When designing a trench drain system, choosing the correct load class rating is critical. Whether you’re draining a residential driveway or an airport tarmac, your trench drain and grate must be able to withstand the physical loads it will encounter daily.
Improper selection can lead to system failure, safety hazards, and expensive repairs. In this guide, we’ll break down what load class ratings are, where they apply, and how to choose the right one for your application.
You’ll also find links to our grate load class chart, product pages, and trench drain sizing tools to support your design and purchasing decisions.
What Are Trench Drain Load Class Ratings?
Load class ratings are standardized categories that define the weight and force a trench drain grate can support without failure. These classes are determined by international standards such as:
- EN 1433 (European standard for drainage channels)
- ASTM A1014 / A1017 (U.S. standard for grating and cover plates)
They ensure that trench drain systems are appropriately rated for the vehicles, machinery, or foot traffic that will cross them.
Why Load Class Ratings Matter
- Prevent system collapse or grate deformation under weight
- Ensure pedestrian and vehicular safety
- Avoid liability from trip-and-fall or structural damage
- Maintain compliance with local building codes and engineering standards
Using an under-rated grate can result in structural failure, while over-specifying can lead to unnecessary cost. Proper selection ensures both safety and cost-efficiency.
Overview of Common Load Class Ratings
|
Load Class |
Weight Capacity (lbs) |
Description |
Example Applications |
|
A15 |
Up to 3,300 lbs |
Pedestrian use only |
Walkways, patios |
|
B125 |
Up to 27,500 lbs |
Light traffic |
Residential driveways |
|
C250 |
Up to 55,000 lbs |
Medium-duty |
Commercial parking lots |
|
D400 |
Up to 88,000 lbs |
Heavy-duty |
Truck loading docks |
|
E600 |
Up to 132,000 lbs |
Industrial traffic |
Forklifts, factories |
|
F900 |
Up to 198,000 lbs |
Aircraft or crane use |
Airports, ports, railyards |
Visit our trench drain load class chart for expanded technical details.
Matching Load Classes to Real-World Applications
Load Class A15: Pedestrian Use
Best for:
- Garden walkways
- Pool decks
- Parks and residential landscaping
Grates are typically made of HDPE or aluminum, with light-duty channels. No vehicular use.
Load Class B125: Light Residential Traffic
Best for:
- Driveways (cars, SUVs)
- Garage thresholds
- Light-duty walkways
Grates are commonly galvanized steel or HDPE. Compatible with polymer concrete or HDPE channels.
View our residential trench drain systems for B-rated options.
Load Class C250: Light Commercial Traffic
Best for:
- Retail and Commercial parking lots
- Office complexes
- Apartment entryways
Supports small trucks and commercial service vehicles. Grates typically ductile iron or galvanized bar.
Load Class D400: Heavy-Duty Traffic
Best for:
- Warehouses
- Distribution centers
- Loading docks
- Fire lanes
Grates are usually ductile iron, slotted or bar style. Channels are polymer concrete or reinforced HDPE.
Browse D400-rated trench drain systems.
Load Class E600: Industrial Forklift Zones
Best for:
- Factories, loading docks and heavy duty applications
- Machine shops
- Ports and container yards
Designed to handle repetitive, point-loaded stress from forklifts, lift trucks, and industrial wheels.
Load Class F900: Airport and Crane Applications
Best for:
- Airport Runways and Hangars
- Rail yards
- Crane paths
- Military bases
These trench drain systems are engineered with steel frames and reinforced polymer or concrete bodies. Grates are ductile iron or steel composite.
Used in Swiftdrain’s airport trench drain projects.
Grate Materials and Their Load Ratings
|
Material |
Typical Load Classes |
Notes |
|
HDPE |
A15–B125 |
Lightweight, UV-resistant |
|
Galvanized Steel |
B125–C250 |
Affordable, rust-resistant |
|
Ductile Iron |
C250–F900 |
High strength, durable |
|
Stainless Steel |
B125–D400 |
Sanitary, corrosion-resistant |
|
Cast Iron |
C250–E600 |
Strong but brittle in extreme cold |
See material breakdown on our grate types guide.
Structural Considerations
Load capacity is affected not just by the grate, but by the entire system, including:
- Channel wall thickness and material
- Rebar anchoring and embedment
- Frame design (edge rail, ductile frame, etc.)
- Sub-base preparation and concrete pour depth
A D400-rated grate won’t perform to spec if installed in a shallow channel with poor base prep. Always follow best practices in our installation guide.
Misconceptions About Load Class Ratings
Myth: “A ductile iron grate is always heavy-duty.”
Fact: Grate material is only part of the equation. Channel strength, anchoring, and embedment are equally important.
Myth: “Residential applications don’t need load-rated grates.”
Fact: Driveways with delivery trucks, trailers, or RVs may require C250 or D400 grates.
Myth: “Load ratings are overkill for decorative projects.”
Fact: Even decorative grates can meet ADA and B125 standards for safety.
Cost vs. Performance
|
Load Class |
Average Cost (Per LF, System + Grate) |
|
A15 |
$45–$80 |
|
B125 |
$60–$100 |
|
C250 |
$90–$150 |
|
D400 |
$130–$200 |
|
E600 |
$180–$250 |
|
F900 |
$220–$300 |
Use our drainage cost calculator to estimate total system costs.
How to Specify the Right Load Class
- Identify the traffic type: Pedestrian, passenger car, truck, forklift, aircraft, etc.
- Determine frequency of use: Occasional or daily?
- Evaluate surface and slope: Does this system needs to be pre-sloped or neutral
- Check local codes or spec sheets: Ensure compliance with engineering requirements
- Use appropriate materials: Channel + grate + frame must match load class
Need help? Contact our technical sales team for a project-specific recommendation.
Summary
Choosing the correct load class is a foundational step in trench drain system design. It ensures durability, safety, and compliance over the long term—protecting both the project and the people who use it.
Whether you're building a simple walkway or a high-volume distribution hub, selecting the right combination of channel, grate, and frame based on load class is essential for success.
Next Steps
- Browse our full line of load-rated trench drain systems
- Use the trench drain load class chart to compare ratings
- Estimate material cost with our drainage calculator
- Reach out for engineering support or a custom quote
