Specifying Commercial Linear Drains: A Practical Guide for Builders and Architects

Commercial drainage specification is not the same as residential. The load requirements, material standards, channel sizing, and compliance documentation are all different, and a drain that's perfectly fine in a home bathroom will fail in a commercial kitchen or a public amenity block within months.

This guide covers what to consider when specifying linear drains for commercial projects, from grate load class through to custom sizing and documentation.

Why commercial projects need a different specification

The main differences come down to three things: load, volume, and longevity. Commercial drains are subject to higher foot and vehicle traffic, greater water volume in shorter periods, and more aggressive cleaning regimes than residential drains. A specification that doesn't account for these factors leads to grate failure, channel corrosion, or drainage backups.

Getting the specification right from the design stage avoids costly replacements and ensures the drainage system performs for the life of the project.

Load class selection

AS/NZS 3996 classifies grates and access covers by load class. For commercial linear drains, the relevant classes are:

• Class A: pedestrian areas only, no vehicle access
• Class B: light vehicle areas, car parks, light driveways
  
• Class C: medium vehicle access, service vehicle areas
• Class D and above: heavy traffic, plant access, public roads

For most commercial wet areas, including hospitality, aged care, healthcare, and public amenities, Class A is the minimum. If the area is accessible by delivery vehicles, forklifts, or any wheeled plant during or after construction, specify Class B or above.

Grate material for commercial applications

Material selection affects both the performance and the maintenance burden of the drainage system over time.

316L stainless steel is the standard for commercial wet areas. It handles repeated chemical cleaning, continuous water exposure, and coastal conditions. 304 grade is suitable for dry or semi-exposed areas but not for pool surrounds, commercial kitchens, or any application with ongoing chemical contact.

Wedge wire grating is worth specifying for commercial applications where slip resistance is a priority. Strip Drains' wedge wire drainage has been independently tested to the P3 slip resistance rating under AS 4586, making it compliant for commercial wet areas where a P3 rating is required. See our post on wedge wire drainage and P3 slip resistance for detail on what this rating covers.

Solid brass is available for commercial projects where the finish needs to complement a specific interior or exterior design intent. Solid brass is a distinct product from stainless steel. If your specification calls for brass drainage, confirm this with the manufacturer before documenting it.

Custom channel sizing for commercial projects

Standard residential drain widths (70mm to 115mm) are often insufficient for commercial applications with high water volumes or long channel runs. Custom channel sizing allows the hydraulic engineer or architect to specify the exact channel depth, width, and length required to meet the drainage demand.

Key dimensions to confirm at specification stage:

• Channel width (internal clear dimension)
• Channel depth (to allow adequate gradient and outlet connection)
• Total channel length, including any right-angle junctions or end caps
• Outlet size and position (base or end outlet, outlet diameter)
• Grate width to match finished floor tile or paver module where applicable

Our guide on how to measure and specify a custom linear drain walks through the measurement process. For long channel runs, see our planning guide on strip drainage over 3 metres.

Common commercial applications

The specification requirements vary by application type. Some of the most common:

Commercial kitchens: High water volume, hot water, heavy cleaning chemicals. Specify 316L stainless steel, removable grate for cleaning access, base outlet to connect to floor waste system.

Hospitality and retail: Aesthetic finish matters more here. Consider polished stainless or solid brass to match the fit-out, with tile insert grate options where the drain needs to disappear into the floor finish.

Aged care and healthcare: Accessible design is a requirement. Specify heelguard grating (maximum 8mm opening) where the drain falls within a path of travel or accessible wet area. See our heelguard grating specification guide for compliance requirements.

Public amenities and change rooms: High foot traffic with wet conditions. Specify P3-rated grating, heelguard opening sizes, and 316L stainless steel as standard.

Pool surrounds and wet decks: The combination of pool chemicals, bare feet, and continuous water exposure makes pool surround drainage one of the more demanding specifications. Our post on commercial pool surround drainage covers this application in detail.

What to include in a commercial drain specification

A complete specification document for a commercial linear drain should include:

• Product type (tile insert, wedge wire, heelguard, or flush grate)
• Material and grade (316L stainless, or solid brass)
• Grate load class per AS/NZS 3996
• Slip resistance rating (ours are slip tested to AS 4586) where applicable (P3 per AS 4586 for wet pedestrian areas)
• Maximum grate opening size where heelguard compliance applies
• Channel dimensions (width x depth x length)
• Outlet diameter and position
• Finish (polished, matte)
• Any custom sizing or junction requirements

Talk to us about your project

Strip Drains manufactures custom linear drainage for commercial projects across Australia. We can provide specification documentation, DXF files, and product data sheets to support your tender or DA submission. Contact the team to discuss your requirements.