ADHERO and VISCONN Flex Their Airtight & Waterproof Might

ADHERO and VISCONN Flex Their Airtight & Waterproof Might

Although other WRBs may have entered the arena for the ASTM E331 (water infiltration testing) challenge, Pro Clima's ADHERO self-adhered membrane and VISCONN liquid-applied membrane emerge the champions. In independent, third-party tests both succeeded in passing for full 2 hours at 300 pascals of pressure, simulating the most extreme driven rain. For scale, other systems have only attempted up to 15 minutes - at 8 times that amount, 2 hours is a marathon by comparison.

Making ADHERO An IBC/IRC Compliant WRB

The Pro Clima self-adhered membrane ADHERO is known for its great versatility: applicable as a commercial WRB, pitched roof underlayment, and as CLT waterproofing. Even though it is an excellent WRB, with a monolithic TEEE layer that makes it very waterproof and actively vapour-open, the IBC and IRC solely refer to No.15 asphalt felt as an acknowledged weather resistive barrier. There is, however, an exemption for materials that pass the stringent ASTM E331 test, but not at the standard 75 Pa pressure. Per IBC Chapter 14 Exterior wall – in section 1403.2 Weather protection and IRC Chapter 7 – R703 Exterior covering, materials are exempted from other requirements if you can pass the following:

"Exterior wall envelope that has been demonstrated through testing to resist wind-driven rain, including joints, penetrations and intersections with dissimilar materials, in accordance with ASTM E331 under the following conditions:

  • Test one opening, control joint, wall / eave interface and sill
  • Test 4'x8' in size minimum
  • 6.24 pounds per square foot (psf) (0.297kN/m2).
  • Test to last at least 2 hours”

Pro Clima's ADHERO system was installed and tested at INTERTEK in York, PA in accordance with the conditions listed above, on a 2x6 wall sheathed in exterior gypsum. The bottom sill connection was made with EXTOSEAL ENCORS, the ADHERO was then applied to the substrate, after which the connection to the window blank was made with CONTEGA SOLIDO EXO*. The assembly then rested for 24 hours, an important step, as Pro Clima adhesives are pressure activated and achieve full strength one day after pressurization. The wall then successfully withstood the 300 pa (6.24 psf) pressure and water penetration test for 2 hours.

*CONTEGA SOLIDO EXO has since been replaced in our product offerings by CONTEGA SOLIDO IQ

Making VISCONN An IBC/IRC Compliant WRB

VISCONN is Pro Clima's liquid-applied air barrier is known for its great airtightness (ASTM E2178 at 0.000000 L/Pa·m2·s) as well as it watertightness (per EN 1928 as best-in-class W1 rating). However, these European Norms are not widely recognized by the North American building codes. So 475 took the step to prove code compliance. We'd rather not rely on ICC-ES, which would only show equivalence to the code requirement of No.15 asphalt felt. Instead we opted for the stringent ASTM E331. So, VISCONN joined ADHERO on its trip to INTERTEK to be tested with identical E331 conditions, applied on a 4'x8' wall, sheathed in exterior gypsum.

The 6.24 psf (300 pa) pressure is equivalent to a 50 mph wind speed. The connection to the window blank was made with CONTEGA SOLIDO EXO, and the entire assembly was coated with multiple layers of VISCONN to reach 11 mills. The assembly then was cured for a 24 hours, manufacturer recommended drying time is between 12 to 48 hours depending on thickness and substrate. After 2 hours of testing VISCONN passed the water penetration test, making IBC/IRC code validated as a WRB and an absolutely airtight material.

You can now rely on VISCONN for your North American projects as your WRB if installed as per the manufacturer's recommendations and thicknesses.

Behind the Scenes - 475 Product Testing

Sizing Up The Competition

We searched extensively, but could not find another WRB that was able to meet the 2 hour code requirements at 300 pa. Zip System is listed at E331 – 75 pa for 30 minutes. Tyvek lists its commercial wrap for D E331 at 15 psf, but doesn't indicate time and/or if there was a window / eave / sill included. Get in touch with us if you have information we were not able to find publicly online, but for the time being, ADHERO and VISCONN are the only WRBs able to report a successful outcome for E331 at 6.24 psf (300 pa) for 2 hours.


Commercial grade, self-adhered, monolithic, vapour permeable membrane and durable WRB / roof underlayment. Liquid-applied air barrier for robust connections. For use as WRB, flashing for pitched window sills, and other detailing. Use both interior and exterior on CMU / masonry and difficult to seal junctions in any project.