The home is located in southern Oregon. The additions were attacted to the main foundation. The original foundation left corner was extended out 20 ft. Basically they added a 20x20ft box on the left corner of the house. I don't believe the footings were properly done..?? I can see a crack running from top to bottom were the addition was added to the original foundation. The moisture that is under the house during the winter I believe is due to poor dranage because the the clay the home is sitting on. I have water gutters that drain away from the house as well. Should I place french drains completely around the property line? I need help. Thanks.