Gratings
Gratings are a type of covering or frame characterized by a textured surface, typically created through a series of holes, openings, or a grid-like pattern formed by intersecting bars.
The History of Gratings
The production and use of grates date back as far as the Bronze Age. One notable example comes from between the third and fourth centuries BC, when inhabitants of the Roman colony of Elea (later known as Velia) constructed a street featuring a small gutter designed for drainage. This represents just one of many early instances of grate use in ancient infrastructure. Grates also played a significant role in the development of home heating; by the 11th century, they were being used in fireplaces, proving especially effective for holding coal during combustion.
Early grate designs, including wall grates, were commonly made from durable metals like iron or steel. While some followed basic square or rectangular forms, others featured arched or circular shapes, and certain models were built on a large scale. In modern times, grates are more frequently manufactured using materials such as thermoplastic or aluminum bars, which are less expensive and easier to produce. Contemporary designs often include angled openings or adjustable pins to allow for directional airflow. Despite these advancements, antique gratings remain highly valued by collectors and those involved in historic building preservation. Many also seek them out purely for their unique visual charm.
Today’s grates are far more diverse than their historical counterparts—not only in terms of materials but also in design and function. Modern applications extend well beyond traditional uses, and engineers continue to develop new forms to enhance performance, durability, and environmental sustainability.
Advantages of Gratings
Gratings offer numerous advantages across a variety of applications. When installed on floors, they enhance traction and tread, significantly improving workplace safety. They are particularly effective in meeting safety regulations in areas prone to fluid or lubrication leaks, as well as on stairs and elevated walkways in factories or warehouses. In addition to providing slip-resistant surfaces for foot traffic, gratings also offer added grip for vehicles like forklifts and other types of machinery. Beyond safety, they contribute to the efficiency of processes such as drainage, allowing liquids to pass through easily and keeping surfaces dry.
The manufacturing of gratings also brings several benefits. It allows for exceptional design flexibility, accommodates a broad selection of materials, and supports production in a wide range of sizes and thicknesses, making it easier to tailor solutions to specific industrial needs.
Design of Gratings
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Production Process
Grate manufacturing involves several methods depending on the material and intended use. For metal gratings, common techniques include metal plate expansion, perforation, and welding. In the expansion process, manufacturers slit and stretch metal to specific dimensions, a method favored for its low material waste. Perforation involves the use of a punching press to create precise hole patterns in metal sheets. To enhance durability, metal gratings are often treated with hot dip galvanization, in which they are coated in zinc oxide. This protective layer shields the metal from corrosion, oxidation, and other environmental damage that could reduce its lifespan.
Plastic and fiberglass (FRP) gratings are typically made using molding or pultrusion. During molding, materials are manually layered to control thickness and dimensions, then placed in a mold for curing. Once cured, the grates are ready for installation. This method is especially popular because fiberglass molds are reusable and easily cleaned. Pultrusion, similar to extrusion, differs in that impregnated bar resins are pulled—rather than pushed—through a die. This automated process is used primarily for making pultruded fiberglass grates, offering high consistency and minimal material waste, while accommodating a wide range of sizes and configurations.
Alternatively, both metal bar gratings and fiberglass bar gratings may be assembled using welding, swaging, or riveting. These methods create grid-like rectangular configurations by permanently fusing each bearing bar with a corresponding cross bar, ensuring the rigidity and structural integrity needed for walkways, platforms, trench covers, and safety barriers.
Material Design
Gratings can be fabricated from a variety of materials including aluminum, iron, carbon steel, welded steel, alloy stainless steel, fiberglass, and reinforced plastic. Metal grates—typically made from aluminum, carbon steel, or stainless steel—are chosen for their strength and are commonly used for surface filtration, load-bearing, and slip-resistant applications. Fiberglass and plastic gratings, on the other hand, are lighter alternatives used in applications such as floor panels, drainage systems, and architectural features. These materials are favored for their ease of installation, resistance to rust, slip resistance, and fire-retardant properties.
Design Considerations
Grates are manufactured in various thicknesses, bar dimensions, and grip patterns based on the environmental conditions and required load capacity. Floor gratings, in particular, come in a variety of opening patterns—such as diamond or oval shapes—each offering unique strength characteristics. While aesthetics may influence design, especially for architectural uses, structural integrity and functionality are the top priorities. The percentage of open area in a grating directly affects the amount of light, air, sound, and water that can pass through.
