Most people do not realize that there is even a code for the clearance from the ground to wood sheathing and sidings.  Over the years, we have received calls from our customers stating that water is coming into the building under a wall, or the bottom of the siding is deteriorating.  Upon our inspection, landscaping was done following the completion of the building, placing dirt/sod right up to the bottom of, or even over, the siding causing the water related issue.  The code states there must be a 6” clearance from the top of the finished grade to the bottom of wood siding or sheathing.  This ensures there is ample room for air to dry the most susceptible part of the building.