Minimum Slope For Concrete Slab Drainage

It depends on the application.

Minimum slope for concrete slab 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. The proper slope for runoff drainage is a 1 4 inch of slope per foot of concrete slab. 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. What is a good rule of thumb for the fall or slope on exterior flatwork.

If the slope is more gradual than this you may run into trouble getting water to run off properly. This means the end of a patio protruding 10 feet from a home will drop two and a half inches from the. Section r401 3 impervious surfaces that are within 10 feet of the building s foundation must slope at least 2 away from the foundation. If the slab elevation at the trench.

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. Proper drainage slope based on the international residential code is a minimum fall slope of 6 away from the foundation for the 1st 10. You have to consider the surrounding grades and any nearby structures of course. Aci committee 302 guide for concrete floor and.

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. 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. I ve heard both 1 8 inch per foot and 1 4 inch per foot.

A 2 slope will probably ensure better drainage we could also find no slope tolerance for use when a floor slope is specified. A concrete slab that is 10 feet long should have a slope away from the home of 2 1 2 inches. Set forms so that the concrete slab surface slopes a minimum of two percent or 1 4 inch per foot to provide adequate drainage. When drainage is required on surfaces at facilities covered by the ada the minimum and maximum slope become the same.

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