Problems with Air Barrier Sheathings Like ZIP System®
On the surface, air barrier sheathing products like the ZIP System® and others, seem like a great product. One product that takes the place of two. The sheathing and taping purportedly eliminates the need for an air/moisture wrap or barrier because it is built-in to the sheathing.
However, especially in today’s green building environment, it is imperative that air tight, moisture-resistant barriers perform well. Correct installation is always a key component.
Installation Challenges with Air Barrier Sheathings
Proper installation is imperative with with all types of wraps and barriers. With air barrier sheathings the potential for installation problems is very real. In some situations, the potential for installation mistakes is greater because of a general lack of familiarity with a relatively new concept.
One of the problems with air barrier sheathings such as the ZIP System® is the need to keep seams absolutely smooth, because wrinkles in the tape may compromise the system’s integrity. Because the air barrier sheathings are new, there are questions about long-term tape adhesion.
Some builders have also voiced concerns about the potential movement of the sheathing. Shifting sheathing may have an impact seams, reducing air tightness and potentially leading to condensation within the wall structure.
It is also possible that the edges of the sheathing will swell if moisture comes in contact with them. This requires installers to take care to prevent edges from getting wet before they are taped, potentially a real challenge during inclement weather.
Swelling may also occur when areas are torn, punctured or broken off during construction. It is possible that damage to the rigid foam boards will lead to unwanted air migration and condensation.
Moisture Problems That May Appear Later
Although air barrier sheathings come with a manufacturer’s warranty, that warranty is potentially voided by improper installation. During a busy construction season, a superintendent may be watching many projects, and it is possible that an installation error is missed. It is also possible that a building inspector might miss improper taping or damage that might compromise the air tightness of the system, thereby reducing energy savings.
Ultimately, improper installation may also lead to moisture buildup within the exterior wall system. The process is often quite subtle, and it may take many months to become evident. Should condensation lead to mold or mildew, a builder faces an expensive decision to strip a wall down to the sheathing in order to replace or repair it. Again, the manufacturer’s warranty may not help because improper installation typically voids warranties.
Advantages of Fully Adhered Barriers
By comparison, high performance, fully adhered moisture-resistive air barriers eliminate such challenges. Water is kept out while humidity/water vapor is allowed to escape. Because these barriers are fully adhered, it is much easier to install the barrier correctly with less chance for future problems.
DELTA®-VENT SA is an example of high performance well-engineered moisture-resistive air barrier that offers straightforward installation. The self-adhering overlaps lend themselves to proper installation. The membrane seals well around fasteners to preserve an air-tight seal. Also, there is little potential for sudden rains or unexpected delays during the construction process to compromise the barriers effectiveness.
The result is an air/moisture barrier that performs the vital functions for which it has been designed. First, it promotes energy savings by minimizing air migration. Second, it eliminates condensation in exterior walls – condensation that can lead to problems with mold or mildew that may threaten the health of occupants.
In conclusion, air barrier sheathings like ZIP System® features a built-in air moisture barrier that requires precise installation to be fully effective. Installation problems may even void the manufacturer’s warranty.
There are a number of potential installation problems leading to unwanted air migration and condensation in the walls. Should such condensation occur, the potential for mold or mildew is very real. At that point, remedies are typically quite expensive. Finally, an installation that is not air tight inevitably adds to energy costs.
Dörken delivers innovative, high-performance air and moisture barriers for commercial and residential construction sold under the DELTA® brand name. A North American manufacturer based out of Beamsville, Ontario, Dörken Products, Inc. is a subsidiary of Ewald Dörken AG, a leading European developer and manufacturer of waterproofing and drainage products sold worldwide. Dörken is known for delivering premium products while providing educational programs and full technical support. For more information, call 1-888-4DELTA4 (433-5824) or visit www.dorken.com.