Roof materials
Ice and water barrier calculator
Estimate ice-and-water barrier. Eaves, valleys, or vulnerable roof areas.
Try the calculation
Estimate a protected rectangular barrier area.
Adjustable example. Change these illustrative inputs to match your task, then recalculate. Reset restores the example and its result.
Understand the result
How this calculation works
A barrier estimate starts with the rectangular strip that must be protected.
Steps
- Enter protected length and width, then enter the roll coverage.
- Use the width required by the project detail.
The form starts with the worked example below. Change its values and selections to match your task; Reset restores the example.
Formula
protected area = length × width; rolls = ceiling(protected area ÷ roll coverage).
Variables and units
- Protected length (ft)
- Required. Use a positive value. Starting example: 100. Replace it for your task.
- Protected width (ft)
- Required. Use a positive value. Starting example: 2. Replace it for your task.
- Roll coverage (sq ft)
- Required. Use a positive value. Starting example: 200. Replace it for your task.
What the result means
This is a measured strip estimate. It does not decide whether a valley, eave or other location requires the barrier.
Worked example
Inputs: Protected length = 100; Protected width = 2; Roll coverage = 200.
Calculation: 100 ft × 2 ft = 200 sq ft; at 200 sq ft per roll, the result is 1 roll.
Result: 1 rolls.
Frequently asked questions
Can width be the product width?
It should be the installed protected width for your detail.
Does this include side laps?
Use effective roll coverage after the selected product lap.
Is this a code determination?
No. Confirm the application with the applicable instruction or code.