by Cory Robbins, CSI
When it comes to multilayered dry-joint rainscreen systems, designers face a potential loophole in the specification/installation process.
Should a leak occur in a rainscreen design, before or after the project’s completion, the owner is faced with a costly dilemma. The problem usually occurs when there are different subcontractors for the air and vapor barrier system and the exterior façade system—the opposing subcontractors tend to blame each other. For example, the air barrier installer may claim the work was watertight before the exterior façade installer drilled holes into the system. On the other hand, the exterior façade installer might defend the exterior system as a dry-seal designed to let water in, meaning it has no watertight integrity standards. Everyone at this point is looking for a material manufacturer to fix the problem. However, this does not happen.
Air barrier manufacturers do not warrant workmanship within their systems; only material failures are covered. Material failure is probably the least likely event to occur within these systems. Manufacturers of air and vapor barriers will replace the material—the least expensive part of the system—and sometimes pay for the labor to install the new membrane. The most expensive aspects of the repair, including the labor to remove old material and exterior façade components as well as the means and methods of installation, are not included in the warranty. At this point, the building owner has one option.
Owners are required to organize and participate in meetings with the architect, general contractor, and owner’s representative, as well as exterior façade and air and vapor barrier subcontractors. The discussions take place over several meetings while the building continues to leak. If a resolution cannot be negotiated, the project follows the worst-case scenario and gets embroiled in a legal case—the problem will not resolve for many years. Sadly, this is standard practice in the industry.
Specify the solution
There is a solution to this problem, but it must be a proactive approach to the rainscreen façade. Architects must incorporate the solution into the specifications even before the project is bid. The concept requires the air barrier specifications to be the responsibility of the exterior façade installer/subcontractor. This allows the contractor to have a 10-year workmanship warranty for the water integrity of the wall. Since the air and vapor barrier is the weather barrier, this solution forces the exterior façade installer to be responsible for any leaks within the system, whether they self-install the work or subcontract it to another professional.
The specification language covers the owner and the architect alike by imposing coordination and detailed shop drawings to accommodate both disciplines. This creates a united team that can provide a leak-free rainscreen wall system for 10 years.
This proactive solution can be included as an ‘Add Alternate’ in the specification documents to allow the bidding exterior façade installers to place a price tag on the warranty. The owner can then decide to accept this alternate or be responsible for the façade.
This approach is not new and has precedence in the curtain wall and roofing industries. Many connected disciplines are included in these sectors to allow for complete coverage and associated warranties.
The curtain wall industry is responsible for all caulking within their system. The decision to self-install the caulking or subcontract to another vendor is decided by the curtain wall installer. The industry has also accepted this must be within their scope and responsibility.
The roofing industry follows the same ideology. It requires all copings, gravel stops, pitch pockets, counterflashing, welded vent covers, and various sheet metal items to be provided by the roofing subcontractor so as to maintain the specified warranty coverage.
Only the owner can decide the value of a leak-free façade for 10 years. Water/moisture infiltration is the number-one enemy of any building and this proactive approach is the protection.
Here is an example of the warranty language being used by architects in the mid-Atlantic region. Design professionals have the ability to incorporate the below language or adjust their specifications to allow for the same coverage:
Special Building Enclosure Warranty
The installer of the exterior panels shall provide a (10) year warranty covering all leaks that directly result from the defective material or defective workmanship supplied or performed by installer for both the air and vapor barrier and the exterior panels.
Should the exterior walls develop any such leaks during the warranty period, the installer’s sole obligation shall be to furnish necessary materials and labor to repair the affected area and return it to a watertight condition.
All removal of overburden and access to area is to be included in warranty. Warranty must be provided by a single source entity, which includes the waterproofing membrane, air and vapor barrier, and exterior rainscreen panels.
Cory Robbins, CSI, handles business development at EDA Contractors, which specializes on the exterior envelope of commercial, institutional, and industrial buildings. He holds an elementary education degree from Arizona State University. Cory can be reached at firstname.lastname@example.org.