Roof Tarp Calculator

Last updated: 22 Sep 2026 | Author: Brij | Review By: Irshad

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Estimate the tarp area needed to temporarily cover your roof, including extra material for overlap and secure anchoring.

Roof Length:

Roof width:

Overlap Length:

Result

Roof Area:

Roof trap:

To estimate the tarp size for your roof. Simply enter the roof's base length, width, and desired overlap, and the calculator will provide the total tarp area required to ensure complete and secure coverage.

What is roof trap?

A Roof Tarp is a protective covering, usually made from waterproof material, used to temporarily shield a roof from weather damage, leaks, or debris. It is often used after storms, during roof repairs, or to prevent water infiltration until permanent fixes are made.

Step-by-Step Process to Find Tarp Area:

Step 1: Calculate Roof Area (A)

The roof area is typically calculated by multiplying the length by the width of the roof base. For a simple rectangular or square roof:

$\text{Roof Area (A)} = \text{Length (L)} \times \text{Width (W)}$

Step 2: Calculate Roof Perimeter (P)

The perimeter of the roof is the total length around the base of the roof, calculated as:

$\text{Perimeter} = 2 \times (\text{Length} + \text{Width})$

Step 3: Calculate Tarp Area

Now, to account for the extra overhang (to secure the tarp around the edges of the roof), we use the formula:

$\text{Tarp Area} = \text{Roof Area} + (\text{Overlap Length} \times \text{Perimeter})$

Example Calculation:

Let’s assume:

Roof Base Length (L) = 40 feet.
Roof Base Width (W) = 30 feet.
Overlap Length = 2 feet (for securing the tarp).

Step 1: Calculate Roof Area (A)

$\text{Roof Area (A)} = \text{40} \times \text{30}$

$\text{Roof Area (A)} = 1200 \text{ square feet}$

Step 2: Calculate Roof Perimeter (P)

$\text{Perimeter (P)} = 2 \times (\text{40} + \text{30})$

$\text{Perimeter (P) } = \text{ 140 feet}$

Step 3: Calculate Tarp Area

Now, using the formula for Tarp Area:

$\text{Tarp Area} = \text{1200} + (\text{2} \times \text{140})$

$\text{Tarp Area} = 1,480 \text{ square feet}$

So, the total tarp area required to cover the roof, including a 2-foot overhang, is 1,480 square feet.

FAQs

1. How long can a roof tarp stay on?

A roof tarp is a temporary solution until permanent repairs are completed. Its lifespan depends on the tarp quality, installation, weather, wind exposure, and roof condition. Inspect it regularly and arrange professional repairs as soon as possible. FEMA also treats tarping as short-term protection rather than a permanent repair. FEMA guidance

2. What size tarp do I need to cover my roof?

Choose a tarp that fully covers the damaged section and extends beyond it so it can overlap the surrounding roof and be securely fastened. Add extra material for the roof slope, overlap, and anchoring.

3. Does the Roof Tarp Calculator include overlap?

The calculator estimates the base tarp area from your roof measurements. Add an allowance for overlap and secure fastening before buying a tarp.

4. Can I install a roof tarp myself?

Only attempt it when the roof is dry, stable, and safe to access. For steep, damaged, wet, or high roofs, contact a qualified roofing professional.

5. Is a roof tarp a permanent repair?

No. A tarp helps limit further water damage while you arrange a permanent roof repair.

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