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Corrugated Metal Decking Span Deflection Checker

Check corrugated steel deck deflection against a code limit, using your deck's own effective moment of inertia.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
9.84 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Calculated deflection

0.03 in

High confidence

PASSES — calculated deflection (0.791 mm) is within the 12.50 mm allowable limit. Remember: the effective moment of inertia must come from your deck manufacturer's or the SDI's own span table for your exact profile and gauge, not a computed section property.

Allowable limit
0.49 in

Running these inputs gives 0.79 mm as the calculated deflection. Allowable limit carries the most weight in this calculation, at 12.5 mm. Note that effective moment of inertia i (×10⁶ mm⁴ per m width) sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Add the equipment this sizes

This result is a specification — 0.031 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Steel Deck Institute Floor/Roof Deck Design Manuals: Δ = 5wL⁴/(384EI) applied per unit width, with E = 200,000 MPa; effective moment of inertia (I) is profile- and gauge-specific and must come from the deck manufacturer's or SDI's own span table — it cannot be derived from a general formula

Your workspace

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Frequently asked questions

Where do I get the effective moment of inertia for my deck?
From the manufacturer's or the Steel Deck Institute's (SDI) span table for your exact deck profile and gauge — effective moment of inertia for corrugated decking depends on the specific corrugation geometry and cannot be derived from a general formula.
Why is the modulus of elasticity fixed at 200,000 MPa?
200,000 MPa (200 GPa) is the standard modulus of elasticity for structural steel, so it is fixed rather than entered by the user for this calculator.
What's the difference between the L/180 and L/360 limits?
L/360 is a tighter limit typically applied where finishes or ceilings below are sensitive to movement, while L/180 is a looser limit sometimes permitted for roof decks without such finishes — confirm which limit applies under your project's governing code.