PANEL DIMENSIONS & COVERAGE REFERENCE
Metal Roof Panel Width: Nominal Width vs. Net Coverage
When calculating metal roof materials, overall panel width is not the same as net coverage width. While a corrugated panel may measure 38 inches wide overall, it provides exactly 36 inches of installed coverage after subtracting panel lap ribs. Standard standing seam panels provide 16 or 12 inches of net coverage.
The Golden Panel Sizing Rule
Always calculate required panels using Net Coverage Width, never nominal overall width.
$$text{Panels Required} = leftlceil frac{text{Roof Ridge Length (in)}}{text{Panel Net Coverage Width (in)}} rightrceil$$
Standard Metal Roof Panel Widths by Profile
| Metal Panel Profile | Nominal Overall Width | Net Coverage Width | Lap / Seam Loss |
|---|---|---|---|
| Standard Standing Seam (Snap-Lock) | ~17 to 18 inches | 16 inches | 1 to 2 inches (Seam locks) |
| Architectural Standing Seam (Narrow) | ~13 to 14 inches | 12 inches | 1 to 2 inches |
| Commercial Standing Seam (Wide) | ~19 to 20 inches | 18 inches | 1 to 2 inches |
| Corrugated Sheet (Standard 36″ Net) | 38 to 38.5 inches | 36 inches | 2 to 2.5 inches (1.5 wave lap) |
| R-Panel / PBR-Panel | 38.5 inches | 36 inches | 2.5 inches (Overlapping rib) |
| 5V-Crimp Agricultural Panel | 26 inches | 24 inches | 2 inches (Double-V lap) |
Worked Panel Calculation Example
Suppose you are installing standing seam metal panels with a 16-inch net coverage width on a gable roof section with a 40-foot (480-inch) ridge length:
$$text{Panels per Side} = frac{480text{ inches}}{16text{ inches}} = mathbf{30text{ Panels}}$$
For both sides of the gable roof, you will order a total of $30 times 2 = mathbf{60text{ Panels}}$.
Calculate Your Project Panels Instantly
Use our dedicated Metal Roofing Calculator to enter your roof length and slope to calculate exact panel counts and linear feet.