Roof Valley Liner Calculator
Estimate valley liner material from measured valley length, roll length, end-lap requirements and a visible allowance for cutting and detailing.
Valley liner inputs
Valley liner requirement
How valley liner quantity is estimated
Long valleys can require joined pieces when one roll or sheet cannot span the whole run. End laps therefore need to be included in the linear material takeoff.
Pieces per valley is based on effective roll coverage after end laps
Planning quantity = measured material requirement × (1 + waste)
Rolls = ceiling(planning material length ÷ roll length)
Worked example
Three 8 m valleys create 24 m of base valley run. Adding 2 m of detailing length produces 26 m before the cutting allowance.
Why width remains explicit
A 500 mm liner and a 1,000 mm liner can cover the same valley length but represent different products and detailing arrangements. Width is therefore recorded as a product parameter rather than silently assumed.
Valley layout matters
Actual quantities can change around eaves, ridge transitions, overlaps and intersections. A roof drawing remains the best source for detailed quantity takeoff.
Frequently Asked Questions
Does end overlap increase material?
Yes.
Are valleys all the same?
No.
Can I include extra detail length?
Yes.
Does this design the valley?
No.