Splash Block & Extension Calculator

How It Works

Water pooling near your foundation is the #1 cause of basement leaks, crawl space moisture, and foundation cracking. The minimum rule: direct downspout water at least 4-6 feet from the foundation. With clay soil or poor grading, aim for 8-10 feet. Splash blocks are the simplest solution — concrete or plastic ramps that deflect water outward. Rigid or flexible extensions add 4-8 feet of distance. For serious drainage issues, underground PVC pipes connected to pop-up emitters 10+ feet away are the gold standard. The most important fix for any foundation water issue is proper grading: the ground should drop 6 inches within the first 10 feet from your house.