Elevated relative humidity at a surface – 70 percent or higher - can lead to problems with mold, corrosion, decay and other moisture related deterioration. When relative humidity reaches 100 percent, condensation can occur on surfaces leading to a whole host of additional problems. An elevated relative humidity in carpet and within fabrics can lead to dust mite infestation and mildew (mildew is mold growing on fabrics).
Low relative humidity can lead to discomfort, shrinkage of wood floors and wood furniture, cracking of paint on wood trim and static electricity discharges.
The key is not to be too low and not to be too high. High enough to be comfortable, but low enough to avoid moisture problems associated with mold, corrosion, decay, and condensation.....
......Interior relative humidity should be maintained so that a 70 percent relative humidity at a building surface is avoided in order to control mold growth and should never rise above 60 percent in any event.
(Source:
http://www.buildingscience.com/document ... e-humidity )
Manufactured homes do not like moisture, any more or any less than any other framed structure. I am in Central Florida, the humidity capitol of the Western World. I live in a manufactured home and own several MH rentals. Modern high efficiency central air units handle the humidity in our homes and keep the insides very comfortable. All structures in Florida tend to show the effects of the humidity on the outside
Running several dehumidifiers may not be much more energy efficient than turning on the central air but surly wont hurt. Concerns about energy conservation has lead to the development of energy efficient air systems. The key to de-humidification is correctly sizing the air unit to volume of space it needs to manage. Undersizing of air conditioning equipment can lead to to obvious comfort and humidity problems. However, oversizing of air conditioning equipment can also lead to high interior humidity problems since oversized equipment will not operate as often, and therefore will dehumidify less than properly sized equipment.
Air unit size in the humid south is calculated differently than in dryer climates. Consult with an experienced air conditioning contractor to find out what is right for your location.