If the ground is wet, the first order of business is to try to seal it off. Someone should have spread heavy plastic under the enire home. You can still do it should help somewhat. Also, do you have ventilation in your skirting? That would also help.
Be reminded that much of the moisture found might be generated within the home. Is your dryer vented out side the skirting? Do you run humidifiers? Do you hang clothes to dry inside the home? Do you have exhaust fans in your bathroom that are vented to the outdoors? Are you in the habit of simmering food on the stove for hours at a time? Just some suggestions of how moisture can build up from the inside. Good luck.

The ground isn't seal with heavy plastic. If I do so isn't the plastic going to get wet and mildew will form?Dryer is vented out and I don't dry clothes inside my home, no vent in bathroom and I cook a lot, but that doesn't explain why I have only wet ground at certain area of the house only and not the entire ground. I should put a fan ventilation underneath my house.
Thanks

Philippe

If you use a heavy plastic this will act as a vapor barrier. The moisture will stay below the plastic and this is what you want. Plastic is available in different sizes. We used to get it in 100 foot long rolls and used it under every mobile home that we installed if the home was not on a concrete slab.
If you seem to be getting more moisture in one room, I would be sure to check that water is not somehow getting into that room. Could you have a roof leak that is getting into the walls of that bad area?
Is there a plastic barrier with insulation that is attached to the underside of the home? Most of the mobile homes came with this. If this is missing or torn, moisture will get in through this opening.
I once saw a home with this plastic installed as it shoud be. A pipe leaked under the home and the wate became trapped up inside this plastic. Since the water just sat there, a lot of moisture developed in the home. If you crawl under the home, check to see if there is a big bulge anywhere in the plastic. If there is, check to see if it feels like there is water in there. If so, it could be a leaky pipe.
While you are under the home, also check to see if the plastic and insulation is torn in any place. If it is, you might be able to repair it with duct tape.
Hope this helps.
Mark

you are going to have to use mastik tape it is only sold at mobile home supply stores. it is what they use when they build them and it is sticky and it do cost plenty. $15.00 a roll.