By Paul E. Beers
I recently tried a Google search for the term “Wet Seal” and found it is a clothing chain for teenage girls that filed for Chapter 11 bankruptcy in January. I did not find any information about what I was looking for, which is a concept for sealing glazing systems in an attempt to halt water intrusion. I then searched several major sealant manufacturers’ websites and again came up empty. I found this to be very curious in that “Wet Seal” is a term I think most in the glazing and construction industry are very familiar with. Finally, I found the term defined by the Glass Association of North America (GANA) as Application of an elastomeric sealant between the glass and sash to form a weather-tight seal.
Wet sealing is a remedial process. It is not a part of new glazing system designs and should not be confused with “wet glazing,” which is when manufactured systems use sealants or tapes as part of their glazing detail. Wet seals are applied remedially when a conventional drainage system has internal leakage that is difficult to access or expensive to repair. In my experience with due diligence and investigations of water leakage in buildings, there are many buildings, particularly older ones, which have had some form of wet seals applied.
There are some important considerations when applying a wet seal. First and foremost is that a wet seal usually changes the design concept of a system from collecting and draining water to a barrier system where all water is repelled at the exterior plane. Once a wet seal is applied, if any water does enter the system, it is trapped inside with no provisions for drainage back to the exterior. Regular inspections and maintenance are very important to identify and repair any avenues for water entry. Water entry from surrounding areas, such as stucco, sealants, expansion joints, or even a roof leak above will also cause water to be trapped inside a wet sealed glazing system.
When applying a wet seal, it is critical to fully seal every possible avenue for water entry. This includes glass to metal, metal to metal and perimeter sealant joints. Each seal must be done properly and must tie in with each other. The finished system should basically be one continuous seal across the entire system. Since glazing systems experience very high temperatures in direct sunlight, silicone is the only material that should be used. Manufacturers’ recommended details for the type of silicone, joint design, profile and installation must be carefully followed.
The wet seal solutions we have designed include cutting back existing gaskets and applying silicone at glass to metal joints and using preformed silicone seals for metal to metal applications. We always involve sealant manufacturers to review and approve our details as being in accordance with their published recommendations. Manufacturers can also provide recommendations about needed accessories, surface preparation, proper adhesion and compatibility with abutting materials. Some manufacturers will provide up to a 20 year labor and materials warranty when following their strict guidelines.
For wet seals to work properly they must be designed and installed to be 100 percent perfect. If there are any deficiencies, water enters the system and becomes trapped, which can cause long term degradation of systems. Therefore, it is critical to proof the concept in the field and have a high degree of quality control during installation. We recommend that an in-place mockup of the repair be installed at project startup to include all typical conditions. The mockup up should be inspected and approved and then tested using ASTM E1105 Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, by Uniform or Cyclic Static Air Pressure Difference. After successful testing of the in-place mockup, installation should be carefully monitored by a third party and the sealant manufacturer must remain fully involved.
I consider a wet seal application to be a last resort after other considerations to repair and restore a system to the original design concept are deemed impractical or too expensive. Wet seals only are as good as their design and workmanship and last only as long as the materials continue to perform. While wet seals can be an effective and long lasting solution, they are basically a “band-aid” to correct problems that cannot be solved conventionally. Wet seals are often considered the easy, cost effective solution, but it really is “buyer beware” and all of the pros and cons should be carefully evaluated.