Expanded Metal: History, Design, Architectural Applications and Safety

Expanded metal is an open metal product manufactured by cutting a repeated pattern of slits into a solid sheet and expanding the sheet so that the slits form connected openings. The openings are commonly diamond-shaped, although hexagonal, elongated and decorative patterns are also available. The remaining material forms continuous strands and bonds rather than separately woven or welded wires.

A representative customer, whom we will call Emma, needed expanded metal for a parking-garage facade, maintenance walkway and machinery enclosure. Her original drawing showed only a diamond pattern and a nominal sheet thickness. Suppliers proposed different apertures, strand widths, raised profiles, finishes and panel orientations, making the quotations technically incomparable.

We helped Emma divide the project into three different engineering problems. The facade required wind resistance, controlled visibility, ventilation, coating durability and visual consistency. The walkway required verified load performance, secure supports, suitable surface characteristics and safe edges. The machinery enclosure required hazard separation, rigidity, controlled openings and reliable attachment to its frame.

The real pain was that products with the same general name had different geometry and performance. The counter-intuitive point was that the most open or lightest mesh was not automatically the most economical choice because it could require heavier frames and closer supports. The industry explanation was that expanded metal is direction-dependent, so performance changes with the pattern, material, profile, orientation and installed boundary conditions. The memorable conclusion was that a diamond shape is not a complete technical specification. The action direction was to approve measurable geometry, panel construction, finish and application requirements before comparing price.

1. What Expanded Metal Is

Expanded metal is produced from one metal sheet rather than assembled from separate wires.

During manufacturing, expanding dies create alternating slits in the sheet. The material is displaced and stretched, causing the slits to open while leaving connected strands between them. Wider areas where strands meet are normally described as bonds.

This process creates a product with continuous strands and bonds, no woven wire intersections, no weld at every opening, direction-dependent geometry, a combination of solid metal and open area and compatibility with cutting, folding and framing.

The current EMMA 557-25 Standards for Expanded Metal, published through the Expanded Metal Manufacturers Association and NAAMM, covers terminology, manufacturing processes, product selection and manufacturing tolerances. It provides a more reliable technical basis than describing a product only as “diamond expanded mesh.”

Expanded metal is sometimes described as having no material waste because each opening is created by stretching rather than punching out an individual slug. That statement requires qualification.

The expanding operation can avoid the aperture-by-aperture slug waste associated with conventional perforating. Finished production may still create scrap from edge trimming, machine setup, defective material, sample production, panel cutting, irregular panel shapes, frame fabrication and drawing revisions.

It is more accurate to say that expanding can use the original sheet efficiently, while the total material yield depends on the complete manufacturing plan.

2. Why Expanded Metal Does Not Unravel

Woven wire mesh is assembled from separate wires passing over and under each other. When woven mesh is cut, individual wires may move or require edge stabilization.

Expanded metal behaves differently because the strands and bonds remain portions of the original sheet. Cutting a panel does not cause it to unravel like a woven fabric.

However, this continuity does not mean every cut panel is immediately safe or ready to install.

Cutting may leave sharp strand ends, partial diamonds, unsupported bonds, irregular borders, weak fixing locations and inconsistent visual edges.

Depending on the application, the panel may require deburring, controlled bond shearing, edge banding, welded frames, folded returns, protective channels or reinforced fixing zones.

Material continuity is an advantage, but finished-edge design remains essential.

3. The History of Expanded Metal

Expanded metal developed as an industrial method for converting sheet metal into an open but connected structure.

John French Golding is widely associated with the invention and early patent development of expanded sheet metal. The Expanded Metal Company traces its industrial heritage to Golding’s work and states that his expanded-metal innovation received a patent in 1884. The company’s later manufacturing history became closely associated with Hartlepool in the United Kingdom. Its current product guide describes an industrial heritage dating to 1889. The Expanded Metal Company history.

Accessible United States patent records also document Golding’s later improvements to methods and machines for expanding sheet metal. These records show that the essential concept involved creating staggered slits and opening the cut areas into an interconnected metal structure.

Early expanded-metal products found uses in building reinforcement, metal lath, fencing, industrial guards, platforms, screens and construction components.

The manufacturing process later developed into a wide range of industrial, security and architectural products.

4. Raised Expanded Metal

Raised expanded metal retains the three-dimensional profile created during expansion.

