What Concrete Specifications are Best For Your Parking Lot?

Everyone understands the importance of a proper, strong building foundation, but don’t overlook the durability of your future parking lot. Whether you are determining specifications for a light or heavy-duty lot, concrete is an optimal solution. Some advantages include low maintenance, surface reflectivity of more light, and long-term resilience.

Here are the top items to analyze when it comes to choosing the most ideal specs for your commercial property parking lot concrete.   

Concrete Slab Thickness

Yes, the rule of thumb should be to check the municipality code in which your property lies, but that may not be thick enough sometimes. There are various factors that will affect your desired thickness. A main point to take into account is the purpose of the lot; i.e. truck stop parking will require a substantially thicker slab than residential.

Other Considerations:

• • Weight/volume of the anticipated traffic 
  • Drainage
  • Quality of soil 

Weight Capacity

Most parking garages only post the maximum height clearance. Weight restrictions would be helpful when it comes to safety and longevity, but it is not common. So, structural engineers must account for the possibility of excessive loading. This should also cover the proper structural reinforcement in the concrete line rebar or wire mesh. Reinforcing concrete mesh is an essential component of concrete structures.

Though each project will vary, we always recommend hiring an experienced structural engineer or partner with a developer that has completed the same type of lot or garage you are needing.

Quick Facts: 

• • The average vehicle in the United States today weighs about 4,000 pounds.
  • Snow can add a weight of 20-30 pounds per cubic foot (pcf), so don’t forget to factor in precipitation.
  • Understand these other examples of issues that caused disastrous collapses. 

Lighting & Reflectivity

It’s no surprise that lighter colored concrete will reflect more sunlight than dark asphalt, but it’s important to realize this extends to the light fixtures in the parking lot, too. Electing to have lighter concrete leads to energy savings due to the reduced cost in luminaires, or electric light units.

Heat Island Effect: 

• • Buildings, parking lots, and other infrastructure absorb and re-emit the sun's heat more than landscapes or bodies of water.
  • Asphalt would be worse as its surface temperatures could reach up to 140 degrees Fahrenheit! 
  • At this point, residue can become soft and get stuck to the soles of shoes.  

A Note About the Revised ACI 330R-08 Standard

The industry-supported document specially for parking lots has been revised to now differentiate parking lots from roads. This also means revised project criteria, reducing the subbase requirements. 

Under the updated standard, parking lots should have concrete pavement of at least five inches deep. Note: There is still a subbase below the concrete.

Modifications: 

• • The areas around dumpster pads and loading docks may need to be up to 12 inches thick. 
  • If heavyweight trucks will be allowed in the lot, the thickness must be increased.
  • For more heavy-duty lots, this standard specifies 6.5 inches over a compacted earth base. 

Not sure whether concrete or asphalt would be better for your parking lot? Weigh out the pros and cons before you get started.

For info on concrete slab thickness for a single-floor building, check out this blog post.