Bar Grating Stair Treads for Vancouver Industrial Stairs

Bar grating treads drain, let light through, and stay grippy when wet. On a Vancouver warehouse stair, that is often why they beat a solid plate. The nosing, the serration, and the galvanizing are the details that decide it.

Bar grating stair treads are the default tread for warehouse, plant, and access stairs because they drain water, let light through, and stay grippy when wet. The real decision on a Vancouver industrial stair is not whether to use grating, but which surface, nosing, and finish to specify, and where a solid or checker plate tread beats grating instead.

This post explains what bar grating treads are, the difference between serrated and plain, why grating drains better than a solid plate, how the nosing and galvanizing are detailed, what the BC Building Code asks for on an industrial stair, and the cases where grating is the wrong choice.

Bar grating treads are open steel steps

A bar grating tread is a step made from steel bar grating. Grating is a grid of parallel load-bearing bars, set on edge, held apart by cross bars welded or pressed across them. The bars carry the load along the tread. The cross bars hold the spacing and tie the panel together. Cut the panel to the stair width, add end plates and a front nosing, and it becomes a tread.

The open pattern is the whole point. Water, light, and small debris pass through the gaps between the bearing bars instead of sitting on the surface. On the switchback galvanized stair in the photo above, every tread is open grating, so nothing collects on the steps and the stair below still gets light.

Steel bar grating and grating stair treads are made to the ANSI/NAAMM MBG 531 Metal Bar Grating Manual, which sets the bar sizes, spacing, load tables, welding, tolerances, and standard tread nosings. A grating supplier such as Direct Metals lists these treads with plain or serrated surfaces and a choice of nosings, in galvanized, carbon steel, aluminum, or stainless. The shop drawing names the grating type, bar spacing, surface, nosing, and finish so the tread matches the load and the traffic.

Serrated grating grips a wet or oily stair

Grating comes in two surfaces, and the choice changes how the stair walks when it is not dry.

Plain grating is the flat top edge of the bearing bars. It is fine for a dry interior stair and it is a little easier underfoot. Serrated grating has a notched, toothed top edge on every bearing bar. Those small teeth bite through a thin film of water, oil, or grease, so the foot grips the metal instead of sliding on the film. The grating manufacturer offers both plain and serrated tops, with serrated aimed at areas prone to oil or other slip hazards.

For most Vancouver industrial and exterior stairs, serrated is the right call. Rain, wash-down, and tracked-in slush all leave a film on the tread, and serration is what keeps the stair grippy through it. Plain grating stays reasonable where the stair is indoors and dry. If you want a broader look at grip options, our guide to anti-slip finishes for exterior Vancouver stairs covers the choices for both grating and solid treads.

Drainage is why grating beats a solid plate

The strongest argument for grating on a Vancouver stair is water. A solid steel or checker plate tread holds water on its surface. That thin film of water, and the dirt and oil mixed into it, is what people slip on, and it is what freezes into a slick layer on a cold morning.

Open grating drains. Water passes straight through the gaps between the bearing bars and falls away, so the tread surface is wet metal instead of standing water. On an exterior stair in this climate, where treads sit under rain for much of the year, that difference matters every day. Grating also does not trap leaves, grit, and debris the way a solid tread with a raised lip does.

Grating is lighter than a solid plate of the same size too, which can matter for a long mezzanine run or a stair that has to be craned and bolted into place. Our overview of mezzanine stair design for Vancouver warehouses walks through where that weight and access saving changes the install.

This article is not a substitute for code review by the authority having jurisdiction, an architect, or an engineer.

The nosing is a separate, welded detail

Grating solves the drainage and grip problem across the middle of the tread, but it does not finish the front edge on its own. The open front bars at the nose are not a clean walking edge, so a nosing is added.

An integral nosing is welded to the leading edge of every grating tread. The common options are a checker plate strip, a cast abrasive nosing, or a grooved aluminum nosing. The nosing gives the foot a defined, solid edge to land on at the top of each step, and an abrasive or contrasting nosing marks that edge so users see where the tread starts. This is the detail that most affects how the stair feels the first time someone walks down it fast.