The strands are inclined rather than positioned entirely within one flat plane. The resulting product has a measurable profile depth and a textured surface.

Raised expanded metal may provide a pronounced industrial appearance, open drainage paths, surface texture, greater profile depth and different directional stiffness from flattened mesh.

Common applications include maintenance walkways, catwalks, stair treads, drainage covers, machinery guards, security panels and equipment enclosures.

It is inaccurate to state that every raised mesh is automatically non-slip.

Traction can be affected by strand geometry, material, surface finish, water, oil, dust, mud, footwear, direction of travel, surface wear, slope and cleaning practices.

A raised surface may contribute to traction, but safety-related claims should be supported by applicable testing and project requirements.

5. Flattened Expanded Metal

Flattened expanded metal begins as raised mesh and is then passed through levelling rollers.

Rolling reduces the raised profile and produces a smoother surface. The process may also alter overall thickness, sheet width, sheet length, aperture shape, strand angle, flatness, directional stiffness and surface appearance.

Flattened expanded metal is commonly considered for facade panels, ceiling systems, cabinet inserts, ventilation grilles, speaker covers, decorative screens, retail fixtures, filter-support panels and hand-contact guards.

Flattening does not guarantee that every edge becomes safe. A flattened sheet can still produce sharp strand ends when it is cut.

Drawings should state whether the specified dimensions apply before or after flattening.

6. Mesh Shapes and Pattern Geometry

Diamond-shaped apertures are common because they are compatible with continuous staggered slitting and expansion.

Expanded metal can also be produced with elongated diamonds, hexagonal openings, scale-like patterns, decorative shapes, large architectural apertures and custom directional patterns.

The geometry influences both appearance and physical behavior.

Important variables include short-way pitch, long-way pitch, clear aperture, strand width, material thickness, bond dimensions, raised profile depth, pattern direction and degree of expansion.

It is not scientifically reliable to claim that one diamond angle is always strongest.

Mechanical behavior depends on the complete combination of material grade, sheet thickness, strand dimensions, bond geometry, pattern angle, panel dimensions, direction of loading, supports, frames, fixings and raised or flattened condition.

A pattern that performs well during axial compression testing may not provide the best result under bending, impact, wind or pedestrian loading.

7. SWD, LWD, Aperture and Strand Width

Short Way of Design

The short way of design, often abbreviated SWD, identifies the shorter repeating dimension of the pattern.

Some suppliers use SWM, meaning short way of mesh. Because terminology varies, drawings should define the abbreviation.

Long Way of Design

The long way of design, often abbreviated LWD, identifies the longer repeating dimension.

Some suppliers use LWM, meaning long way of mesh.

The long-way direction should be identified on finished-panel drawings because rotating the panel may affect deflection, support behavior, frame arrangement, panel joints, visual pattern and installation sequence.

Strand Width

Strand width is the width of the metal between adjacent openings.

A wider strand normally retains more metal in the pattern, but it cannot independently predict strength, weight or open area.

Material Thickness

Material thickness normally refers to the thickness of the original sheet.

It should not be confused with the total height of a raised mesh profile.

Clear Aperture

The aperture is the clear opening between strands.

It is different from pattern pitch and should be specified separately when the project must control the passage of objects, limbs, particles or debris.

8. Expanded Metal Is Direction-Dependent

Expanded metal is anisotropic, meaning its properties can differ according to direction.

This is important because the sheet is not mechanically identical along the short and long pattern directions.

A supplier should not use a universal rule such as “the long way must always cross the span” without reference to the exact product and load data.

The correct process is to identify the exact mesh style, define the supported span, show the proposed pattern orientation, define the applied load, review the frame and fixing arrangement, check verified load and deflection data and record the approved orientation.

Our factory can identify pattern direction on drawings, labels and packing lists. The responsible engineer must verify the structural suitability of the complete installed panel.

9. Strength and Weight Claims Require a Fair Comparison

Expanded metal is sometimes described as stronger than an equivalent weight of woven wire mesh or even stronger than solid sheet.

Such statements are incomplete without a defined test method.

Expanded metal can provide useful rigidity because it originates from sheet material, its strands remain connected, it has a three-dimensional profile when raised and its pattern can distribute load through multiple strands.

But actual performance depends on the comparison product and the loading condition.

A valid comparison must define material, yield strength, total weight, panel dimensions, support conditions, load direction, deflection limit, failure criterion, frame construction and fixing method.

