About

Ordering metal roofing requires precise calculation of effective coverage rather than total sheet width. Manufacturers specify an "Effective Width" for each profile (e.g., Corrugated, R-Panel), which accounts for the necessary side-lap overlap to ensure weatherproofing. Ignoring this difference often results in material shortages.

This tool computes the precise number of sheets required by analyzing the roof's ridge length against the specific profile data of standard international metal sheets. It also estimates the necessary fasteners (screws) based on structural density requirements, providing a complete bill of materials for DIYers and professional roofers.

Formulas

The calculation derives the sheet count from the effective width, not the gross width.

Sheets = ceilRidgeLengthEffWidth

Fastener estimation uses a density constant (ρ) based on the profile type (usually 80-100 screws per square, or roughly 3-4 per linear foot of panel).

Screws = Area × ρ

Reference Data

Profile Type	Total Width	Effective Width	Min Overlap
Corrugated 7/8"	26"	24"	2"
R-Panel / PBR	38"	36"	2"
U-Panel	38"	36"	2"
Standing Seam 16"	18"	16"	Seam
5V Crimp	26"	24"	2"
Trapezoidal (Metric)	1050mm	1000mm	50mm
Metric Corrugated	860mm	762mm	98mm

Frequently Asked Questions

Total Width is the physical width of the metal sheet. Effective Width is the area the sheet actually covers after overlapping with the adjacent sheet. You must always calculate using Effective Width.

Yes, the tool sums the total length of ridges (Ridge Length) to help you order the correct linear footage of ridge cap trim.

A standard rule of thumb for exposed fastener systems (like R-Panel) is approximately 80 screws per 100 sq. ft. (1 square), or roughly 1 screw every 1-2 square feet depending on wind load requirements.