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Metal Roofing Calculator

Panels, screws and trim for a metal roof.

Metal Roofing Calculator
rise 12 span
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ft
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Metal panels are ordered cut to length, so the number that matters is the rafter run from eave to ridge, not the building footprint. Panel coverage width is always less than the sheet width, because the ribs overlap.

How this is calculated

  1. Panels per plane = eave length ÷ the panel's coverage width, which excludes the overlapping rib.
  2. Panel length is the rafter run plus the eave overhang. Order panels cut to that exact length to avoid an end lap.
  3. Exposed-fastener roofs use roughly 80 screws per roofing square.

Frequently asked questions

What is coverage width?

The width a panel actually covers once installed, after the rib overlaps its neighbour. A 38 inch sheet typically covers 36 inches.

Can metal go over shingles?

Often yes, over one layer, with furring strips or a slip sheet. Check local code and the manufacturer's warranty terms first.

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