Maintain Your Design Integrity on the Job Site
As an architect, you know that designing modern commercial buildings is a labor of love that takes countless hours to achieve. That’s why in a time when the building envelope is expected to be aesthetically pleasing and energy-efficient, and have a positive impact on the environment, architects are more concerned than ever that their design intent is preserved throughout the construction process.
One component that can have a significant impact on a building envelope’s design intent is the water-resistive and air barrier (WRB-AB). Your design of the continuous plane around the envelope to resist bulk water and prevent uncontrolled air movement in and out of the building has the potential to be degraded during the construction process. This can leave many lingering questions both in the planning phase and once construction begins. What if the water control layer design is altered through substitution? What if the WRB-AB is applied in inclement weather? What if it’s applied inconsistently or incorrectly? What if the finished WRB-AB is too difficult to QC and intrusions are left in-service?
With those issues in mind, let’s look at three common WRB-AB’s – building wraps, fluid-applied, and self-adhered membranes – along with an integrated sheathing solution, DensElement® Barrier System with AquaKor™ Technology, which integrates the WRB-AB into the gypsum core to create a hydrophobic, monolithic surface that blocks bulk water but allows vapor to pass through. Exploring the design degradation risk of each, with respect to the WRB-AB specified, tells an interesting story about maintaining the integrity of your design.
While commercial-grade building wraps work well as WRB-ABs, they are difficult to seal, which can compromise their effectiveness as an air barrier. When installed incorrectly – for example, with staples – their WRB effectiveness is degraded. Even when correct fasteners are used and applied to manufacturer’s specifications, they can cause holes in the membrane that allow water and air to penetrate. Since precise taping is required around penetrations such as windows and doors to prevent leakage, misapplication can cause water intrusion. And wraps are prone to blowing off the envelope during prolonged installations, causing more sizeable holes, rips and tears, or complete disengagement of the wrap from the sheathing.
While fluid-applied membranes can serve as both a WRB and air barrier and can generally be installed faster than building wraps, their performance can vary based on how well they’re applied.
“When an architect specs a fluid-applied WRB-AB, there are concerns about how effective the end result will be,” says Ryan Lutz, architect at Anderson Mason Dale Architects P.C.
If the layer isn’t consistent, it can compromise their effectiveness. This makes quality control tedious, as the sheathing must be inspected with a wet mil gauge to ensure the membrane was applied at the proper thickness. And they have weather limitations – if the substrate on which the barrier is being applied is too humid or wet, it can lead to incomplete bonding between the materials. Also, the preparation of sheathing joints and fasteners prior to spraying or rolling on the membrane introduces the opportunity for application issues.
Self-adhered membranes may also serve as both a WRB and AB. But while they don’t have the strict mil-thickness requirements of fluid-applied membranes, and fasteners and sheathing joints don’t need to be sealed before application, installation is quite labor intensive, typically requiring at least a two-man crew to manage the material with its adhesive pre-applied. Also, they generally require a primer that can cause them to wrinkle or compromise their adhesion to the sheathing. And like fluid-applied WRB-ABs, adhered membranes also have weather constraints. If the substrate on which the barrier is being applied is too damp, it can lead to incomplete bonding between the materials. And self-adhered membranes must be applied in “shingle fashion” with overlapping seams to form a continuous barrier. If these seams aren’t aligned correctly, they can form gaps or “fish mouths” between the sheets that allow water to penetrate.
The issues posed by all these products can compromise a building’s design intent, causing problems ranging from delayed dry-in to bulk air and water penetration both during construction and in-service. On the other hand, DensElement® Barrier System provides a high-performance integrated WRB-AB solution for architects concerned with preserving the integrity of their building designs from inception to completion.
DensElement® Barrier System uses proprietary AquaKor™ Technology to create the WRB-AB within. It integrates the gypsum core and fiberglass mat in the factory under controlled conditions to form a hydrophobic, monolithic surface that blocks bulk water but allows vapor to pass through. When the joints, fasteners, openings, and transitions are properly sealed with PROSOCO R-Guard® FastFlash®, DensElement® Barrier System eliminates the need for a separate WRB-AB. In turn, this eliminates the risk of post-design WRB-AB changes to the envelope design, as well as the risk of inconsistent WRB-AB application in the field.
