Flexible Copolymer Water Resistive (WRB) / Air Barrier

320/ft² (29.73/m²) per Pail @ 0.75 mm (29.53 mils)


AirStop Water Resistive Barrier Barrier/Air Barrier is a waterborne coating with multi-function features that can be spray or trowel-applied

  • Highly flexible, bridges crack which may form in the substrate
  • Vapour permeable, minimizes risk of condensation in the wall from water vapour diffusion
  • Liquid application assures a monolithic, seamless membrane
  • Water resistive (WRB) air barrier membrane & tie-In membrane
  • Exceptional adhesion to Oriented Strand Board sheathing (OSB), Plywood, expanded and extruded polystyrene
  • Self-seals around nails, forming a tight, seamless barrier against water and air leakage

AirStop is intended to be used as a Water Resistive Barrier/Air Barrier within the building envelope. When used in combination with Barrier Seam Tape, AirStop  provides the continuity of the WRB/Air barrier around window and door rough openings and functions as well as a tie-in membrane over window flanges and door jambs, providing  easier application and lowering installation costs than other conventional products (i.e. butyl flashing tapes or plastic sill pans). 

AirStop can be applied to most common surfaces such as concrete, brick, concrete block, glass-mat coated gypsum, cement board, Plywood and Oriented Strand Board (OSB) and integrated into various Durex® EIF Systems for both new and retrofit construction.

Physical Properties
Product Type

Water-based copolymer


Red viscous material in its liquid state

Specific Gravity


ph Level


Application Temperature

Above 2°C (35°C)


30-35m² (320-370ft²)/pail @ 0.75 mm (0.030") WFT

Performance Properties
Method Results
Bond Strength


  • 0.44 MPa (64 psi) glass matt gypsum
  • 1.85 MPa (268 psi) on concrete
Tensile Strength


1.10 MPa (160 psi)



450% elongation at break

Joint Disruption Resistance

CCMC E.1-16

PASS 2mm & 4mm Joints (deflection up to L/180)

Nail Sealability

ASTM D1970

PASS @ 1.4mm(0.055”) & 1.0mm(0.040”) & 0.75mm(0.030”) WFT

Air Leakage

- CAN/ULC S741-08 (Standard for Air Barrier Materials)


-ASTM E-2178-13 (Standard Test Method for Air Permeance of Building Materials)

PASS   requirement <0.002 L/(s.m2)  @ 75 Pa 

Actual 0.0015L/(s.m2)  @ 75 Pa @ 0.57mm (0.023”) DFT

PASS   requirement <0.002 L/(s.m2)  @ 75 Pa 

Actual 0.0015L/(s.m2)  @ 75 Pa @ 0.57mm (0.023”) DFT

Water Vapour Permeance


Thickness               Method A             Method B

@ 1.4mm             115 ng/Pa.s.m2     331 ng/Pa.s.m2

(0.055”) WFT            (2 perms)              (5.8 perms)

@ 1.0 mm            136 ng/Pa.s.m2    344 ng/Pa.s.m2

(0.040”) WFT       (2.4 perms)              (6 perms)

@0.75 mm         185 ng/Pa.s.m2      505 ng/Pa.s.m2

(0.030”) WFT       (3.2 perms)             (8.8 perms)

Coefficient of Water Absorption

CCMC 5.5.1

0.0001 kg/m2.s1/2 @ 0.75mm (0.030”)