I own a 52 yr old house with a bit of a mold problem. Part of the problem is that the walls of the basement are frequently moist - you can see the stains, although they never really feel damp to the touch. The earth around the house is clearly holding water but never hold any pools of water. I dont think that a french drain is the solution. Is there a better way to treat the walls? I have thought about constructing a trench filled with gravel over a drain. Would this help?