The most robust floor gratings are typically constructed from welded or pressure-locked interlocking bars. For customized applications, manufacturers can cast grates to accommodate complex designs. This allows for virtually unlimited customization, including specifications for opening shapes and sizes, bar spacing, bar strength-to-weight ratios, bar thicknesses, and overall dimensions.
Grating Types
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Architectural Grates
Metal or fiberglass-reinforced plastic lattices integrated into building designs for both functional and aesthetic purposes, serving roles in ventilation, drainage, or visual enhancement.
Aluminum Grating
A framework constructed from alloyed aluminum bars, sheets, or meshes to create a porous grid. Common in industrial, commercial, and domestic settings, aluminum grating is prized for its excellent corrosion resistance, lightweight properties, and high strength-to-weight ratio.
Covered Grating
A molded fiberglass flooring solution that combines a slip-resistant surface plate with molded grating underneath, offering durability and enhanced safety.
Aluminum Grating
Critical elements of drainage systems, these grates allow fluid to pass through while capturing debris that could clog or damage the piping infrastructure.
Expanded Metal Grating
Lightweight, cost-effective, and durable, this type of grating provides traction without requiring special installation tools. It features openings ranging from 3/16" to 2".
Floor Gratings
A broad category that includes any type of grating used for flooring or as an enhancement to improve safety, grip, or load capacity in walking and working surfaces.
Galvanized Grating
Gratings coated with zinc to increase corrosion resistance and durability in environments where exposure to moisture, chemicals, or heavy use is common.
Metal Grates
The industry standard for floor gratings, typically made from stainless steel or iron. Aluminum variants are also used in applications with lighter traffic or weight requirements.
Perforated Metal
A fabricated metal sheet punched with holes in various patterns and sizes using a press. Often combined with expanded metal in flooring applications for added texture and functionality.
Plastic Grating
While never made from pure plastic, these gratings are reinforced with fiberglass to increase strength and durability in various settings.
Pressure Locked Grating
Highly versatile, pressure locked grating accommodates a wide range of load-bearing bar spacing and can be efficiently produced in small batches.
Stainless Steel Grates
Manufactured from alloyed steel bars, sheets, or meshes, stainless steel grates resist rust, corrosion, and staining, making them ideal for environments with harsh chemicals or volatile fluids and gases.
Welded Grating
Created by electrically fusing cross bars to load-bearing steel bars, resulting in a strong, durable grid structure widely used in flooring and industrial applications.
Bar Grate
Known for its strength and resilience, bar grating is most commonly made from metal. It features vertical load-bearing bars evenly spaced and joined by horizontal cross bars in a rectangular grid. These grates are frequently used for walkways, platforms, mezzanine decking, stair treads, and more.
Stair Tread
Typically made from perforated or expanded metal, stair treads include serrated teeth, cut-out holes, or textured surfaces to prevent slips and resist debris buildup. They serve as stair covers, ladder covers, or as the structural components of stairs and ladders.
Trench Gate
Long, narrow bar grating covers placed over street and sidewalk drains to allow pedestrian traffic while facilitating water drainage. These gates come in a range of designs and may either rest on the drain or be securely bolted in place.
Fiberglass Grate (FRP Grate)
The strongest type of plastic grating , reinforced with glass fibers for added strength, corrosion resistance, and heat tolerance. Commonly used for floors, stairs, and enclosure systems in corrosive or high-heat environments.
Steel Grate
Known for its strength and reliability, steel grating suits a wide range of applications. For added protection in corrosive environments, galvanized steel options are also available.
Grating Applications
Manufacturers produce gratings for a wide range of critical building and construction applications, including enhanced traction and tread, efficient drainage, separation, ventilation and airflow, and sun shading. Gratings are also commonly used as louvers, ornamental or decorative screens, fencing, handrails, perforated walkways, and pedestrian covers for narrow sewers and drains, allowing safe passage over these openings.
Due to their essential role in promoting safety in both workplace and residential environments, gratings are in high demand across a variety of industries. These include food and beverage, building construction, industrial manufacturing, HVAC, mining, water treatment, plumbing, and hygiene sectors.
Grating Installation
While every installation scenario is unique, there are a few fundamental guidelines to follow when installing grates.
Ensure the grating is installed with the cross rods facing upward. This orientation is critical for meeting strength requirements.
For maximum structural integrity, use metal materials for all grating supports.
Provide a minimum bearing of 1 inch for bearing bar depths up to 2-1/4 inches. For bearing bar depths of 2-1/2 inches or more, a minimum bearing of 2 inches should be maintained.
Adhere to all specified dimensional tolerances to maintain proper clearances.
When making cutouts for circular obstructions, ensure the opening is at least 2 inches larger in diameter than the obstruction itself.
