Positive Drainage

I am trying find the actual code that says the lot of a new construction home must have positive drainage. In other words, if the lot floods and does not drain within a certain amount of time (in this situation it takes weeks), then it was not properly graded. Thanks.

International Residential Code 2006

Ch. 4 Foundations: Section R401.3

R401.3 Drainage

“Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection so as to not create a hazard. Lots shall be graded to drain surface water away from foundation walls. The grade shall fall a minimum of 6 inches (152 mm) within the first 10 feet (3048 mm).”

Exception:Where lot lines, walls, slopes or other physical barriers prohibit 6 inches (152mm) of fall within 10 feet (3048 mm), the final grade shall slope away from the foundation at a minimum slope of 5 percent and the water shall be directed to drains or swales to ensure drainage away from the structure. Swales shall be sloped a minimum of 2 percent when located within 10 feet (3048 mm) of the building foundation. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped a minimum of 2 percent away from the building.


Good info John. Here in Phoenix we have a local standard that takes it a little farther, as do many municipalities. We may be of more help if Unregistered guest would let us know where they live.

Sounds like they are asking about a perc or percolation test.