Everything You Need To Know About Road Kerbs And Channels
Thu Aug 21 2025
While they might just appear to be simple concrete edges, the kerb and channel systems lining our roads and properties are quietly fulfilling their essential yet often overlooked duties of protecting our investments, ensuring our safety, and preserving the functionality of our roading infrastructure.
Read on to find out more about why quality kerbing and channelling matters, explore its practical applications, the different types, and learn more about the installation process.
What Are Kerbs And Channels And What Is Their Purpose?
Kerbing is an essential element of roadway construction designed to provide physical separation between roadways, pedestrian areas, cycle lanes, median strips and more. Kerbing provides a physical barrier that is visible and durable for vehicles and pedestrians, but it also serves other purposes as well.
What Does A Kerb Do?
At its core, a well-designed and installed kerb and channel system serves four primary functions, each essential for the longevity and functionality of your property and the surrounding infrastructure.
1. Drainage Management
One of the most important functions of kerbing is the management of storm water (particularly important in NZ where we are prone to sudden downpours!) The ridge and channel formation of kerbing allows for water run-off to be directed into the appropriate drainage systems.
Without a properly constructed drainway, it is likely that excess rainwater could flood or pool uncontrollably on the road’s surface, creating hazardous conditions for motorists and pedestrians, and could even lead to damage to properties and roads.
2. Safety Enhancement
One of the primary roles of road kerbing is to provide a strong visual cue for drivers, especially during low visibility conditions (at night or in heavy fog). Kerbs help drivers understand where the road edges are, avoiding the possibility of unknowingly veering onto shoulders or footpaths. This clear distinction aids in preventing accidents and ensuring the safe movement of vehicles and pedestrians alike.
In residential roading environments, kerbing can also be used strategically for traffic management purposes. Raised medians can separate opposing lanes of traffic, avoiding collisions and improving traffic flow and separation of traffic at intersections or turning points can be achieved, enhancing safety and efficiency.
3. Erosion Control
Erosion can pose a significant threat to landscapes, roadways and properties. Kerbing acts as a strong physical barrier, preventing the uncontrolled flow of water across the surrounding area. By intercepting surface run-off from the road, it reduces the speed and volume of water that could potentially wash away topsoil, destabilise slopes, and undermine landscaping efforts.
Over time, it is possible this erosion could weaken the roading sub-base, lead to cracking or potholes, and even compromise the structural integrity of the road and surrounding footpaths and driveways.
4. Boundary Definition And Aesthetic Appeal
Beyond its more practical applications, kerbing plays a part in clearly defining property boundaries and adding a sense of visual appeal to the landscape. A well-defined kerb is useful for separating the different landscape elements, such as lawns, gardens, and driveways and defining property boundaries, aiding in enhancing the overall tidiness and aesthetic appeal of your property.
The consistent and well-aligned application of kerbing also provides a clear distinction between private property and public walkways or roadways, contributing to a sense of community and well-maintained surroundings.
Types Of Kerbs And Channels In NZ
The most common type of kerbing in New Zealand is concrete kerbing. It is favoured for its durability, versatility and cost-effectiveness in all kinds of terrain and environmental conditions. This is because concrete kerbing offers excellent weather and impact resistance, and can also withstand the daily stresses of vehicle traffic. There are two main construction methods for concrete kerbs:
- Extruded Concrete Kerbing - Involves using a specialised machine to continuously form a concrete kerb directly on-site. This method offers greater flexibility all around and is usually more cost-effective for long distances.
- Pre-Cast Concrete Kerbing - Manufactured off-site in controlled environments, ensuring consistent quality and strength.
Both of these methods are available in a wide range of kerb and channel profiles in NZ, including but not limited to:
Low Or Mountable Kerbs
Mountable kerbs are designed to provide edging for road surfaces with a low profile that provides easier access for drivers to enter the shoulder area or driveways. Low or mountable kerbs are typically around 70-80 mm high, meaning they are easy to drive over without causing damage to the vehicle. This type of kerb is predominantly found in residential areas.
