Synthetic Roof Underlayment

The economical underlayment choice with a 25-year warranty.

  • 2.5 times lighter per square than #15 felt
  • 25 times stronger than #15 felt
  • 180-day UV resistance
  • High-strength woven fabric, polypropylene-coated on both sides
  • Specially formulated anti-slip walking surface
  • Printed nail locations and 3” overlap line
  • 100% asphalt-free
  • Made in the USA
  • 100% post-consumer recycled materials
  • Miami-Dade County Code approved
  • ICC-ES ESR-3361

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HydraShell™25 is the most slip-resistant underlayment in the industry, and yet another example of Marco quality and value. Stronger, lighter and safer than conventional felt roofing paper, HydraShell25 is made with high-strength woven fabric that is polypropylene coated on both sides. Its specially formulated anti-slip walking surface is 100% asphalt free, offering a safer alternative to conventional roof underlayments. 2.5 times lighter per square and 25 times stronger than #15 asphalt felt paper, HydraShell25 is also UV-resistant and can be exposed for up to six months.


Weight Per Square: 2.8 lbs
Width/Roll Length: 48”/250’
Fire Rating: UL Class A
Nail Seal Ability: Pass
Water Transmission: Pass
Tear Strength: 36 lbs MD/36 lbs CD
Pliability: Pass
Water Ponding: Pass
Coefficient of Friction
     Static: Printed Side 1.022
     Kinetic: Printed Side 1.006

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Easy, One Person Installation

HyrdraShell25 is lighter than felt so its easier to handle. It comes 10 squares to a roll, offering more coverage per roll, and is pre-printed with a nailing pattern for easier installation.

Step 1:

Lay out horizontally on the eave, printed side up, with 3” horizontal laps and 6” vertical laps.

Step 2:

Fasten with 1” diameter plastic cap roofing nails or staples according to pre-printed nail pattern.