Minimum Slope Of Concrete Floors For Water Drainage

A little more won t hurt but too much will.

Minimum slope of concrete floors for water drainage.

As a rule of thumb all areas around the drain should have a similar slope. Typically on straight road sections the drainage gradient is at least 1 3 due to the normal cross slope of 1 3. The standard formula for the slope of a concrete patio is a 1 4 inch drop for every foot of length. Stuff heavy stuff will tend to settle out and not move along as fast as it should jon.

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 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. If too little slope even if the water drains it won t be self cleaning i e. The only aci document that discusses slope of exterior patio slabs is aci 302 1r 04 1 it states that.

But the reason for including any fall rather than making the surface level is to allow the concrete surface to drain. 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. 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.

The standard slope for proper concrete drainage is a one quarter inch drop for every foot of length. 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. To calculate this multiply the length in feet of the farthest wall from the drain and multiply that result by 0 125. 4 drain pipes should be about 1 4 inch per foot.

You need 1 4 inch of slope for every linear feet of floor space. For example a floor that extends 4 feet away from the drain should have 1 inch of overall slope. If the slope is more gradual than this you may run into trouble getting water to run off properly.