RP Tip: Understanding the 24" Curb

Concrete Curb & Gutter Services Raleigh

Curbing that Borders on Perfection

Adding a border to your parking lot or road, concrete curb and gutter is the standard in North Carolina. Do it the right way with Raleigh Paving. Our experienced team, attention to detail, and full-service solutions will make your curb or gutter project a breeze. Contact us today to learn more and get started!

Benefits of Curbing

  • Define water flow to points of collection, such as storm drains, to keep your parking lot from flooding and to help reduce erosion.
  • Strengthen the edge of your asphalt, protecting shoulders by keeping traffic contained.
  • Provide a protective barrier against steep lot drop-offs.

Considerations & Corrections

Attention to grade is vitally important to laying new curb and gutter. Not only for the flow along the curb, but the flow between receiving and spill points through other surfaces such as the parking lot and landscape areas. It is not unusual for us to arrive at a job in which the curb and gutter was already placed by others, that we find grade issues that involve replacing curb that creates problems for the new surfaces.

Handicap areas out of spec or not enough pitch to the drains through the parking lot are also common problems. Different surfaces need different percentages of pitch to keep water flow moving at a reasonable rate. As with all concrete applications, quality of craftsmanship varies considerably from contractor to contractor. We can assure you that our team is ready to address any previous issues with your curb and prevent any future ones!

 

Contact the team at Raleigh Paving today and speak with one of our paving experts about your concrete project!

Typical Curbing Practice in NC

curb_and_gutterIn North Carolina, the type of curbs that are used do not vary much. “24” Curb and gutter” probably represents 90% of all curb installations in the state. But why is this? There are many other types of borders that might perform just as well if not better. As you travel north or south from North Carolina, the type of curb that is prevalent in each state varies. The look can differ slightly by changing the width of the pan or its inset radius, or sometimes the shape of the upright portion may vary too. In some instances, there may not be a pan at all. The pan, if you don’t know, is the horizontal portion of the “curb and gutter” system also referred to as the gutter.

To completely understand this situation, it’s important to understand what a curb is and why curbs are used. The National Ready Mixed Association defines a curb this way.

A curb, by definition, is something that restrains; an enclosing border or edging; a raised edge or margin; a wall; or as a verb, to strengthen or confine something. As most people think of curbs, they are raised strips of concrete along the edges of streets or parking lots. The benefits of curbs have been recognized since ancient times, and stone curbs were placed along the edges of traveled ways by early civilizations. Today’s concrete curbs still provide many of the same benefits and more. – http://www.concreteparking.org/curbs/index.html

Based on this definition, we can begin to list some of the benefits that curbs offer:

  • Help to define water flow to points of collection such as storm drains. This reduces erosion and allows water to move at lower percentages of grade.
  • Add visual appeal by providing sharp demarcations between different types of surface.
  • Strengthen the edge of flexible pavement systems such as asphalt by minimizing erosion and containing the pavement subsystem.
  • Protect shoulders by keeping traffic contained.
  • Improve the visibility for drivers.
  • Provide a protective barrier to steep drop offs.
  • There are other benefits to curbs but these are main reasons road authorities or owners of parking lots install curbs. However with all these benefits, shouldn’t the type of curb vary by priority for a given situation? You would think so. At least I think so.

When first moving to North Carolina from New York State I could not understand why all the curb was the same. After all, we used to build the curb custom to the situation it was serving. Often because of the harshness of the winters, we would add rebar, increase the thickness or put it deeper into the ground. We did valley curb, curb and gutter, upright curb, median curb and many other types of curbs. On just about every job, the curb detail was one of the most important details. In North Carolina, we hardly give the curb detail a second thought. It’s just always the same. Why??

It is difficult to definitively answer this question but after having been here for 10 years now I can, at least, begin to conjecture. Perhaps it is because 24″ curb and gutter just seems to work here 95% of the time. I have seen very few situations where for one reason or another it did not work. In just about every situation across the board including mainline roads it does the job. As a result, every concrete crew knows how to form and pour curb and gutter. Every curb crew with a curb machine has the standard form that meets the NCDOT spec for this curb. This brings down costs through familiarity and, in my opinion, the NCDOT and engineers throughout the state know that prices from contractors go up when they are bidding on details that are foreign to them. Over time this particular iteration of curb and gutter just seems to have won out with everybody.