Emseal Backerseal


For use in walls and wall systems, BACKERSEAL is an economical, high-performance, secondary sealant to field-applied caulking featuring EMSEAL's exclusive, microcell-modified, acrylic impregnation technology.

Unlike 'double caulk and backer rod', BACKERSEAL behind field-applied liquid sealants provides true "belt and suspenders" sealing - two systems working on different principles to perform the same function.

'Double caulk and backer rod' is not only very difficult to install to achieve the geometry necessary to function in moving joints, but the same forces (primarily tensile stresses at the bondline and within the cured sealant) that will cause the outer installation to fail, will also likely cause the inner installation to fail as well.

By contrast, BACKERSEAL, because it works in compression, provides a practical to install, fully functional secondary seal using different performance principles than the primary, liquid sealant. In addition it provides insulation and sound attenuation value as well as the ability to resist the effects of air-pressure differentials.

Ideally suited to panelized wall systems, curtain wall systems, as well as walls constructed of concrete, brick, stone, metal panels, etc.

Product Description

  • Emseal BACKERSEAL (Greyflex) is an economical preformed expanding foam sealant that provides watertight secondary sealing in applications: 1) behind conventionally installed liquid sealant and backer-rod or, 2) behind directly field-applied low-modulus liquid-sealants. When installed with directly-applied liquid sealant, a binary sealant system (combination of two technologies with performance that exceeds that of the individual components) is created.
  • Emseal BACKERSEAL consists of alternate layers of acrylic-impregnated expanding foam sealant and, where sizes permit, closed-cell (EVA) foam.
  • The expanding foam laminations are open-cell polyurethane foam impregnated with a non-drying, water based, stabilized, polymer-modified acrylic adhesive.
  • BACKERSEAL is supplied in precompressed rolls in widths from 3 mm (1/8”) up to 25mm (1") and in shrink-wrapped lengths (sticks) in widths from 30mm (1 1/4") up to 150mm (10").
  • Supplied precompressed to less than the joint size with a mounting adhesive on one side. It is inserted into the joint and adhered to one joint-face. It then expands to seal the joint.
  • Sealing against the substrate is achieved through a combination of the pressure-sensitive adhesive impregnation, and backpressure from the expanding foam.


  • Facades 
  • Brick and Block 
  • Precast, Stone, Metal and Other Panelized Systems 
  • Acoustic and Anti-Vibration

Elimination of Stack (Chimney) Effect in Curtainwall Systems – As a baffle in vertical mullions of curtainwall systems, BACKERSEAL can mitigate moisture intrusion and the noisy movement of air within vertical mullions known as the “stack effect”.

  • Provides R-value at joints
  • Provides watertight secondary seal
  • Resists air pressure differentials
  • Remains firmly in compression against substrates
  • Provides acoustic dampening
  • Contributes to LEED accreditation's 

Standard sizes: 3mm to 150mm. Custom sizes are available (call Allco to discuss).
Movement capability: +/-25% (50% total) of nominal material size.
Sound Attenuation: with a 63.5mm (2 1/2") standard depth product installed in one side of a STC 68 wall, BACKERSEAL had a STC 53 rating and in an OITC 52 wall it had a 49 OITC rating. When installed from both sides of a STC 68 wall it received the maximum of STC 68 equaling the sound suppression of the wall and in an OITC 52 wall it received a OITC 51 rating.


  • BACKERSEAL will not adhere to joints that are dirty or dustcovered or to surfaces coated with oils or release agents.
  • BACKERSEAL is not resistant to sustained contact with petroleum solvents, oils, selected waxes, active chlorine, heavy oxidized acids or strong lyes.
  • BACKERSEAL is designed for use in vertical surfaces such as walls and facades. It is not intended for use in the horizontal plane such as floors or decks.
  • Substrate faces must be parallel and have sufficient clear depth to fully support BACKERSEAL as well as the liquid sealant to be applied.
  • Substrates must be capable of resisting, without deflection, approximately 2.5 lb/in2 (17 kPa) backpressure from the BACKERSEAL.

Backerseal - Tech Data


Backerseal - Install Data


Backerseal - Safety Data Sheet


The Emseal Checklist