Concrete curbs and gutters are like peas and carrots — together, they make a great pair.
Often an afterthought, these two concrete additions play an important role at a commercial site.
In this article, we’ll give them their time in the spotlight. We’ll discuss:
A gutter is a slanted slab of concrete accompanying the curb to draw water away from the site. Gutters eliminate the need for ditches and improve the lifespan of the roads, reducing water penetration.
This section will discuss the main commercial curb and gutter types and their benefits.
We’ll also reveal when it makes the most sense to use each curb and gutter combo type. For example, we’ll identify the types of projects that benefit from one over another.
Have you been trying to decide between two different types of curbs for your next project?
Then, good news! We’ll help you solidify your decision on the best one.
A barrier curb can also go by a few other names, such as a vertical curb or a straight curb.
These curbs are useful when you need a barrier between a roadway and the sidewalk or green.
Basically, this type of curb discourages drivers from leaving the roadway. Vertical curbs create a solid concrete barrier that would inhibit their tires from crossing.
These curbs are also good because they strengthen and support any poured concrete slabs connected to the curb.
Barrier curbs are more expensive than other curbs but also more durable, which makes the extra investment worthwhile.
In fact, you’ll see many barrier curbs used in commercial projects, especially near buildings, sidewalks, and parking lots.
Barrier curbs can feature several different edges. For example, they can be box-looking, have rounded edges, or appear fully rounded.
Mountable curbs are sometimes called rolled curbs or sloped curbs.
Adding these curbs saves money by reducing the need for vehicle crossovers. Are you thinking of adding driveways later on? If so, these curbs are the best choice since they’re less permanent in driveway design.
Mountable curbs are easier to drive over than barrier curbs but can still damage your vehicle, so you need to use caution.
Also known as a monolithic curb, flush curbs have a sleek look since they’re flush with the road or sidewalk.
Vehicles can park and drive on these curbs, making it a great choice for areas with a lot of loading and unloading expected.
However, these curbs do little to protect from erosion. So they aren’t the best for use next to grassy areas.
Of course, the idea behind flush curbs is that vehicles can drive on them, making them ideal to place next to paved areas where vehicles may want to enter.
The process of building curbs and gutters isn’t as simple as pouring a concrete slab. Yes, you’ll follow many of the same steps, but since the shape and size of curbs are so different, special attention to detail is necessary.
Below are the basic steps to follow when constructing curbs and gutters.
Before deciding on your curb design, the first step is to examine the subgrade soil.
There should be no loose soil where you plan to add a curb. You can use a mechanical compactor to get the correct soil compaction level.
The soil must also be at the right elevation and wet before applying the concrete.
Now is the perfect time to adopt a good habit, too. So before you begin, check your curb forms to ensure they’ve been properly maintained.
Forms should be smooth and free of debris or gouges. They also need to have a sharp upper edge and be strong enough not to buckle under the weight of the concrete.
Once your forms have passed all the listed criteria, oil them down with form oil to ensure easy breakdown after the concrete has dried.
For a full curb and gutter construction preparation checklist, check out the Department of Transportation’s guide.
Once your site is ready, it’s time to design your curb. There are a few things to consider when mapping out your design.
First of all, your design will need to meet building and regulatory specifications. It must also meet the requirements for pedestrian traffic safety.
Every state will have specific building codes that curbs and gutters must meet. These will dictate the thickness, width, and placement of curbs.
The Federal Department of Transportation provides technical drawings with measurements and specifications for several different curb construction scenarios.
Once you have your curb construction specifications, you’ll need to map out your curb placement.
Think about where your traffic will be the heaviest, both vehicle and pedestrian, and design your curbs to aid in this traffic flow.
Consider where to employ which type of curb and gutter, depending on your business needs and expected traffic areas. Determine where to add vehicle crossovers and ramps as well.
When tying curbs and gutters to concrete slabs, you’ll need to use rebar placed in both the slab and the curb. Doing so will help with load transfer and eliminate cold joints, which are weaker and prone to damage.
Otherwise, you’ll need to add expansion joints and filler when adding curbs to existing concrete slabs.
