How to Redirect Rainwater Away from Your Foundation

Water is the greatest enemy of a solid foundation, slowly eroding the soil and eventually finding its way into your crawlspace or basement. Managing roof runoff is the most effective way to keep your home's perimeter dry and structurally sound. When your gutters dump water directly against the siding, you are essentially inviting settlement, cracks, and moisture issues that are far costlier than a few lengths of pipe. Done well, your drainage system should be invisible to the eye but obvious in its function. You want a consistent, gradual slope that carries water away from the wall and toward a lower point in the yard or a storm drain. Once you stop the localized flooding at the foundation, you'll notice the basement smells less musty and the soil around your house stops shifting during heavy storms.

  1. Find Where Water Flows. Walk the perimeter of your house during a light rain to see exactly where the water exits your downspouts. Identify areas where water pools against the siding or foundation wall.
  2. Clear Every Blockage. Clean out all leaves, pine needles, and shingle grit from your gutters. Ensure the downspouts are free of debris so water flows freely to the discharge point.
  3. Secure Extensions Firmly. Attach flexible or rigid downspout extensions to the base of each downspout. Secure them with sheet metal screws to ensure they do not detach during high winds.
  4. Build Positive Slope. Ensure the ground surface immediately adjacent to the foundation has a positive slope, dropping at least six inches over the first ten feet. Use topsoil to build up the earth if it currently slopes toward the house.
  5. Install Final Deflectors. Place concrete or plastic splash blocks at the end of each extension to prevent the water from carving a trench in your lawn. Ensure the block directs water away from the house.
  6. Test the Full Flow. Run your garden hose at the top of the gutter again to verify the water travels all the way to the end of the new extension without leaking. Confirm it flows well away from the foundation wall.