I have a new home -1 year old. This is our first summer in the house (South Carolina) and we began to experience a musty odor in early July. I bought a Rh gage and found humidity level of 75-80% on the first floor of our 2 story home. I also found some light mold on shoes and clothes in the master closet. The closet has an air vent and a ceiling fan already. The house has a 1/2 basement (block), with an approximately 2000 sq. ft. of crawlspace. The crawlspace has a full vapor barrier. A house inspection made Sept. 2003, just after moving in, found the crawlspace wood moisture content at 17-20%. A termite inspection in July 2004 found moisture content at 22-23% and noted some minor standing water due to condensation from A/C ducts.
The house has Trane XR 12, 13 seer units -(1)5 ton for the main floor and (2) 2.5 ton units for the upstairs and basement. There are (2) Aprilaire 5000 electronic air cleaners on the 5 ton unit and an Air Screen 1000 on the upstairs unit. The musty odors seem to be most noticeable in the areas over the crawlspace as opposed to the areas over the basement.

By running two portable de-humidifiers on the 1st floor and 2 in the basement, I have been able to lower the humidity levels to 62-65% and reduce odor somewhat.

Actions I am considering:

Bleaching wood in crawlspace and using fans to dry.

Installing de-humidifiers in crawlspace

Covering vents in crawlspace and adding A/C register

Cleaning of in/out coil/pans

Adding a wholehouse integral de-humidifier and humidistat

A UV light?

I need a sanity check and help finding a qualified pro to get this done. Thanks, B.B.