Standards and Specifications for Grates
One of the ways consumers can assess grating compatibility and quality is by checking its ASTM grade. ASTM International has established safety and quality standards for nearly all materials and products, including various types of gratings. For example, ASTM F 3059-15 outlines standards for FRP gratings commonly used in marine construction and shipbuilding. These standards also cover the materials and manufacturing processes involved, such as steel quality, hot-dipping, and galvanization. It is strongly recommended that you 1) confirm your product has been evaluated and assigned an ASTM quality standard grade, and 2) ensure that its grade aligns with your specific performance and application requirements.
Things to Consider When Purchasing Gratings
To ensure you get the best grating for your application—one that offers the right balance of strength, durability, stability, and corrosion resistance—it’s essential to work with an experienced grating supplier. A knowledgeable supplier can help you navigate the many material options, patterns, and manufacturing processes involved in grating production.
Not sure where to begin? No problem! IQS has put together a list of top-rated grating manufacturers, all of whom are known for their reliability and dedication. Start by browsing their websites to identify the companies that offer services most aligned with your needs. Then, reach out to three or four of them. Be sure to ask each supplier the same key questions regarding lead times, delivery options, budget constraints, standard product specifications, and available customization. Once you’ve gathered responses, compare them closely and choose the manufacturer that you feel offers the strongest combination of service, support, and value. The right partner is out there—and with a bit of research, you’ll find the one that fits your project best.
Proper Care for Gratings
To keep your grating products functioning effectively and in good condition, regular cleaning is strongly recommended. Slip-resistant gratings, in particular, require frequent cleaning to prevent the buildup of residue or debris that can diminish their textured, non-slip surface.
Most grates can be cleaned using standard cleaning products, though the appropriate solution varies depending on the material. For example, grease and oil can often be removed with organic enzyme or alkaline-based cleaners. However, while these agents may work well on some steels, they can cause discoloration—such as blackening—on others, like stainless steel. If you notice rust on a stainless steel grate, it can typically be treated with diluted muriatic acid, using a solution no stronger than one part acid to one part water. For specific recommendations based on your grating type and material, consult your supplier.
Depending on your grate design, debris can often be removed using tools like soft-bristle brushes or compressed air cans. For heavier buildup, such as sludge or grime, more intensive methods like power washing or the use of a stiff bristle brush may be necessary to restore the grate’s performance and safety.
Grate Accessories
To ensure your grating system is fully prepared for any application, make sure you have the necessary accessories. These may include components such as fasteners, locks, bolts, hold down clamps, hold down clips, anchor plates, washers, butterfly clips, and channel connectors. To determine which accessories best suit your system and requirements, consult your grating supplier for expert guidance.
Grating Terms
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Anchor
The component used to secure the grating to its supporting structure.
Bearing Bars
The primary load-bearing elements of a grating, made from steel strip, slit sheet, or rolled/extruded aluminum, running parallel to the span direction.
Bond
The point where two strands intersect in the grating pattern.
Carriers
Flat bars or angles welded to the grating panel and the nosing of a stair tread to provide structural support.
Cross Bars
Bars that run perpendicular to the bearing bars, connecting them. These are typically welded, forged, or mechanically locked at the points of intersection.
Cutout
A section of the grating that has been removed to accommodate the passage of pipes, ducts, columns, or similar obstructions.
Grating
An open-grid structure composed of metal bars, with bearing bars aligned in one direction and spaced by cross bars running perpendicular or by connecting bars between them.
Grating Frame
A metal frame that houses floor grating and serves as an anchoring structure for floor installations.
Grating Tread
The walking surface of a step, made from a grating material.
Hinged Panels
Grating sections that are hinged to their supports or to adjacent grating parts, allowing them to open or move.
Kick Plate
A flat bar mounted vertically along the outer edge of a grating, projecting above its surface to form a raised lip or curb.
Nosing
An L-shaped component forming the front edge of a stair tread or the leading edge of a stairway grating section.
Reticuline Bar
A sinuous connecting bar running between adjacent bearing bars, alternately touching and being riveted to each one.
Rivet Centers
The distance measured from the center of one rivet to the center of the next along a bearing bar.
Reversible Grating
Grating designed for installation with either side facing up.
Span of Grating
The distance between two support points for the grating.
Straight Cut
The portion of a grating edge or cutout that follows a straight line.
Trim Band
A non-load-bearing band added mainly for visual or aesthetic purposes.
Width
The total measurement of a grating panel taken perpendicular to the direction of the bearing bars.
