Underseal® Blindside™ Membrane

Underseal® Blindside™ Membrane is a 73-mil, pre-concrete pour, strong sheet membrane waterproofing with a thick, cross-laminated, high-density polyethylene (HDPE) backing, laminated to a thick layer of proprietary waterproofing adhesive compound integrated into a nonwoven geotextile fabric.

Underseal® Blindside™ Membrane is used as a waterproofing membrane where vertical, positive-side waterproofing is required, but access to the positive side is impossible due to the soil retention system.  Once the concrete is poured against the Blindside™ Membrane, the concrete cures and a mechanical bond forms to secure the concrete to the membrane.  Also, subsequent to concrete placement, cold flow of the waterproofing compound will take place and an adhesive bond will be added to the mechanical bond given by the fibers.  With both a mechanical and adhesive bond, the concrete will be tightly sealed and bonded to the membrane, creating superior protection against moisture intrusion. 73-mil Underseal® Blindside™ can also be used in certain horizontal applications. Contact Polyguard for more information.


  • Superior puncture resistance of greater than 217 lbs, which provides strong resistance to concrete construction abuse
  • Rainfall, freeze/thaw and wet/dry cycling do not affect the installed system
  • Flexible material that adapts to jobsite irregularities
  • Fully adhering watertight laps for ease of installation

Photo Gallery

Product Resources

Data Sheet (PDF)Download 
Guide Spec (PDF)Download 
Guide Spec (WORD)Download 
HPD (PDF)Download 
Materials List (PDF)Download 
Features & Benefits (PDF)Download 
SDS (PDF)Download 


PGArch-Detail-BS4-Blindside Penetration Rough Fit Around Penetration Sidewall 03052021Download 
PGArch-Detail-BS5-Blindside Soil Nail Stud Plate Condition 03052021Download 
PGArch-Detail-BS11-Blindside Soil Nail Stud Plate Condition 03052021Download 
PGArch-Detail-BS15-Blindside Polycover Over the Tie Back Soil Nail Assembly 03052021Download 

Repairs / Patches

PGArch-Detail-BS8-Blindside Front View Repair Patch Over Damage Less Than 2 inches 03052021Download 
PGArch-Detail-BS9-Blindside Front View Repair Patch Over Damage Greater Than 2 inches 03052021Download 

Retention System

PGArch-Detail-BS1-Blindside Over Earth Retention System Soldier Pile And Lagging Shown 03052021Download 

Seams / Laps

PGArch-Detail-BS2-Blindside Front View 4 inch Selvage Lap Seam & Fasteners 03052021Download 
PGArch-Detail-BS6-Blindside Front View Side Reinforced Seam 03052021Download 
PGArch-Detail-BS7-Blindside End Lap 03052021Download 


PGArch-Detail-BS16-Blindside Top of Wall Termination Mechanically Fastened 03052021Download 
PGArch-Detail-BS17-Blindside Top Of Wall Embedded Termination 03052021Download 


PGArch-Detail-BS3-Blindside Embedded Tie In To 650 or PRM 03052021Download 
PGArch-Detail-BS10-Blindside With Totalflow Tie In To Underslab 03052021Download 
PGArch-Detail-BS12-Blindside Tie In To 650 or PRM 03052021Download 
PGArch-Detail-BS13-Blindside Vertical Termination of 650 or PRM To Blindside 03052021Download 
PGArch-Detail-BS14-Blindside Tie In With 650 or PRM At Outside Corner 03052021Download 

Product Submittals

For a job-specific submittal package, please contact Polyguard for Product Submittal Requests. Click here to find your area’s field representative.

Companion Products

(where applicable)
606 Tape High strength double-sided tape comprised of rubberized asphalt.
650 LT Liquid Adhesive Used to prime all structural concrete, masonry, or wood surfaces prior to membrane installation.
California Sealant Used to seal all porous portions of Underseal® geotextile surface and promote adhesion of Polyguard sealants.
Detail Sealant PW™ VOC/HAPS-free high performance solvent-free sealant.
Detail Tape Use as detail strips on corners, penetrations, joints, and for patching damaged areas of the membrane.
LM-95 Two-component fast cure urethane waterproofing membrane.
Poly Cover Preformed dome shaped tie back cover made with heavy duty, high impact ABS plastic.
Polyflow® 15 / 15P Sheet molded drain for vertical application with a compressive strength of 15,000 psf.
Totalflow™ A sheet molded high-capacity perimeter drain.
Underseal® Fabric Tape Use around pipe penetrations and at end laps for patching damaged areas of the membrane.
Underseal® Pit Top Corner Boot Preformed corner boot used to reinforce and seal the Underseal® Underslab Membrane and Underseal® Blindside™ Membrane.