Roofing Sheet Screw Calculator
Estimate roofing screw quantities from the number of sheets, support lines, fasteners per support, side-lap fixings and procurement allowance.
Fixing assumptions
Roofing screw requirement
How roofing screw quantity is estimated
Every support crossing can create several fixing points along a sheet. Side-lap stitching adds another group of fasteners, particularly where adjacent sheet edges must be secured.
Lap screws = sheets × lap screws per sheet
Base screws = support screws + lap screws
Planning quantity = ceiling(base × (1 + allowance))
Worked example
For 80 sheets, 5 support lines and 4 screws per support, support fixing demand is 1,600 screws before side-lap and allowance components.
Why screw count is not purely geometric
Wind loading, sheet profile, support material, edge zones and manufacturer's fixing patterns can change the required number and type of fasteners. This tool therefore keeps the fixing assumptions visible instead of pretending there is one universal spacing rule.
Procurement boxes
Because screws are commonly purchased in packs, the tool rounds the planning quantity upward to full boxes.
Limitations
This is a quantity estimator, not a structural fixing design. Use project-specific design requirements for safety-critical or regulated installations.
Frequently Asked Questions
Does support spacing affect screw count?
Yes.
Are side-lap screws always required?
That depends on the roofing system.
Can I calculate boxes?
Yes.
Does this choose screw type?
No.