SBS MultiPurpose Underlayment

SBS MultiPurpose Underlayment

LeakBarrier SBS MultiPurpose Underlayment is a unique and highly versatile glass fiber reinforced sheet sandwiched between two layers of superior quality polymer modified bitumen. Due to its remarkable characteristics, SBS MultiPurpose Underlayment meets the requirements of the ASTM D1970 Moisture Vapor Permeability and ASTM D4869 liquid water transmission tests.


LeakBarrier SBS MultiPurpose Underlayment is designed for use under composition shingles, shake applications, all types of tile, and metal roofing. 

Features and Benefits

  • Use as an alternate for 15, 30 & 40# saturated felt
  • Greater exposure time than ASTM D226 felts as inorganic glass fiber mat resists the long term effects of moisture
  • Excellent as a valley liner
  • Cost-effective
  • Versatile sheet; can be installed in a variety of applications.
  • Easy to handle
  • Good durability
  • Excellent deadfold characteristics
  • Self-sealing around nails
  • Superior pliability of specially formulated SBS asphalt facilitates a wrinkle free flat laying sheet
  • Fiber glass reinforcement eliminates the rot prevalent with saturated felt
  • Manufactured with 8 ply lines
  • Meets ASTM D226 Type I and II; ASTM D4601
  • Surpasses ASTM D6380 Class S Type IV requirements (applicable sections)
  • Passes ASTM D4869 Liquid Water Transmission test
  • Passes ASTM D1970 Moisture Vapor Permeability Test
  • Complies with the requirements of the International Residential Code (IRC) for Valley Lining material.
  • UL Classified (R13228) for use in class A and B roofs.


  • Store rolls in a dry location, protected from the elements
  • Do not store rolls in direct sunlight for prolonged time
  • Store rolls upright
  • When storing two pallents high, position a plywood sheet between pallets

General Precautions

  • Install SBS Multipurpose Underlayment in strict compliance with applicable building code.
  • Keep rolls clean and free from moisture prior to installation.
  • Follow Occupational Safety and Health Administration (OSHA) safety standards; use common sense measures and adequate precautions to prevent accidents.
  • Ensure proper ventilation of the attic

Surface Preparation

  • The substrate shall be clean, dry, and free of voids prior to installing SBS Multipurpose Underlayment.


  • For ease of application, cut the roll into management lengths prior to use.
  • Follow standard roofing practive when installing SBS Multipurpose Underlayment.
  • Slopes 2/12 to 3/12

For composition roofs install two plies lapping a minimum of 2 inches on side laps and a minimum of 6 inches on end laps. Mechanically fasten to hold in place. For tile roofs see UBC 15 or Tile Manufacturer specifications.

  • Slopes 3/12 and greater

Install one ply lapping a minumum of 2 inches on side laps and a minimum of 6 inches on end laps. Mechanically fasten to hold in place. Install two plies over valleys, hips and ridges.

Property Typical Value Reference Test
High/Low Temperature Unrolling >2% ASTM D6163
Breaking Strength >44 lbf/in ASTM D146
Elongation >2% ASTM D6163
Tear Strength 35 lbf ASTM D6163
Moisture Content 0 ASTM D146
Pliability Pass ASTM D6163
Compound Stability Pass ASTM D6163
Dimensional Stability <0.5% ASTM D6163
Liquid Water Transmission Pass ASTM D4869
Moisture Vapor Permeability 0.1 U.S. Perms ASTM D1970

Product Data

Width 36 in.
Length 66 ft. 8 in.
Thickness 40 mil (nominal)
Gross Coverage 2 Squares
Weight 64 lbs. (nominal)


See our Frequently Asked Questions about this product.

LeakBarrier SBS Multipurpose Underlayment is warranted to be free from manufacturer's defects.

Note: All statements information and data given herein are believed to be accurate and reliable, but are presented without guaranty, warranty or responsibility of any kind, expressed or implied, except as may be indicated otherwise in this literature.

Documents - SBS MultiPurpose

Quick Reference Product Guide

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