On a commercial channel drain, the grate's load class decides what can drive over it. A grate rated for foot traffic will crack under a delivery truck. A heavy-duty grate on a pedestrian plaza costs more than it needs to and may catch heels. This guide covers the AS 3996 load classes and how they apply to the 200mm and 300mm clear-opening channels PSA stocks from Allproof Industries. It also explains why the concrete around the channel matters as much as the grate.
AS 3996 load classes at a glance
AS 3996 sets load classes for access covers and grates. The figures below are from Allproof's published summary of the standard:
| Class | Typical traffic | Wheel load | Ultimate design load |
|---|---|---|---|
| A | Pedestrians, cyclists | 330 kg | 10 kN |
| B | Light vehicles: cars, utes, residential driveways | 2,670 kg | 80 kN |
| C | Light commercial, slow-moving vehicles | 5,000 kg | 150 kN |
| D | Heavy commercial: trucks, loading bays | 8,000 kg | 240 kN |
| E | Extra heavy: industrial yards, heavy vehicles | 13,700 kg | 400 kN |
The standard also has Classes F and G for very heavy loads, such as ports and airfield pavements. None of the channels in this guide is offered at those classes.
The grate rating only holds with the right concrete surround
These channels are designed to take their strength from the concrete they're cast into. A Class D grate in a channel with too little concrete around it is not a Class D drain. Allproof's install details specify:
- Commercial Channel CC200: at least 100mm of concrete surround for Class A–B, and 150mm for Class C–D.
- Allproof channels in general: from a minimum of 100mm surround for Class A up to 200mm for Class E.
Always follow the current install drawing for the grate and class you're using, and the engineer's details where the job has them. Grates on vehicle-rated runs should also be bolted down so traffic can't lift or shift them. The CC300 uses grate fixings, and the polymer concrete range comes with lock-down bars and bolts.
200mm clear opening: CC200 and PC200
Commercial Channel CC200 (recycled polypropylene, 100mm or 150mm deep)
The CC200 Commercial Channel comes in 1m clip-and-connect lengths with a stainless or galvanised edge rail. Allproof's ratings for its grates are:
- Glass-filled plastic (GFP), Class A: pedestrian areas only.
- 316 stainless wedge wire (WW B), Class B: Allproof lists Class B as standard and Classes C–D on request. The versions PSA lists are the Class B grates.
- Heelproof cast iron (HCI), up to Class D: suits car parks, loading bays and other commercial vehicle areas. The narrow slots also suit pedestrians.
- Galvanised grate (GAL): the listing doesn't state a class for the 200mm galv grate. Confirm it with PSA before you specify it for vehicle traffic.
The 150mm depth carries more water than the 100mm. The 100mm depth needs less excavation where there's a slab or services below. A 150-to-100mm joiner, inline sump, end caps and levelling clips are all on the same listing.
Polymer Concrete Channel PC200 (225mm deep)
The PC200 polymer concrete channel is for harder-wearing sites: loading docks, industrial yards, factories and breweries. Polymer concrete has very low permeability and resists chemicals. Grate options are cast iron, heelproof cast iron, 316 stainless wedge wire, 304 stainless laser-cut and 304 stainless ladder. The cast iron options come with a cast iron edge and the stainless options with a stainless edge. Allproof tests these grates to AS 3996 at ratings from Class A to Class E. The class depends on the grate, so confirm the rating of the grate you choose before you specify it. This matters most for Class E.
300mm clear opening: CC300
The CC300 Commercial Channel is 300mm wide and 150mm deep. It suits large hard-surfaced areas where a 200mm channel can't catch enough runoff. Allproof's grate ratings are:
- Heelproof cast iron (HCI), Class D: for commercial vehicle traffic, with a P5 slip-resistance rating. It comes with a stainless or galvanised edge.
- Galvanised steel (GAL), Class B: the budget option, with a large open area for good flow. Use it for cars and light vehicles, not trucks.
- Stainless wedge wire (WW B), Class B: a clean finish for forecourts and entries with light vehicle traffic.
Matching the class to the site
| Site | Minimum class | 200mm options | 300mm options |
|---|---|---|---|
| Plazas, courtyards, pool surrounds | A | CC200 GFP or wedge wire | CC300 wedge wire or galv |
| Residential driveways, car-only areas | B | CC200 wedge wire or HCI | CC300 galv or wedge wire |
| Car parks with vans and light trucks | C | CC200 HCI, PC200 cast iron | CC300 HCI |
| Loading bays, truck access | D | CC200 HCI, PC200 cast iron | CC300 HCI |
| Industrial yards, heavy vehicles | E | PC200 with an E-rated grate | None of the 300mm grates is rated E |
Treat the table as a starting point. Forklifts with small hard wheels and turning or braking trucks can load a grate harder than the same weight rolling straight over it. Where that applies, or where the site needs certification, the engineer chooses the class.
Common mistakes
- Too little concrete. A grate is only as strong as the surround in the install detail.
- Cast iron next to asphalt, bitumen or acid-washed surfaces. Allproof advises against using its cast iron grates with these finishes.
- Choosing on width alone. The clear opening controls how much water the drain catches. The grate class controls what can drive over it. Check both.
- Using a pedestrian-rated lid in a driveway. Pump pits and sumps have load classes too. For example, the Hyjet Minipit range comes with Class A grates for pedestrian areas only.
You'll find every channel in this guide in Exterior Channel Drainage Systems, and the wider range in All Drainage. If the channel feeds a pump, see choosing a drainage or sump pump.
Frequently Asked Questions
What load class do I need for a driveway channel drain?
A residential driveway with cars and utes needs at least Class B. A commercial driveway used by delivery vans or trucks needs Class C or D, depending on the vehicles. The concrete surround in the install detail also has to be right.
Is a heelproof grate weaker than a standard grate?
Not necessarily. Allproof's heelproof cast iron grates for the CC200 and CC300 are rated up to Class D. The narrow slots catch less water per metre than an open grate, but they're safer for pedestrians and wheelchairs.
Can I use the 300mm Commercial Channel in a heavy industrial yard?
The CC300's strongest grate is the heelproof cast iron at Class D. Areas that need Class E call for a channel with an E-rated grate, such as the PC200 polymer concrete channel. Confirm the rating of the specific grate first.
Does the grate class cover the whole drain?
No. The class only holds when the channel is set in the concrete surround the install detail calls for. Allproof specifies from 100mm of surround for Class A up to 200mm for Class E. The grates also need to be bolted down on vehicle-rated runs.