest on top of this barrier.
You really need to make sure a home you buy or have installed has this protection. Mobile and Manufactured homes need dry ventilation underneath. This barrier will prevent any moisture from damaging the home – especially rotting of the floors, but also helping with fungus, mold, and termites.
Making sure that a vapor barrier is installed before you buy a Mobile or Manufactured home is absolutely necessary. And the additional cost is very minimal considering the amount of protection you gain.
If you are buying a mobile or manufactured home that is already on a space, but with no vapor barrier, then you can hire a contractor to install a vapor barrier under the home. They will just have to cut pieces that will go around the pier-and-post foundation and all piping in place. This is not ideal, but way better than no barrier at all.
Mobile Home Earthquake Bracing
Earthquake bracing is recommended in California, and elsewhere earthquakes are common. Mobile Homes and Manufactured Homes are especially susceptible to damage in a earthquake due to their foundation system (most of the time they are installed on a pier-and-post system).
Earthquake bracing is a simple upgrade that can increase the value of your home by at least the cost of installation of the bracing. This cost is running from $2000 to $4500 in California right now. The actual brace is like a shock absorber in a car, but installed at an angle from the steel I-beam on the bottom of the home, and anchored to the ground. This brace will keep the home from shifting off the pier-and-post foundation.
Insurance companies may insist on having earthquake bracing installed if you want to purchase earthquake insurance on your Mobile Home or Manufactured Home.
Earthquake bracing can also help a Mobile Home not come off the foundation in high winds, although it is not designed to do this and should not be relied on for this.
Pictures and further explanation on both of these upgrades, as well as a whole bunch of free information, tips, advice, and recommendations can be found at: http://www.free-mobile-home-info.com