After solidifying your initial design, mark the outline with string guidance or marking powder.
You’re then ready to install the framework.
When you install the formwork, ensure that all reinforcements and dowels are in place at the correct marked area.
When you’re happy with your formwork, it’s time to pour the cement concrete premixed with aggregate into the formwork.
Here, you must measure the drying curb to ensure it meets slope specifications.
More details about the recommended slope and size for curbs and gutters in civil engineering are often available online.
One method worth considering is enlisting the help of a curb machine. This industrial equipment can save your crew a lot of time and effort.
A curb machine could also be known as a slipform machine since it requires no formwork and forms the curb as you use it. Slipform machines produce a more uniform and attractive-looking curb.
Curb machines also reduce material costs due to the elimination of wood and steel needed for formwork. Plus, less goes to waste since you pour concrete directly into the hopper.
A low-slump concrete formula goes into the hopper for the curb machine to use immediately. This concrete uses accelerators to speed up the hardening process.
Any other kind of concrete won’t work in a curb machine.
Alternatively, you can employ a curb roller to form a perfect curvature in certain curb types. Then, after you pour the concrete into the formwork, you’ll roll the drum along the curb face.
A curb roller is cheaper than a curb machine, is operable by just one person, and requires no special skills. You can also interchange various drums to create different curbs and gutters.
Without using any of these curb-making technologies, you’ll need to go in with finishing tools before the concrete is completely dry. Why? Well, you’ll need to smooth out some of the pavement edges.
Formed curbs must remain in the right environment for strong curing. Essentially, you must protect it from the elements, using protective barriers in the initial phases and water and covers near the end.
Additional methods are also available to manage moisture loss while curing concrete.
This depends largely on your desires and curbing uses. For instance, painting your curb can aid in the aesthetics of your commercial property or direct traffic.
You can paint some curbs yellow or red to mark an area reserved for certain parking abilities. And, of course, blue would denote handicapped access.
Painting your curbs white is simply for looks but can also help to highlight the curb and make it more visible, especially at night.
By now, you may wonder:
Is it worth investing all this extra time and money just to install a small line of extra concrete around your sidewalks or parking lots?
The only disadvantage that comes with the addition of curbs and gutters to your commercial project is the extra cost and need for skilled labor.
The advantages of curb and gutter installation more than outweigh the cost of construction.
Let’s discuss these.
One of the biggest benefits (in terms of construction) is that curbs add supporting compression to the concrete slabs they’re connected to.
The curbs maintain the integrity of the pavement edges, reducing any breakage or cracking due to blunt force impact from vehicles.
The gutters help with drainage, guiding rainwater into storm drains, which reduces water damage to the property. On the other hand, the curbs prevent soil erosion and clogging of drains from sediment in the water.
Overall, curbs and gutters increase the strength and stability of every aspect of landscaping. That includes the sidewalks, the parking lots, and the greens.
Curbs and gutters keep your site looking clean and professional. Your lot is the first impression you make on visitors. So it’s important to present a clean and organized area.
Curbs and gutters make cleanup easy for street sweepers since they have a definitive edge and a barrier to keep soil and trash within reach.
As we’ve already discussed, curbs and gutters keep water from piling up on the concrete or grass. (Sloshy, muddy grass and puddles on your sidewalks aren’t exactly inviting to your clients and customers.)
Lastly, the uniform look of curbs adds curb appeal to your commercial property. After all, the idea of a better-looking exterior facade has the word “curb” in it!
There’s another big reason to choose the addition of curbs and gutters where appropriate:
It adds to the safety of your property.
The curbs help to direct traffic, reducing the potential for crashes. They also help provide better night vision of driveway boundaries, especially when you paint them with a distinct color.
Some curbs, such as the flush curbs, add driving space without needing a slope.
Installing curbs and gutters on your next commercial project requires a little planning and extra construction cost. Yet, it’s well worth the investment, especially if you choose the right type.
Hopefully, by reading this article, you’ve been able to choose the best type for your project while learning the basics of curb and gutter construction.
Here at FMP Construction, we encourage all our clients to take advantage of the many benefits that curbs and gutters will add to their projects.