Fill dirt used for corrective grading around foundation where original backfill settled. 1 Inadequate Drainage The backfill in the overdig area around foundation walls inevitably settles. This creates a negative grade toward the foundation. Downspouts that empty roof drainage into this area (something splash blocks won't prevent) increase ground saturation. This results in the hydrostatic pressure that creates damp basements and wet crawlspaces. Build foundations high enough to establish a more pronounced grade away from the house, and extend downspouts with leader pipes to deliver water past the overdig area. The gravel beds beneath sidewalks and driveways are often traps for yard runoff water. This leads to settlement and slab cracking in all climates, and frost heaving where it's cold. Knowing where surface water
