Roof Tarp Calculator

| Added in Construction

What is Roof Tarp Sizing?

A roof tarp provides emergency protection for a damaged roof until permanent repairs can be made. Calculating the correct tarp size ensures full coverage of the affected area with enough extra material to secure the edges and handle irregular shapes. Undersizing a tarp leaves gaps for water intrusion, while oversizing wastes money.

How to Calculate Roof Tarp Size

Here is the formula:

[\text{Tarp Size} = \text{Roof Area} \times 1.5]

Where:

  • Tarp Size is the recommended tarp area.
  • Roof Area is the measured area of the section that needs covering.

Both values use the same area unit (ft² or m²). The 1.5 multiplier accounts for overlap, edge securing, and roof features.

Calculation Example

A damaged section of roof measures 700 ft².

[\text{Tarp Size} = 700 \times 1.5 = 1{,}050]

You need a tarp of at least 1,050 ft² to properly cover and secure the area.

Frequently Asked Questions

The 1.5 multiplier ensures the tarp extends beyond the damaged area on all sides. This extra material is needed to fold over the edges, secure with nails or weights, and account for roof features like ridges and vents that require extra coverage.

Yes. The 1.5 multiplier works as a general guideline for flat, gable, hip, and other roof types. However, roofs with many valleys, dormers, or complex features may need a slightly higher multiplier to ensure full coverage.

Look for a heavy-duty, waterproof tarp with UV resistance. Poly tarps rated at 10 mil or thicker are common for roof applications. Blue tarps are widely available, but silver or white tarps reflect more heat and last longer in direct sunlight.

Spread the tarp over the damaged area with extra material extending beyond the edges. Secure the edges with 2x4 lumber strips nailed into the roof deck, or use sandbags and bungee cords for temporary fixes. Ensure the tarp sheds water away from the damage, not toward it.

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