Watertight Expansion Joints and Construction Sealants by EMSEAL


Secondary sealant to liquid sealants for joints in walls

A joint sealant for building walls and wall systems, Backerseal is an economical, precompressed, secondary joint sealant to field-applied caulking. Backerseal is a polyurethane foam infused with a hydrophobic-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 very difficult to install to achieve the geometry necessary to function in moving joints. In addition, the same forces (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. Backerseal works in compression providing a practical-to-install, fully functional secondary joint sealant using different performance principles than the primary, liquid sealant.  Additionally Backerseal provides insulation and sound attenuation value as well as the ability to resist the effects of air-pressure differentials.


Secondary sealant to liquid sealants for joints in walls


  • Provides watertight secondary seal
  • Provides R-value at joints
  • Resists air pressure  differentials/ABAA compliant
  • Remains firmly in compression against substrates
  • Contributes to LEED
  • Odorless
  • Sound Attenuating
  • Clean handling
  • Non-staining
  • UV stable
  • Low temperature flexible
  • High-temperature stable


Standard sizes | 1/4″ (6mm) to 1 1/4″ (30mm).
Custom sizes | 1/8″ (3mm) to 6″ (150mm).


+25%, -25% (50% total) of nominal material size.




As a secondary sealant behind:

  • Conventional backer-rod and liquid sealants
  • Behind directly-applied liquid sealant

Ideally suited to:

  • panelized wall systems
  • curtain wall systems
  • window perimeters
  • precast panels
  • concrete
  • brick
  • stone
  • metal panels, etc.

(Note: Backerseal was formerly named GreyflexTM and may still appear in legacy specifications that way.)

Non-Invasive Anchoring—there are no hard metal-to-concrete connections in the system. This includes embedded pins, anchors, screws, bolts or tracks, trays or rails. The system is held in place by the backpressure from the foam.

Aesthetics & Versatility—Standard color is gray, compatible with most sealants, and an enhanced ability to handle variations in joint size are among other system features.

  • Permanently elastic, high-density, open-cell polyurethane foam, impregnated with a hydrophobic-acrylic impregnation technology.
  • The material is precompressed to less than the joint size for easy insertion.
  • The material is supplied in either 13.12 LF (4m) reels or 6.56 LF (2m) sticks in shrink-wrapped packaging. After removal from the shrink-wrap, it expands gradually.
  • Substrates must be clean, parallel, plumb, have sufficient clear depth to receive the material specified, and be capable of resisting approx. 2.5 psi backpressure from the foam.
  • As with any construction product, the useful life of the material can be maximized with routine inspection and repair if required.
  • Clearing of surface debris and inspection will reveal any damage to the product or adjacent substrates that might affect building performance.
  • EMSEAL precompressed sealants are easily repaired–requiring only damaged sections to be removed and reinstalled–not the entire length of the joint as is typical of extruded-seal systems.
  • Available for shipment internationally.
  • Prices are available from local distributors or representatives. For more information, contact EMSEAL.
  • The product range is continually being updated, and accordingly EMSEAL® reserves the right to modify or withdraw any product without prior notice.

Performance Testing:
Water penetration: ASTM E-331
Wind Loading: ASTM E330
Air permeability: ASTM E283-04
STC Rating: ASTM E90-09
OITC Rating: ASTM E90-09
R-Value: ASTM C518-04
Temperature Stability, Bleeding, Staining & Recovery