According to Lutz, whose recent projects include the expansive new Greeley City Center, which houses the city’s municipal court house, TV station, and IT and water departments in Greeley, Colorado, the DensElement® Barrier System offers relief from the quality control challenges posed by building wraps and both self-adhered and fluid-applied membranes.
“Sure, after it’s been applied, we can test a fluid-applied membrane with a wet mil gauge,” he explains, “but we can’t test every square inch of the building to see if it received an even, consistent coat. And with other products such as building wraps and peel-and-stick membranes, you don’t know if they’ll be damaged during installation. With the DensElement® Barrier System, you don’t have to worry about that because the WRB-AB is integrated.”
Lutz also notes the application benefits of DensElement® Barrier System as a means of ensuring the design intent of his projects.
“When a crew comes in to spray the fluid-applied WRB-AB, you have to get your workers off the walls and clear the site,” Lutz says. “They didn’t have to do that with the DensElement® Barrier System, which made it much easier to manipulate the schedule and manage the Greeley Center project. And the PROSOCO R-Guard® FastFlash® is definitely easier to use in cold weather,” Lutz continues. “Even when it was in the 40s here, it was easier to install the PROSOCO R-Guard® FastFlash® than spraying a fluid-applied WRB-AB on a warm, 70-degree day. The product is also easy to get – contractors have tubes of it stashed in their trailers – and you don’t need to hire a specially trained crew to apply it.”
Another benefit for architects is the fact the DensElement® Barrier System will support nearly any cladding type, allowing you to design the façade of your choice with confidence. It works under brick, metal panels, rain screen, inverted walls, EIFS, stone, and fiber cement siding. And since the DensElement® sheathing is non-combustible, it is exempt from NFPA 285 assembly testing per the 2018 International Building Code requirements. This makes it an ideal solution for use in wall assemblies that are already NFPA 285 tested. Simplified installation, optimal protection against bulk water infiltration, and the versatility to work with a wide range of cladding options makes DensElement® Barrier System a clear choice for protecting your design.
“From a design perspective, spec’ing DensElement® Barrier System is an easy way to integrate a WRB-AB into a project,” says Lutz. “It makes it easy to draw up the details because it’s integrated right into the sheathing. It’s an innovative product that provides a stable, consistent control layer that allows us to use a myriad of different cladding types over it.”
Through its integration of two formerly separate trade responsibilities – the application of the sheathing and WRB-AB – DensElement® Barrier System also eliminates the “by others” compatibility issues of multiple trades on the moisture control layer and transitions to other materials. The system meets all applicable ASTM standards, including fastener seal ability. In fact, when RDH Building Sciences in Waterloo, Ontario, was commissioned to conduct water penetration testing using ASTM E331 methodology that stressed the DensElement® Barrier System at the cladding fastener penetrations, its performance is comparable with the performance of thin- and thick-mil fluid-applied membranes over fiberglass-mat gypsum sheathing. And the high vapor permeability of DensElement® Barrier System provides excellent drying capability.
“Many fluid applied WRBs have moderate to low vapor permeance,” explains Georgia-Pacific Gypsum’s Senior Product Manager, John Chamberlin. “When applied over glass-mat gypsum sheathings, many fluid-applied WRB-AB’s effectively trap residual moisture inside the building, which diminishes the drying capability of both the sheathing and the assembly. On the other hand, the high vapor permeability of the DensElement® Barrier System allows moisture to escape, which reduces the potential for damage when water does manage to infiltrate the building envelope.”
Reduce the risk of the degradation of your moisture control layer designs by specifying the sheathing system with the WRB-AB within. DensElement® Barrier System with AquaKor™ Technology provides the performance and versatility you need to preserve your design intent through the entire construction process and help protect the structural integrity of the building for you, owners and occupants throughout the building’s lifespan.