# Expanded metal

Slit-and-stretched sheet: raised and flattened forms, pitch versus aperture, orientation, ordering dimensions and bounded load-data interpretation.

Reviewed: 2026-11-01

Tags: materials, stock-forms, sheet-metal, mesh

## What the stock form means

McNICHOLS item **560N151648**, styled **1-1/2 in No. 16 Flattened**, gives **SWD/LWD pitch of 1.330/3.150 in** and **SWO/LWO clear opening of 1.092/2.750 in**. Its long opening runs parallel to sheet length. Specify the opening and orientation separately from the style name. [McNICHOLS exact item record](https://www.mcnichols.com/expanded-metal/flattened/carbon-steel-cs-560n1516?cId=&rbl=)

Expanded metal starts as sheet that is slit and stretched into an interconnected mesh. The Expanded Metal Company explains that the initial raised form has strands inclined out of the sheet plane; flattening subsequently changes the profile and thickness. Raised and flattened products therefore need separate dimensional descriptions, even when sold under similar nominal pattern names. [Expanded Metal Company measuring guide](https://www.expandedmetalcompany.com/news/post/how-to-measure-and-specify-expanded-metal.html)

The stock form does not identify the base alloy, grade, coating or load capacity. McNICHOLS separates standard/raised, flattened, grating, catwalk-grating and designer products in its ordering guide. Selecting a light screening sheet is a different task from specifying a supported walking surface. A catalogue application such as “machine guard” is not proof that an arbitrary opening and installation satisfy the particular guarding requirement. [McNICHOLS specifying and ordering](https://assets.mcnichols.com/content/dam/mcnichols/resources/PDF/EM-Specify-Order.pdf)

## Read the manufacturer's dimension convention

A complete description distinguishes repeating pattern dimensions from the unobstructed hole:

| Field | Meaning and ordering consequence |
| --- | --- |
| Design size or pitch | Repeating distance across mesh junctions; do not treat it as clear aperture |
| Clear opening/aperture | Unobstructed opening measured by the supplier's drawing |
| Strand width | Width of the strip forming the mesh |
| Strand thickness | Metal thickness, with processing stage identified |
| Overall thickness/depth | Envelope needed for mounting or clearance |
| Sheet dimensions and orientation | Finished panel envelope plus the diamond direction relative to its edges |

The Expanded Metal Company's P00927 sheet explicitly measures raised-mesh **LWP and SWP between knuckle centers**. It distinguishes these from strand width and thickness and warns that dimensions and weights are approximate. Do not translate abbreviations across catalogues without checking the drawing. [P00927 measurement notes](https://www.expandedmetalcompany.com/media/productattach/p/0/P00927_raised_V1.1.pdf)

For example, McNICHOLS distinguishes SWD/LWD design sizes from SWO/LWO opening sizes on the same product record. “Short way” is not enough information unless the field states whether it is a pitch or an opening. [McNICHOLS flattened-sheet dimensional record](https://www.mcnichols.com/expanded-metal/flattened/carbon-steel-cs-560n1516?cId=&rbl=)

## Raised, flattened and oriented sheets

The Expanded Metal Company notes that flattening reduces material thickness and gives different measurement terminology for flattened mesh. Its guide also states that orientation changes mechanical and visual behavior. A 2440 mm LWM × 1220 mm SWM panel is not interchangeable with a 1220 mm LWM × 2440 mm SWM panel merely because their outside rectangles have the same dimensions. [Manufacturer's raised/flattened and orientation guidance](https://www.expandedmetalcompany.com/news/post/how-to-measure-and-specify-expanded-metal.html)

Show the pattern direction on the panel drawing. Identify the visible face when appearance matters, and the required direction across supports when structural behavior matters. Do not rely on a photograph, “length first” assumption or nominal width×length entry to convey all three.

