Minimum Slope Of Concrete Floors For Water Drainage

Typically on straight road sections the drainage gradient is at least 1 3 due to the normal cross slope of 1 3.

Minimum slope of concrete floors for water drainage.

But the reason for including any fall rather than making the surface level is to allow the concrete surface to drain. Generally using 1 8 inch fall which is 1 1 4 inch per 10 feet works well on larger surfaces like driveways and patios but it requires good screed bullfloat and finishing operations to minimize water puddling birdbaths. The preferred slope is between one quarter and one eighth inch per running foot of floor length. Stuff heavy stuff will tend to settle out and not move along as fast as it should jon.

1 8 per foot is minimum you should use. So to calculate the difference in height between one end of a patio or walkway and another simply multiply the length by one quarter. The standard formula for the slope of a concrete patio is a 1 4 inch drop for every foot of length. You need 1 4 inch of slope for every linear feet of floor space.

Positive drainage requires a slope of 1 4 in ft 20 mm m however even at this slope some standing water often called birdbaths should be expected after a rain due to construction tolerances and normal surface deformations over time. A little more won t hurt but too much will. For example a floor that extends 4 feet away from the drain should have 1 inch of overall slope. In curved sections the drainage gradient is higher and may often reach 5 12 due to superelevated cs that may reach 5 8 in areas with icy roads and up to 12 in areas without icy roads.

As a rule of thumb all areas around the drain should have a similar slope. We could find no reference to recommended slopes when trench drains are used in a floor. The only aci document that discusses slope of exterior patio slabs is aci 302 1r 04 1 it states that. If too little slope even if the water drains it won t be self cleaning i e.

The standard slope for proper concrete drainage is a one quarter inch drop for every foot of length. If the slope is more gradual than this you may run into trouble getting water to run off properly. The recommended slope for flat roofs is usually 1 1 8 inch per foot or 2 1 4 inch per foot according to the professional handbook of building construction published by john wiley sons new york.