Question: I want to add some landscaping to the side of my house. I have a slab foundation and would like to know how close to the bottom of the siding I can raise the finish grade of the mulch.
Answer: There should be 8 inches from the top of the finish slab down to the top of the finish grade. Generally, the siding is 1.5 to 2 inches below the finish of the slab so the siding should be about 6 to 7 inches above the finish grade. The finish grade should slope away from the foundation so it can carry any excess moisture away from the foundation. If the finish grade is any higher it can cause mildew, mold, insect and moisture problems for the exterior walls.