The nosing also carries the code detail at the front of the tread. On a stair that serves an occupancy other than a dwelling unit, the BC Building Code Part 3 exit and stair provisions set the rise, run, and nose geometry. A Building Code Appeal Board decision on Article 3.4.6.8 reads the rule as being about the riser and the nose: a step needs a closed riser or a limited rakeback, and where a nosing is provided it has specific limits. A welded front nosing on a grating tread is how the fabricator meets that detail. Confirm the exact requirement with the authority having jurisdiction, since the reading can turn on how the stair is classified.

The code governs the whole stair beyond the tread

The tread type is only one part of an industrial stair, and the BC Building Code governs the rest. For a stair serving an occupancy other than a dwelling unit, Part 3 sets the rise, run, guard, and handrail rules, and those apply whatever the tread is made of. A grating exit stair still has to hold the required run and rise, carry a compliant guard, and provide a graspable handrail.

Two grating-specific points come up at review. First, the opening size. Wide grating openings can catch canes, heels, small wheels, and mobility devices, so a stair or landing on an accessible route may need a smaller opening or a different surface. On a general industrial stair that is not an accessible path, a standard opening is usually fine. Second, the load. The grating has to be sized from the manufacturer’s load tables for the required loads of the occupancy, which is a design step, not a catalogue pick.

Because a required industrial stair ties into the building’s exit and life-safety design, the tread choice is confirmed alongside the guard, the connections, and the loads. Our piece on warehouse staircase safety and code in Vancouver covers the wider set of rules that a grating stair still has to meet.

Galvanizing is the default finish for wet use

For any grating stair that sees weather or wash-down, the finish is hot-dip galvanizing. The tread is dipped in molten zinc so every surface of every bar and cross bar is coated, inside the openings and out, to ASTM A123, the standard for hot-dip galvanized structural steel products. That full coverage is what protects a shape as complex as grating, where a brushed-on paint would miss the inner faces of the bars.

Galvanizing lasts. The American Galvanizers Association measures coating life as the time to first maintenance, the point where about 5% of the steel surface shows rust and a touch-up extends the life. In most atmospheric environments that time is measured in decades, so a galvanized grating stair rarely needs coating work for a long time. That long, low-maintenance life is a large part of why galvanized grating is the standard for exterior industrial access in a wet climate. For an interior dry stair, a powder coat or paint over the grating is sometimes used instead, mostly for appearance.

Where solid or checker plate is the better tread

Grating is not always right. The main reason to choose a solid tread is to stop things falling through. On a stair over a work area, walkway, or equipment, a dropped tool or part passing through open grating is a hazard, and a solid or checker plate tread closes that gap. Checker plate keeps a raised anti-slip pattern while staying solid.

The other reason is the look and the feel. Grating reads as industrial, and seeing through the open pattern from height bothers some users. Where a stair has to read as a finished interior element, or where comfort underfoot matters more than drainage, a solid tread wins. A grating tread with a solid infill panel is a middle option that keeps the grating frame but closes the surface.

The honest way to choose is to name the problem the tread has to solve. If the problem is water, grip, weight, or light, grating is usually the answer, and serrated galvanized grating with a welded nosing is the workhorse spec. If the problem is falling objects, a finished appearance, or comfort, a solid tread earns its place. Send the fabricator the occupancy, the loads, the exposure, and whether the stair is a required exit, and the tread choice follows from there rather than from a catalogue.

Sources

• BC Building Code Part 3, Section 3.4 Exits (Division B)
• BC Building Code Part 3, Section 3.3 Safety within Floor Areas (Division B)
• BC Building Code Appeal Board decision BCAB 1792, Article 3.4.6.8 stair nosings and rakeback
• Direct Metals, bar grating stair treads: surfaces, nosings, finishes, and NAAMM standard
• American Galvanizers Association, estimating the life of hot-dip galvanized coatings
• American Galvanizers Association, atmospheric longevity and time to first maintenance

Related reading: warehouse staircase safety and code in Vancouver, mezzanine stair design for Vancouver warehouses, and anti-slip finishes for exterior Vancouver stairs.

The strongest industrial stair specs start from the problem, not the part. Tell the fabricator the exposure, the loads, the occupancy, and whether the stair is a required exit, and the tread, nosing, and finish follow. On most wet Vancouver stairs, that path lands on serrated galvanized grating with a welded nosing.