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Corrugated Metal Panel Side Lap Overlap Calculator

Calculate how many corrugated metal panels are needed to cover a roof width, accounting for side lap overlap.

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
65.62 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Panels needed

20 panels

High confidence
Net coverage width per panel
3.28 ft

For the dimensions entered, expect a panels needed of 20. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

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

  • Net coverage width per panel = panel width − side lap width; panels needed = ceil(total roof width ÷ net coverage width per panel)

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Frequently asked questions

Why subtract the side lap width from the panel's full width?
Each panel overlaps the next one along its side lap, so only the net (non-overlapped) width actually adds new coverage across the roof — using the full out-to-out panel width would undercount how many panels are needed.
Does this calculation also cover end lap overlap?
No — this calculator only accounts for side lap overlap across the roof width. If a panel run is longer than one available sheet length, the end lap needed to join sheets end-to-end is a separate calculation not included here.
What happens if I enter a side lap width of 0?
The net coverage width becomes equal to the full panel width, which is the same as assuming no overlap between adjacent panels — this will understate the number of panels an overlapped installation actually needs.