Chinese Drywall

"Chinese Drywall," also called odorous gypsum wallboard, has been an issue in new and remodeled homes in Florida, Louisiana, and Texas. The drywall has been determined to emit chemicals that cause sulfide odors, black discoloration of metal fixtures, electrical components, and domestic water piping, as well as corrosion of HVAC components leading to failure. There are also reports of health effects associated with the drywall.

Moisture in crawl spaces

If you have condensation on the ductwork and floor joists in your home's crawl space, usually outside air is the source of the moisture. It is often better to close foundation vents in the summer. Make sure that groundwater is not draining into the crawl space and there is plastic sheeting (vapor barrier) greater than 6-mil over the earth to prevent soil moisture from evaporating into the crawl space.