Poor Performance The cause behind a drainage system that fails to direct runoff away from the foundation could be one or a combination of several factors, from an improper slope to a downspout to a backfill mix and/or grade slope that doesn’t allow it to flow away from the structure. Check and correct all connections, look for and solve blockages, extend downspouts as far as reasonable, and/or install splash blocks.
Clear the Way The No. 1 cause of gutter and drainage system problems is blockage. Sure, it’s a maintenance issue for the owner, but help them and your warranty department by recognizing and planning for sources of debris that might clog the system. Trim back overhanging trees and install a gutter guard or leaf screen that allows water but not leaves and twigs into the gutters.
Grade Properly Assuming the downspouts and/or splash blocks direct runoff at least 5 feet away from the foundation, grade the property at least 6 inches for the first 10 feet around the house, and another foot over the next 100 feet, as possible or practical. Of course, a sharper slope is better for drainage, if not marketability. The slope can be less on hardscapes, such as non-permeable driveways.