Expanded metal may be more rigid than a lightweight woven mesh in one application. A heavy woven mesh, bar grating or reinforced solid sheet may perform better in another.

The correct question is not “Which product is strongest?” It is “Which defined product meets the required performance with acceptable weight, cost and service life?”

10. Open Area, Airflow, Water and Light

The openings in expanded metal allow air, water and light to pass through the panel.

This makes it useful for ventilation covers, plant-room screens, drainage panels, sunscreens, equipment enclosures, parking-garage facades and protective screens.

Open area is the percentage of the projected panel area occupied by openings.

It is an important design parameter, but open area alone does not determine airflow.

Actual airflow and pressure loss can also depend on aperture shape, strand angle, mesh depth, air velocity, flow direction, frames, filters, louvres, multiple mesh layers and dust accumulation.

Similarly, visible transparency depends on more than open-area percentage.

It can change with viewing angle, viewing distance, pattern orientation, lighting, coating colour, background and objects behind the screen.

For architectural projects, a full-size mock-up is usually more informative than a small sample.

11. Fences, Grates and Protective Barriers

Expanded metal is widely used where a project requires an open mechanical barrier.

Common applications include perimeter fencing, security panels, warehouse partitions, storage cages, window guards, equipment barriers, drainage covers and protective grilles.

The connected pattern can resist wire-by-wire separation, but security performance depends on the complete system.

Important factors include material thickness, strand width, aperture, panel height, frame spacing, fixings, ground clearance, cutting resistance, climb resistance and corrosion protection.

An expanded-metal sheet installed inside a weak frame cannot provide a high-security barrier merely because the mesh itself appears robust.

12. Metal Lath and Construction Support

Expanded metal has a long history as a support or reinforcement layer for plaster, render and stucco systems.

Metal lath provides a mechanically keyed surface. Applied material passes partly through the openings and forms a connection around the strands.

The performance of a lath system depends on lath type, material and coating, orientation, support spacing, fastening, overlaps, substrate, render or plaster system and environmental exposure.

Expanded-metal lath should therefore be selected as part of an approved wall or ceiling assembly rather than as an isolated sheet product.

13. Art, Sculpture and Formed Surfaces

Artists and fabricators use expanded metal as an armature for three-dimensional forms.

Its open structure can support plaster, clay, render, composite materials, decorative coatings and lightweight sculptural skins.

Thin expanded metal can be bent into compound forms more easily than heavy rigid panels. Heavier patterns may require rolling, press forming or framed construction.

Artistic applications still require attention to sharp edges, structural support, corrosion, public contact, fire performance, coating compatibility and outdoor exposure.

A visually lightweight sculpture may still require substantial internal framing.

14. Expanded Metal in Contemporary Architecture

Expanded metal is used as an exposed architectural material on building facades, secondary skins, parking structures, schools, museums, equipment screens, ceilings, interior cladding, retail installations and signage.

The New Museum’s SANAA-designed building in New York is a well-documented architectural example. The museum describes the building as a stack of offset boxes clad in a seamless anodized expanded-aluminium mesh selected to give the building a delicate and softly shimmering exterior skin. The original SANAA building opened in 2007, not 2021. New Museum archive.

This corrects the claim that architectural interest in expanded metal began when the New Museum started winning awards for its facade in 2021.

Expanded metal had architectural uses long before that date. The New Museum is significant because it demonstrated how an industrial material could create a visually light, continuous and distinctive cultural-building facade.

15. Why Architectural Transparency Changes

An architectural mesh panel can appear open from one direction and relatively solid from another.

The effect is influenced by aperture proportions, strand width, strand angle, raised profile, panel orientation, viewing height, sun position, interior lighting, exterior lighting, coating reflectivity and background colour.

This enables designers to create facades that change appearance throughout the day.

It also creates specification risk.

A sample viewed horizontally under office lighting may not represent a panel installed vertically several metres above ground. Full-size exterior mock-ups allow the design team to review transparency, colour, pattern alignment, reflections, shadow, nighttime appearance, fixing visibility and panel joints.

16. Expanded Metal as a Sunshade

Expanded metal can function as part of an exterior shading system by intercepting a portion of direct solar radiation before it reaches glazing or the building envelope.

The amount of shading depends on solar orientation, aperture geometry, panel depth, distance from the glazing, pattern angle, time of day, season, geographic location, coating reflectance and surrounding obstructions.

