Roll Self-Adhered Roofing Underlayment (225 sq. ft.)
How much roofing underlayment do I need?
Underlayment usually comes in rolls of 4 squares each. So, covering 240 squares would require 60 rolls of underlayment. No underlayment is needed if you are applying shingles directly over an existing asphalt roof. Be sure to add 10% to all of your material totals for trim allowance.