Minimum Slope For Concrete Slab Drainage

A concrete slab that is 10 feet long should have a slope away from the home of 2 1 2 inches.

Minimum slope for concrete slab drainage.

If physical barriers such as walls slopes or the lot lines limit the ability to achieve 6 inches of slope within 10 feet of the foundation than drainage can be achieved by installing drains or swales. Section r401 3 impervious surfaces that are within 10 feet of the building s foundation must slope at least 2 away from the foundation. Aci 117 90 standard specifications for tolerances for concrete construction and materials gives a level alignment tolerance of 3 4 inch for top of slab elevation of slabs on grade. Set forms so that the concrete slab surface slopes a minimum of two percent or 1 4 inch per foot to provide adequate drainage.

Slopes that are steeper than this are fine but you may also wish to consider the ease of mobility on a concrete patio that is too steep. The standard slope for proper concrete drainage is a one quarter inch drop for every foot of length. This means the end of a patio protruding 10 feet from a home will drop two and a half inches from the. If providing adequate drainage is a problem because of other building structures surrounding the concrete slab you may wish to consider the addition of a drain on.

When drainage is required on surfaces at facilities covered by the ada the minimum and maximum slope become the same. The proper slope for runoff drainage is a 1 4 inch of slope per foot of concrete slab. It depends on the application. A 2 slope will probably ensure better drainage we could also find no slope tolerance for use when a floor slope is specified.

Proper clearance above grade to the top of foundation bottom of exterior cladding is a minimum 4 for masonry areas with a minimum 6 clearance above grade at siding areas. If the slab elevation at the trench. Aci committee 302 guide for concrete floor and. So to calculate the difference in height between one end of a patio or walkway and another simply multiply the length by one quarter.

I ve heard both 1 8 inch per foot and 1 4 inch per foot. Walk in any direction on a patio slab 1 48 1 4 in ft would also appear to be the maximum allowable slope for the slab in question which presents a dilemma. If the slope is more gradual than this you may run into trouble getting water to run off properly. You have to consider the surrounding grades and any nearby structures of course.

The standard formula for the slope of a concrete patio is a 1 4 inch drop for every foot of length. But the reason for including any fall rather than making the surface level is to allow the concrete surface to drain.