Suspect that the single line crack across the middle of our concrete 8' x 9' patio is due to soil erosion from the gutter drain. We also suspect the soil erosion is causing the 6' long stone ledge at the base of our sliding patio door to sag. This sagging ledge is causing the patio door to pull away from the floor and wall leaving a 1/4" gap at the base. What to repair first? Are we correct in assuming that much of landscaping to correct soil erosion should occur after the concrete patio & the cracked patio door are replaced? Is completely replacing the concrete patio the only option? What can we do and what must we hire a contractor(s) to do? Is it sufficient to patch the cracks and focus on the soil erosion or should we replace the concrete patio? Should we replace the patio door?