Barrier Kerbs
There are two types of barrier kerbs - low speed and high speed. Low-speed barrier kerbs are designed to prevent slow-moving or parked vehicles from entering the footpath area. They are typically higher than mountable kerbs, which makes them a more effective barrier. High-speed barrier kerbs are designed to provide a strong, visible barrier for vehicles travelling at high speeds. You will typically find them used in critical traffic areas, such as bridges or busy roads, where safety is a top priority. These kerbs or median strips range in height from 230 to 450 mm and are designed to withstand collision impact.
Channel Kerb (Or Kerb And Channel)
Channel kerbs are a combined type of kerbing featuring both a vertical kerb face and an integrated channel for stormwater run-off. Many suppliers offer a variety of profiles (shapes and sizes) to best fit the application and desired effect.
Dish Channels
A kerb type that focuses on efficient water drainage with a more pronounced channel. V-Channel, deep, and hillside dish channel variations exist within this classification.
Nib Kerb (or Kerb and Nib)
A type of kerb and channel featuring a smaller upright section (nib) alongside the main kerb and channel. Low-profile versions are also available.
Submerged Kerbs
Submerged kerbs are designed to provide lateral stability for pavements on rural roads. They are typically made from concrete blocks placed between the edges and shoulders of the road. They are designed to provide lateral support for base course, preventing erosion and controlling water run-off.
Landscaping Kerbing
Often referred to as garden edging, this type of kerbing is a popular choice for residential properties for the purpose of creating attractive edges in landscaping efforts to define garden beds, pathways, and lawns.
Installation Of Road Kerbing And Channelling
The proper installation of road kerbing is essential for its performance and effectiveness over the longer term. The kerb installation process generally involves the following 5 key steps.
1. Site Preparation And Excavation. The first step is clearing and excavating the area where the kerbing will be installed. This process will involve taking into account the required dimensions of the kerbing to be installed and the necessary base materials while also ensuring the site has adequate access.
2. Base Preparation. The formation of a stable and well-compacted base is very important for supporting the kerbing and preventing uneven settling. Depending on the soil conditions and expected traffic loads, this base may consist of compacted granular materials or a concrete sub-base.
3. Kerb Laying And Alignment. Pre-cast kerbing pieces are installed on the prepared base, ensuring accurate alignment and levelling using surveying techniques. For extruded concrete kerbing, the machine forms the kerb directly onto the prepared surface. Proper jointing materials are applied to prevent movement and cracking.
4. Channel Formation. If not part of a combined kerb and channel unit, channels are formed alongside the kerb after its installation. The channel must have a smooth and consistent gradient to facilitate water flow towards drainage solutions.
5. Backfilling And Compaction. Once the kerbing and channelling are in place, the surrounding areas are backfilled with suitable materials and properly compacted to provide support and prevent erosion.
Kerb And Channel Rules, Regulations And Standards In NZ
A range of regulations and standards governs the design and construction of road kerbing and channelling in New Zealand to ensure safety, durability, and functionality. Developers and contractors involved in road construction must be familiar with and comply with these relevant regulations and standards to ensure their work meets the required safety and performance criteria.
Consent and approvals from your local council will be required before undertaking any road construction or repairs involving kerbing and channelling. The main organisations involved in the process are:
- Local Councils. City and district councils have their own bylaws and specifications for road infrastructure within their jurisdictions, including requirements for kerbing and channelling in residential and local roads. These may vary depending on local conditions and priorities.
- Waka Kotahi NZ Transport Agency. The NZTA sets national standards and guidelines for road design and construction, including specifications for kerbing and channelling on state highways and other significant roads. Their standards aim to ensure consistency and quality across the national road network.
- New Zealand Standards. Various New Zealand Standards provide technical specifications for concrete, aggregates, and other materials used in kerbing and channelling construction. Adherence to these standards ensures the use of quality materials and construction practices.
At Letton Kerb & Channel, we are passionate about providing high-quality commercial and residential kerb and channel solutions tailored to the specific needs of New Zealand businesses. Call today to discuss your kerb and channel options nationwide.
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Page: Everything You Need To Know About Road Kerbs And Channels - Last updated: 3rd February, 2026
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