Slope For Concrete Slab Drainage

The patio needs to have a uniform surface to lay on.

Slope for concrete slab drainage.

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. If the slope is more gradual than this you may run into trouble getting water to run off properly. You need to remove any vegetation soft soil and rocks before you begin. So to calculate the difference in height between one end of a patio or walkway and another simply multiply the length by one quarter.

Use a scratch template typically a piece of 2 by 4 or 2 by 6 lumber equal to the specified slab thickness with stakes attached to the top surface at each end or a string line across the top of the forms to ensure proper slab thickness. If the slab elevation at the trench drain is within 3 4 inch of the plan elevation and the slab top elevation farthest from the drain is also within 3 4 inch of plan elevation the slab. The recommended slope is 1 4 inch per foot but it can be anywhere from 1 8 inch to 3 8 inch per foot depending on other factors. The proper slope for runoff drainage is a 1 4 inch of slope per foot of concrete slab.

A concrete slab that is 10 feet long should have a slope away from the home of 2 1 2 inches. Calculate the ideal slope the standard formula for the slope of a concrete patio is a 1 4 inch drop for every foot of length. Set forms so that the concrete slab surface slopes a minimum of two percent or 1 4 inch per foot to provide adequate drainage. 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.

Slope the sand 1 inch for every 20 feet. Pour the sand into the trench sloping it toward the area you want the water to drain to don t drain it toward the house. The only aci document that discusses slope of exterior patio slabs is aci 302 1r 04 1it states that. A 2 slope will probably ensure better drainage we could also find no slope tolerance for use when a floor slope is specified.