A raised sheet's depth can control fit into a frame even when the starting gauge seems thin. A flattened sheet needs its finished thickness, not just a starting-sheet designation. McNICHOLS also asks purchasers to specify fabrication, edge treatments and nonstandard tolerances; if a frame requires controlled flatness or squareness, make those requirements explicit. [McNICHOLS order requirements](https://assets.mcnichols.com/content/dam/mcnichols/resources/PDF/EM-Specify-Order.pdf)

## Bounded product and mass example

McNICHOLS item **560N151648**, “1-1/2 inch No. 16 Flattened,” is a 48×96 inch cold-rolled carbon-steel sheet with mill finish. Its record lists:

| Property | Published value |
| --- | --- |
| SWD / LWD | 1.330 / 3.150 inches |
| SWO / LWO | 1.092 / 2.750 inches |
| Strand width / thickness | 0.119 / 0.048 inch |
| Overall thickness | 0.048 inch |
| Open area | 82% |
| Weight per area | 0.35 lb/ft² |

The LWO runs parallel to sheet length, and dimensions may vary within mill tolerances. The nominal style “1-1/2” is therefore not a promise of a 1.5-inch clear opening. [Exact McNICHOLS product record](https://www.mcnichols.com/expanded-metal/flattened/carbon-steel-cs-560n1516?cId=&rbl=)

**Original calculation:** gross sheet area is `(48/12) × (96/12) = 32 ft²`; estimated sheet mass is `32 × 0.35 = 11.2 lb`. At the catalogue's 82% open area, the nominal projected open area is `32 × 0.82 = 26.24 ft²`. These are estimates before cutting, edging, coatings or frames; they do not establish airflow, pressure drop or a panel load rating. Geometric open area is only one input to a performance assessment.

## Load tables: identify the quantity and support case

Expanded-metal grating tables should be read as product-specific load/deflection information. Marco defines **clear span** between inside edges of supports. Its uniform load U is in pounds per square foot; concentrated load C is in pounds per foot of grating width perpendicular to the span. The numerical table entries are deflections in inches, not allowable loads to be applied indiscriminately to any panel. [Marco load-table definitions](https://www.marcospecialtysteel.com/content/uploads/2020/12/Expanded-Metal-Grating-Load-Table.pdf)

For its **3.14# carbon-steel grating at 2-foot clear span**, Marco lists 0.115 inch deflection under **100 lb/ft² uniform load**. Under the separate 100 lb/ft-width concentrated-load case, it lists 0.094 inch. The equal-looking “100” column does not mean equal physical loading. [Marco 3.14# table](https://www.marcospecialtysteel.com/content/uploads/2020/12/Expanded-Metal-Grating-Load-Table.pdf)

## Edges, finish and receiving checks

McNICHOLS asks for a shearing preference, such as **bond shear or random shear**, as well as framing/accessory requirements. Put the required edge condition on the fabrication drawing, especially where it affects fit or attachment. [McNICHOLS cut-size and shearing requirements](https://assets.mcnichols.com/content/dam/mcnichols/resources/PDF/EM-Specify-Order.pdf)

The Expanded Metal Company's product sheet warns about cuts or grazes during handling and recommends suitable PPE. It also states that its nominal dimensions do not guarantee squareness or flatness and that surface marks can occur. Those product terms should not be mistaken for acceptance of any damage; agree project-specific limits when appearance, assembly or function requires tighter control. [Manufacturer quality and handling notes](https://www.expandedmetalcompany.com/media/productattach/p/0/P00927_raised_V1.1.pdf)

At receipt, check the ordered material and finish, raised/flattened form, pattern, labeled dimensions, orientation, edge condition and quantity against the agreed drawing. Keep coating and corrosion requirements separate from the mesh geometry. If a coating or subsequent fabrication changes an opening or connection detail, inspect the finished condition relevant to its use.

## Editions and useful order record

The manufacturer's measuring article is dated **March 5, 2024**, with a displayed modification date of July 8, 2024. Its P00927 PDF carries **©2018**, while Marco's load table prints **12.2020**. McNICHOLS's cited product page and order guide display no technical revision date.

ASTM's catalog lists **F1267-26** as active, updated October 30, 2026, and marks **F1267-18(2023)** historical. Do not call the older edition current solely because a supplier catalogue references it; confirm the governing edition and applicable requirements when ordering. This reference does not reproduce the standard's full tables or establish compliance. [Current ASTM edition](https://store.astm.org/f1267-26.html), [historical edition record](https://store.astm.org/f1267-18r23.html)

A useful order combines base material/grade, finish, exact supplier pattern, raised or flattened form, pitch and opening requirements, strand and overall thickness, sheet orientation, cut sizes, edges and agreed tolerances. Add qualified loading or guarding requirements when relevant. See [Stock forms and dimensions](index.md).