Bit & GrainBit & Grain

Underlayment Calculator

Calculate the number of underlayment rolls needed for a roof based on area and overlap percentage.

Underlayment Calculator

Calculate rolls of underlayment and feet of drip edge for a roof installation.

Typical: 10% side-lap per NRCA. Steep slopes may require more.

Perimeter length of eaves and rakes receiving drip edge

Rolls of Underlayment23rolls
Drip Edge200linear ft
Roll size assumed: 36-inch wide, 400 sq ft per roll (standard roofing felt). For synthetic underlayment, check manufacturer specs for actual roll coverage.

For reference only. Verify with your local building code and a licensed professional before making decisions.

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