Positive drainage The deliberate slope and design of a sidewalk surface that guides rainwater entirely away from building foundations and directs it safely toward street gutters.
Achieving positive drainage is a mandatory requirement for any successful NYC sidewalk installation. When a sidewalk is flat or sloped backward toward a property, rainwater collects against the building's foundation, causing basement leaks, structural erosion, and surface ponding. To establish positive drainage, contractors must grade the sidewalk with a continuous, ADA-compliant downward slope (maximum 2.00% cross slope) leading directly to the curb.
Frequently Asked Questions About Positive drainage
What is positive drainage?
Grading that carries water away from the building and toward the street gutter, rather than letting it pool or run back toward the foundation.
Why does it matter for a building?
Water pushed toward the foundation causes basement leaks, erosion beneath the slab and long-term structural problems.
How is it achieved?
A continuous downward pitch from the building line to the curb, within the 2 percent cross slope limit for accessibility.
What indicates a drainage problem?
Puddles that remain after rain, water stains along the building base, algae growth, and ice patches forming in the same spot each winter.