Ice & Water Shield Calculator
Use this ice and water shield calculator to estimate how many rolls you need for roof eaves, valleys, and vulnerable areas. Most rolls cover approximately 200 square feet. For example, covering 400 linear feet of eaves at 3 feet wide requires about 6 rolls before waste.
Enter roof dimensions below to calculate required rolls automatically. For total roof area checks, use the roof squares calculator.
Inputs
Results
Assumptions
- This estimates coverage area, not exact layout.
- Valleys are modeled as a centered membrane run.
- Always follow local code and manufacturer requirements for where membrane is required.
Ice & Water Shield Coverage Reference
| Coverage Area | Rolls Needed (200 sq ft per roll) |
|---|---|
| 400 sq ft | 2 rolls |
| 800 sq ft | 4 rolls |
| 1,200 sq ft | 6 rolls |
| 1,600 sq ft | 8 rolls |
| 2,000 sq ft | 10 rolls |
Most manufacturers recommend full coverage along eaves and valleys in cold climates.
Example
120 ft of eaves with 36-in width, 2 courses, 30 ft of valleys, 200 sq ft rolls, and 10% waste equals about 990 sq ft of membrane, or 5 rolls.
Ice & Water Shield FAQs
Where should ice and water shield be installed?
Typically along roof eaves, valleys, around chimneys, and in areas prone to ice dams.
Is ice and water shield required by code?
Many cold-climate regions require it at eaves. Check local building codes.
How many rolls do I need per square?
One roll usually covers about two roofing squares (200 sq ft), depending on overlap.