Choosing an Exterior Grate: Single Slot, Double Slot, Trianglo or Ductile Iron

All four SKUs in WTI's exterior range share the same polymer concrete channel body, in the same 1000mm sections and load classes. The differentiator between them is entirely the grate — material and slot pattern — which means the choice comes down to sightline, flow capacity, and duty, not channel performance.

The narrowest sightline in the range. A single continuous stainless slot reads as a hairline rather than a feature — the right call for residential driveways, pool surrounds and pedestrian plazas where a discreet drain line matters more than maximum flow capacity.

The same channel with a twin-slot grating that roughly doubles the open inlet area. Suited to parking areas, basement ramps and campuses where surface water volumes are higher and a single narrow slot would undersize the inlet.

A triangulated slot pattern instead of straight parallel slots — the aesthetic pick where the drain run is visible and expected to contribute to the paving pattern, such as landscaped courtyards and entrance plazas.

The heaviest-duty grating in the range, prioritizing impact resistance and load rating over sightline. Specified for kerbside and road-edge drainage, and parking or ramp areas carrying repeated vehicular wheel loading — where a cast grate is the safer choice than a stainless slot.