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Legal & user requirements


Building thresholds are highly trafficked making access and mobility an imperative consideration. Designers must cater for a diverse occupancy driven by a number of factors including an ageing population as well as disability requirements. Level threshold drainage in buildings facilitates access and eliminates the need to have conventional step downs that were once used to contain stormwater runoff.

There are a number of regulatory and user requirements that designers must be aware of when specify drainage channels.

AS 1428.1:2021 includes, Section 4 Floor or ground surfaces on continuous accessible paths of travel and circulation spaces, with Clause 4.4 Grates which states the following:

“Grates in paths of travel shall be in accordance with the following:

(a)  Circular openings shall be not greater than 13mm in diameter.
(b)  Slotted openings shall be not greater than 13mm wide and not greater than 150mm long and be oriented so that the long dimension is transverse to the dominant direction of travel.
(c)  Linear openings shall be oriented so that the longer dimension is transverse to the dominant direction of travel, except where linear openings are less than 8mm wide.  Where linear openings are less than 8mm wide, orientation is optional.”

compliance clauses

If the grates meet AS 1428.1, they are deemed to comply with DDA requirements.

To learn more about wheelchair and walking cane compliance, visit ACO’s education pages.

Slip resistance

With the increase in litigation and compensation for injuries caused by slips, trips and falls, designers must consider specifying grates and floor surfaces that comply with AS 4586 – Slip resistance classifications of new pedestrian surface materials. It is important for designers to specify a grate that is relevant for the application with a suitable slip resistance rating.

The perception that a higher slip resistance rating will provide a better solution is incorrect. Trip hazards can be introduced where a grate has a higher slip resistance than the surrounding floor surface, or vice versa. ACO recommends grates to have the same level of slip resistance as the surrounding floor.

The slip resistance of Tile and Brickslot grates depend on the slip resistance of the infill material specified. In order to measure the slip resistance of a grate or floor surface, three tests are specified in AS 4586.

  • Wet pendulum: Applied to pedestrian areas that can become wet with rainwater.
  • Wet-barefoot inclining platform: Applied to wet areas where footwear/shoes are not worn. For instance at pools, waterparks, beach areas etc.
  • Oil-wet inclining platform: Applied for commercial and industrial areas that can be contaminated with oil or grease e.g commercial kitchens.

Slip resistance standards

The National Construction Code (NCC) requires and specifies minimum slip classifications for certain, high-risk areas. The table below is adapted from the National Construction Code 2016, volume 1 and 2.

In 2014, Standards Australia published a supporting handbook, HB 198:2014 Guide to the specification and testing of slip resistance of pedestrian surfaces, which provides recommendations and guidance for specifying surface materials that suit different application requirements. The adjacent table details guidance from HB 198. To assist designers in specifying grates with adequate slip resistance, ACO has commissioned and independent third party authority to test and rate each of its grates to AS 4586.

LocationWet pendulum
Dry surface
Wet pendulum
Wet surface
Wet ramp
Dry surface
Wet ramp
Wet surface
Ramp steeper than 1:14P4P5R11R12
Ramp steeper than 1:20, but not steeper than 1:14P3P4R10R11
Ramp not steeper than 1:8P4P5R10R12
Tread surfaceP3R10R10R11
Nosing or landing edge stripP3-P4-
pendulum test
platform test
External Pavements and Ramps
External ramps including sloping driveways and footpaths steeper than 1:14P5R12
External ramps including sloping driveways and footpaths, etc., under 1:14, external sales areas (e.g. markets), external carpark areas, external colonnades, walkways, pedestrian crossings, balconies, verandas, carports, driveways, courtyards and roof decksP4R11
Undercover car parksP3R10
Hotels, Offices, Public Buildings, Schools and Kindergartens
Wet areasP3R10
Transitional areasP2R9
Dry areasP1R9
Toilet facilities in offices, hotels and shopping centresP3R9
Hotel apartment bathrooms, en-suites and toiletsP2A
Hotel apartment kitchens and laundriesP2R9
Supermarkets and Shopping Centres
Fast food outlets, buffet food areas, food courts and dining areas in shopping centresP3R10
Shops and supermarket fresh fruit and vegetable areasP3R10
Shop entry areas with external entrances P3R10
Supermarket aisles (except fresh food areas)P1R9
Other separate shops inside shopping centres – wetP3R10
Other separate shops inside shopping centres – dryP1R9
Loading Docks, Commercial Kitchens, Cold Stores, Serving Areas
Loading docks under cover and commercial kitchensP5R12
Serving areas behind bars in public hotels and clubs, cold stores and freezersP4R11
Swimming Pools and Sporting Facilities
Swimming pool ramps and stairs leading to waterP5C
Swimming pool surrounds and communal shower roomsP4B
Communal changing roomsP3A
Undercover concourse areas of sports stadiumsP3R10
Hospital and Aged Care Facilities
Bathrooms and ensuites in hospitals and aged care facilitiesP3B
Wards and corridors in hospitals and aged care facilitiesP2R9
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