The minimum positive site drainage is a drop of six inches in the first ten feet.

A clay "cap" under any topsoil is the ideal material next to the foundation.

But before you start any such major work, check the obvious--which is not so obvious to many property owners: functioning eavestroughs and downspouts that divert the water far from the foundation wall, at least 4-12" ins between the soil and masonry or siding, limited or no foundation plantings.

Three things � 1. Make sure your downspouts and gutters are in good working order, (overflowing gutters and poorly directed downspouts are major culprits in basement water intrusion). 2. Make sure you landscaping slopes away from your home, (there is no set sloping degrees however the more slope and the farther from the house the better). 3.Use as little decretive mulch & gravel as possible, (both hold water and contribute to basement water intrusion so in this case, less is better).