Roof Ridge Material Calculator
Estimate ridge-cap quantities from the actual ridge run, effective cap coverage after overlap and a visible cutting allowance.
Ridge inputs
Ridge-cap requirement
How ridge-cap quantities are calculated
Ridge caps overlap each other, so nominal cap length is not the same as effective ridge coverage. This calculator converts the supplied cap length into a net coverage figure before rounding.
Theoretical caps = ceiling(ridge length ÷ effective coverage)
Order quantity = ceiling(theoretical caps × (1 + waste)) + special pieces
Worked example
For 36 m of ridge using 450 mm caps with 100 mm overlap, each repeating cap contributes approximately 350 mm of effective run in this simplified model.
Why special pieces stay separate
End closures and other proprietary pieces are not interchangeable with standard ridge caps. Keeping them separate avoids accidentally treating accessories as straight-run units.
Hip runs are different
Hip caps should normally be measured separately because their geometry and quantity can differ from the main ridge run.
Frequently Asked Questions
Does overlap reduce cap coverage?
Yes.
Should hip tiles be included?
Usually measured separately.
Can I add special pieces?
Yes.
Does this design ridge ventilation?
No.