The US Department of Energy notes that solar heat gain can be a major contributor to building cooling loads and that exterior shading can reduce that load. It also emphasizes that shading must be optimized to balance cooling reduction, useful winter heat and daylight. US Department of Energy exterior shading research.

It is therefore too broad to claim that any expanded-metal facade automatically reduces energy consumption and carbon emissions.

A reliable project should evaluate solar exposure, daylight, glare, cooling load, winter heating, interior views, local climate, embodied impacts and maintenance.

Expanded metal is the physical shading component. Building-energy performance depends on the complete facade design.

17. Parking-Garage and Equipment Screens

Expanded metal is particularly useful for open parking structures and equipment screens because it can combine natural ventilation potential, visual screening, daylight, impact resistance, security and architectural identity.

The design must still address required free area, wind load, panel deflection, fixing loads, vehicle impact zones, fire and smoke requirements, drainage, corrosion, cleaning and access for repairs.

A highly closed-looking pattern may restrict ventilation. A very open pattern may provide insufficient privacy or object containment.

The correct design balances these competing requirements.

18. Walkways, Catwalks and Drainage Covers

Raised expanded metal and expanded-metal grating can be used for selected pedestrian surfaces.

Potential applications include maintenance platforms, catwalks, stair treads, service ramps, stage floors and drainage covers.

Not every expanded-metal sheet is a load-rated grating.

The project must define distributed load, concentrated load, support span, allowable deflection, pattern orientation, bearing, panel joints, frames, fasteners, anti-uplift restraint, surface conditions, edge treatment and inspection procedures.

Exposed raised strands may provide surface texture, but texture alone does not prove that the finished walkway meets a required slip classification.

A qualified design should use load data or testing for the exact product, orientation and support arrangement.

19. Machinery Guards

Expanded metal is frequently used for belt guards, pulley guards, fan guards, conveyor enclosures, machine-perimeter panels, drive-system covers and lamp cages.

It can preserve airflow and visibility while creating physical separation.

Guard safety cannot be determined by the aperture alone.

The complete guard must consider distance from the hazard, reach through openings, reach over and under the guard, rigidity, impact, frame strength, fixing security, access doors, interlocking, removal procedure, bottom gaps, ejected parts and sharp edges.

OSHA’s machine-guarding guidance states that safeguards should prevent contact, resist tampering and avoid creating new hazards. Its safety guidance specifically notes that guard edges should be rolled or secured in a way that eliminates sharp edges. OSHA machine-guarding standards.

Our factory can control the mesh, frame, welds, panel dimensions and edge condition. The machine designer or responsible safety professional must evaluate the complete guarding arrangement.

20. Sharp Edges and Safe Handling

Freshly cut expanded metal can expose numerous sharp strand ends.

Workers may be at risk during cutting, lifting, turning panels, welding, framing, coating, packing, unpacking and installation.

Depending on the risk assessment, controls may include cut-resistant gloves, suitable sleeves, eye protection, controlled lifting, edge protectors, banding, deburring, framing and protected packing.

Personal protective equipment is not a substitute for designing safer finished edges.

A frequently handled maintenance panel should generally receive more controlled edge treatment than a panel permanently enclosed inside a frame.

21. Why Edge Treatment Must Be Specified

An instruction such as “cut to size” is incomplete.

The customer should define whether each edge will be open, framed, banded, folded, hidden in a channel, joined to another panel, supported or frequently handled.

Our factory reviews the function of each edge before selecting the cutting and finishing method.

Edge treatment affects safety, appearance, panel stiffness, weld quality, coating continuity, fixing reliability, installation time and packing protection.

A clean architectural border may require different processing from a concealed industrial edge.

22. What Our Factory Confirms Before Production

Before manufacturing an expanded-metal order, we normally confirm application, material and grade, raised or flattened condition, short-way dimension, long-way dimension, clear aperture, strand width, original material thickness, overall profile depth where relevant, open area, pattern orientation, finished panel size, support or frame arrangement, edge treatment, folds and fixing holes, welding requirements, surface finish, dimensional tolerances, flatness requirements, panel identification and packing sequence.

When information conflicts, we return a marked drawing for confirmation rather than selecting an interpretation without customer approval.

