Engineering Reference

Expanded Metal Specifications

Technical specification reference for expanded metal. Compare short and long way design dimensions, strand widths, sheet tolerances, and load ratings across standard and flattened configurations.

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Specification Highlights

ASTM / EMMA

Mesh Patterns

Standard diamond, flattened, and architectural profiles

Gauge Range

18-ga light duty up to 9-ga heavy structural grating

Open Area

Calculated SWD x LWD dimensions with 35% to 80% free airflow

Standards Compliant

Fabricated to ASTM F1267 and EMMA 557 industrial standards

Standard & Flattened SheetsMaterial grades →
Technical Guide

Expanded metal specification standards

Understanding core dimensional callouts ensures accurate structural sizing, proper diamond orientation, and exact fit for architectural, industrial, and filtration applications.

SWD
Short way of design
Primary dimension

The dimension measured from the center of the bond on one side to the center of the bond on the opposite side across the short diagonal of the diamond opening.

Application note:Defines the vertical diamond span when ordered in standard orientation.
LWD
Long way of design
Primary dimension

The dimension measured across the long diagonal of the diamond opening from bond center to bond center.

Application note:Oriented parallel to the length of standard manufacturing rolls and coils.
Strand Width
Strand width
Material geometry

The width of the metal strand feeding into the slit-and-stretch tooling to form each side of the diamond mesh.

Application note:Determines physical rigidity, load capacity, and weight per square foot.
Strand Thickness
Strand thickness
Gauge specification

The nominal thickness of the base metal sheet or coil prior to the slitting and expanding manufacturing cycle.

Application note:Matches base mill gauge tolerances across carbon steel, stainless, and aluminum.
Open Area
Open area percentage
Performance metric

The proportion of unobstructed open space in the diamond pattern relative to the total surface area.

Application note:Critical for airflow calculations, light transmission, acoustic control, and drainage.
Sheet Size
Standard sheet dimensions
Stock & custom cuts

Standard stock sheet sizes (such as 4 ft × 8 ft, 4 ft × 10 ft, and 5 ft × 10 ft) or sheared-to-dimension panels with closed or random borders.

Application note:Supplied flattened (smooth surface) or standard raised (traction profile).
Mesh Geometry Reference

How dimensions interact on standard panels

Expanded metal is produced by simultaneous slitting and stretching operations with zero material loss. The final open area and rigidity depend on the ratio of strand width to diamond opening size.

SWD × LWD defines aperture geometry and orientation.
Strand width + thickness controls structural deflection limits.
Open area % sets fluid flow, ventilation, and shadow casting.

Key engineering guidelines

Ordering convention

Always state SWD before LWD (for example, 3/4" #9 SWD × LWD) to ensure proper diamond orientation across your support framework.

Standard vs. Flattened

Standard expanded metal features raised, angled strands for slip resistance, whereas cold-rolled flattened metal provides a smooth single-plane finish.

Edge options

Panels can be supplied with random shear cuts for welding into frames or balanced bond-sheared borders for clean architectural edges.

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