Minimum Slope For Concrete Slab Drainage

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.

Minimum slope for concrete slab drainage.

The standard slope for proper concrete drainage is a one quarter inch drop for every foot of length. A concrete slab that is 10 feet long should have a slope away from the home of 2 1 2 inches. 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. 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.

It depends on the application. The proper slope for runoff drainage is a 1 4 inch of slope per foot of concrete slab. What is a good rule of thumb for the fall or slope on exterior flatwork. If the slab elevation at the trench.

This means the end of a patio protruding 10 feet from a home will drop two and a half inches from the. You have to consider the surrounding grades and any nearby structures of course. If the slope is more gradual than this you may run into trouble getting water to run off properly. A 2 slope will probably ensure better drainage we could also find no slope tolerance for use when a floor slope is specified.

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. Section r401 3 impervious surfaces that are within 10 feet of the building s foundation must slope at least 2 away from the foundation. Set forms so that the concrete slab surface slopes a minimum of two percent or 1 4 inch per foot to provide adequate drainage.

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. 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. 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.

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. Proper drainage slope based on the international residential code is a minimum fall slope of 6 away from the foundation for the 1st 10.