Ice and Water Shield Calculator

Calculate the amount of ice and water shield needed for your roof. Essential for protecting against ice dams and water infiltration in eaves, valleys, and other vulnerable areas.

Calculate Ice & Water Shield Coverage

How to Calculate Ice & Water Shield Requirements

Ice and water shield is a critical roofing underlayment that protects against water damage from ice dams and wind-driven rain. This guide explains how to calculate the amount of ice and water shield needed for your roof project.

Ice & Water Shield Calculation Formulas

The total amount of ice and water shield needed is calculated using these formulas:

\[ \text{Eave Area} = \text{Eave Length} \times \text{Coverage Width} \]

\[ \text{Valley Area} = \text{Valley Length} \times (2 \times \text{Coverage Width}) \]

\[ \text{Total Area} = \text{Eave Area} + \text{Valley Area} \]

\[ \text{Rolls Needed} = \text{Ceiling}(\frac{\text{Total Area}}{\text{Roll Coverage}}) \]

Where:

  • Eave Length = Length of roof edge (feet)
  • Valley Length = Length of roof valleys (feet)
  • Coverage Width = Standard coverage width (typically 3 feet)
  • Roll Coverage = Area covered by one roll (typically 198 sq ft)

Calculation Steps

  1. Measure the total length of all eaves requiring protection
  2. Measure the length of any valleys requiring protection
  3. Calculate eave coverage area using standard width
  4. Calculate valley coverage area (if applicable)
  5. Sum the total area needed
  6. Divide by roll coverage and round up to determine rolls needed

Example Calculation

Problem:

Calculate ice & water shield requirements for:

  • Eave length = 40 feet
  • Valley length = 16 feet
  • Coverage width = 3 feet

Solution:

  1. Calculate eave area:
    \[ \text{Eave Area} = 40 \text{ ft} \times 3 \text{ ft} = 120 \text{ sq ft} \]
  2. Calculate valley area:
    \[ \text{Valley Area} = 16 \text{ ft} \times (2 \times 3 \text{ ft}) = 96 \text{ sq ft} \]
  3. Calculate total area:
    \[ \text{Total Area} = 120 \text{ sq ft} + 96 \text{ sq ft} = 216 \text{ sq ft} \]
  4. Calculate rolls needed:
    \[ \text{Rolls} = \text{Ceiling}(\frac{216}{198}) = 2 \text{ rolls} \]

Installation Diagram

Eave Protection Valley Protection

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