We purchased a new home in Sacramento California 6 1/2 years ago. We have had a constant issue with our garage floor having an abundant amount of thick white powder substance. Our contractor states this is a normal occurance but everything that sits on the floor of the garage develops mold underneath it and the white powder outlines the shape of the item. I mean any item. Tires, tools, lawn mower, hammer, shoes, hair barrett, etc. Can this be corrected? What is an acceptable amount? Can this be causing an air quality issue? It just seems since we have been in this house, our noses are always clogged like we have colds or allergies. How do I verify that this is an acceptable occurrence? Is this happening throughout the house? etc... Need help or guidance into the right direction! We have also have a small (quarter size) hole develope towards the middle of the garage.