23. Factory Inspection and Working Style

Depending on the project, quality control may include raw-material verification, material-thickness measurement, pattern-dimension inspection, strand-width measurement, aperture inspection, profile-depth inspection, panel-size measurement, squareness inspection, flatness inspection, edge inspection, frame inspection, weld inspection, coating inspection, visual sample comparison, panel-label verification and packing inspection.

Architectural panels can be compared with an approved mock-up or production sample.

Installation packages can be labelled according to elevation, zone or drawing position.

Our working principle is: Clarify before production, measure before release and protect before shipment.

This may require more technical communication before manufacturing, but it reduces the probability of producing an entire order from an incomplete drawing.

24. A Scientific Selection Process

Step 1: Define the Function

Identify whether the expanded metal will be used for facade cladding, shading, ventilation, security, machinery guarding, walkways, drainage, lath, art or sculpture.

Step 2: Define the Required Performance

Confirm structural loads, deflection, airflow, visibility, shading, object retention, impact, security, surface contact and maintenance.

Step 3: Choose Raised or Flattened Mesh

Base the decision on profile depth, texture, handling, cleaning, appearance, forming, framing and verified performance.

Step 4: Define the Geometry

Specify short-way dimension, long-way dimension, clear aperture, strand width, material thickness, open area and pattern orientation.

Step 5: Select the Material and Finish

Consider interior or exterior use, coastal exposure, chemicals, moisture, wash-down, temperature, corrosion, architectural colour and maintenance.

Step 6: Design the Finished Panel

Confirm panel dimensions, frames, folds, edges, fixings, supports, tolerances, identification and packing.

Step 7: Verify the Installed System

Use applicable calculations, testing, standards or qualified professional review when the mesh is part of a pedestrian surface, machinery guard, structural facade, security barrier or safety-critical enclosure.

Conclusion

Expanded metal is an open sheet product created by slitting and expanding a continuous piece of metal.

Its continuity means that it does not unravel in the same way as woven wire mesh. That characteristic does not prove that every expanded-metal product is stronger than every wire mesh, solid sheet or grating product.

Its geometry can distribute loads and create useful rigidity, but performance depends on the complete combination of material, thickness, strand width, aperture, bond geometry, raised or flattened condition, pattern orientation, panel dimensions, supports, frames, fixings and finish.

Its openings can admit air, water and light, but open-area percentage alone does not determine airflow, drainage, visibility or energy performance.

Its textured edges may support traction, but they can also create handling hazards. Edge treatment and engineering verification must therefore form part of the product specification.

Emma’s project succeeded after the applications were separated. The facade was developed around wind, transparency, coating, joints and shading. The walkway was evaluated according to loads, span, fixing and surface conditions. The machinery enclosure was designed around hazard distance, rigidity, secure attachment and safe edges.

The next article will examine How Expanded Metal Facades Control Transparency, Shade and Ventilation, including the effects of aperture geometry, orientation, lighting, panel depth, open area and support design.

This article helps customers solve the problem of relying on unsupported expanded-metal claims and provides the benefits of more accurate specifications, more defensible engineering decisions, safer handling and fewer manufacturing or installation errors.

30 SEO Keyword Groups

#ExpandedMetal,#ExpandedMetalMesh,#ExpandedSheetMetal,#DiamondMesh,#HexagonalExpandedMetal,#RaisedExpandedMetal,#FlattenedExpandedMetal,#StandardExpandedMetal,#ExpandedMetalHistory,#JohnFrenchGolding,#ExpandedMetalDesign,#ExpandedMetalStrand,#ExpandedMetalAperture,#ExpandedMetalOpenArea,#ExpandedMetalFacade,#ArchitecturalMetalMesh,#BuildingSunshade,#ParkingGarageScreen,#EquipmentScreen,#ExpandedMetalFence,#SecurityMeshPanel,#ExpandedMetalWalkway,#ExpandedMetalCatwalk,#DrainageCoverMesh,#MachineGuardMesh,#ExpandedMetalLath,#SculptureArmature,#CustomExpandedMetal,#ExpandedMetalSafety,#ExpandedMetalManufacturer

Contact Jintong Perforated Metal

Telephone: +86 18520485059
Email: [email protected]
Instagram: instagram.com/jintongperforatedmetal
WhatsApp: https://shorturl.at/jdI6P
LinkedIn: https://www.linkedin.com/in/andy-liu-36a033355/
YouTube: youtube.com/@Jintong-n7d
Website: perforatedmetalpanel.com