Roof Sheathing Calculator

Calculate the number of 4×8 plywood sheets needed to sheath your roof. Account for roof pitch and get accurate material estimates for your roofing project.

Calculate Roof Sheathing Materials

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How to Calculate Roof Sheathing Requirements

Roof sheathing, typically made of plywood or oriented strand board (OSB), forms the foundation for your roofing materials. This comprehensive guide explains how to accurately calculate the number of sheathing panels needed for your roof project.

Roof Sheathing Calculation Formulas

The total number of sheathing panels needed is calculated using these key formulas:

\[ \text{Pitch Factor} = \frac{\sqrt{\text{rise}^2 + \text{run}^2}}{\text{run}} \]

\[ \text{Actual Roof Area} = \text{Length} \times \text{Width} \times \text{Pitch Factor} \]

\[ \text{Panels Needed} = \text{Ceiling}(\frac{\text{Actual Roof Area}}{\text{Panel Area}}) \]

\[ \text{Total Cost} = \text{Panels Needed} \times \text{Cost per Panel} \]

Where:

  • Rise = Vertical rise of roof pitch (feet)
  • Run = Horizontal run of roof pitch (feet)
  • Length = Horizontal length of roof surface (feet)
  • Width = Horizontal width of roof surface (feet)
  • Panel Area = Area of one sheathing panel (typically 32 sq ft for 4'×8' panel)

Calculation Steps

  1. Determine the roof pitch (rise and run)
  2. Calculate the pitch factor
  3. Measure roof length and width
  4. Calculate actual roof area using pitch factor
  5. Determine number of panels needed
  6. Calculate total cost if panel price is known

Example Calculation

Problem:

Calculate sheathing panels needed for a roof with:

  • Roof pitch: 6:12 (rise:run)
  • Roof length: 40 feet
  • Roof width: 30 feet
  • Panel size: 4' × 8' (32 sq ft)
  • Panel cost: $45 each

Solution:

  1. Calculate pitch factor:
    \[ \text{Pitch Factor} = \frac{\sqrt{6^2 + 12^2}}{12} = 1.118 \]
  2. Calculate actual roof area:
    \[ \text{Actual Area} = 40 \text{ ft} \times 30 \text{ ft} \times 1.118 = 1,341.6 \text{ sq ft} \]
  3. Calculate panels needed:
    \[ \text{Panels} = \text{Ceiling}(\frac{1,341.6}{32}) = 42 \text{ panels} \]
  4. Calculate total cost:
    \[ \text{Total Cost} = 42 \text{ panels} \times \$45 = \$1,890 \]

Sheathing Layout Diagram

4' × 8' Sheathing Panel Layout

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