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How-to: Properly Slope Concrete for Drainage

Why Slope a Concrete Patio or Walkway?

 

 

Sloping a concrete patio or walkway is critical to provide the drainage it needs. Concrete that is not sloped properly will not drain. This is great news for mosquitos, who will use pooling water as a breeding ground. And concrete that slopes toward your home, instead of away, can lead to rot and mold. The lesson: Before beginning a new project, make sure to account for proper drainage.

How Much Slope?

The standard slope for proper concrete drainage is a one-quarter inch drop for every foot of length. So, to calculate the difference in height between one end of a patio or walkway and another, simply multiply the length by one-quarter. This means the end of a patio protruding 10-feet from a home will drop two and a half inches from the starting point.

Oftentimes, a walkway will naturally tilt away from a home or other structure. But if it doesn’t, you need to account for proper slope to avoid water damage. A 4-foot wide concrete walkway that runs parallel to a house should drop one inch away from the home. If it’s running perpendicular to a structure, follow the one-quarter inch pitch for every foot of length rule. This will ensure water isn’t an unwelcome guest at your front door.

Other Considerations

Now, a caveat: One-quarter inch drop per foot is the standard measurement for concrete drainage. Depending on the surrounding conditions and the expected amount of precipitation, the slope can range from one-eighth to three-eighths per foot. In a drier climate? You can likely get by with one-eighth. Really wet climates may call for three-eighths per foot for proper drainage.

The surface’s exposure to sunlight and heat can impact the amount of slope as well. A sunbathed patio on the south or west side of your home will, of course, dry faster than a shaded concrete surface.

Alright, so there are a few conditions to consider when planning for concrete drainage. But—in addition to the amount of slope required for proper concrete drainage—there is the way in which a patio slopes to consider. Existing conditions like landscaping and neighboring properties will, in large part, dictate the direction in which a patio needs to slope for proper drainage (other than away from any structures). The goal is to ensure water sheds away from buildings or toward any drains.

laying concrete on slopes or patios

Conclusion

The takeaway? Carefully consider the expected precipitation, existing conditions and surrounding properties in order to ensure a finished concrete patio drains properly. Your efforts will not be in vain. A thoughtfully constructed patio or walkway that sheds concrete-corroding water will last for years.

In order to properly slope a concrete patio or walkway, simply pitch the forming according to the above calculations. Done and done . . .

This is all fine if you are planning a new project, but what if you’re stuck with a patio or walkway that doesn’t slope, or cants the wrong way? Unfortunately, the best solution to this problem is to remove and redo the concrete.

The good news? Intermountain Concrete Specialties has the knowledge, products and equipment needed to help with any of your DIY project needs. And with seven locations from St. George to Idaho Falls, help is never far away.

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