There are three types of adhesive failures that can occur over the lifetime of a shower system installation; adhesive failure; cohesive
failure, and substrate failure. When a joint sealant fails, it puts the entire installation at risk. The last thing you want to experience as a tile contractor is a callback from a good customer, so it’s important to be familiar with the correct type of sealant for your project. Even more importantly, you should have confidence that the trust you place in the product is absolutely warranted.
Joint Sealant Failures Aren’t Mysterious
Foam tile backer boards and shower pans are relatively new technologies in the building and remodeling industry, and so the overall application has been met with suspicion from “old school” tile setters. It should be no surprise that sealants are met with similar distrust, especially when the prescribed prep is to “glue” together all the underlayment panels. Not all adhesives are created equally - just ask the lady that used Gorilla® glue to style her hair. All sealants are subject to failure, depending on the
following types of conditions.
An adhesive failure occurs when the sealant just won’t stick to the surface. This indicates you aren’t using the correct sealant for the job, or the surface you’re adhering the sealant to isn’t prepared properly to promote sufficient bond strength. A cohesive failure occurs when the sealant cracks, leaving sealant on each side of the joint. This occurs when the sealant shrinks, ages or weathers poorly due to inadequate levels of UV inhibitors, the use of water-based formulations or formulations poorly suited for the application. Lastly, a substrate failure occurs when the adhesive and cohesive bonds are stronger than the substrate, thus tearing the substrate apart. This is the type of failure that is of high concern for installation mechanics because joint movement can be common in a typically constructed home. Substrates like GoBoard with industry leading foam core compressive and outer skin tensile strengths help prevent these modes of failure.
Trust Issues
It’s not unusual to have trust issues when it comes to gluing things together! This is where industry standards and testing for building products comes to the rescue. When using GoBoard® Pro Sealant, one needs to look no further than its ASTM C290 classification (ASTM C920, Type S, Grade NS, Class 25 or better). Let’s break it down. Type S means it’s a single component.
Grade NS means “no sag.” And Class 25 means it’s been tested and classified as “allowing up to 25% of joint movement.” With this designated certification, you can trust the bond between GoBoard Pro Sealant and GoBoard Tile Backer board because it’s been rigorously tested for flexibility, durability, and adhesion. In fact, a GoBoard joint sealed with GoBoard Pro Sealant produces seam
strengths that are 3 times stronger than a cement board joint while remaining flexible.
Trust, But Reinforce
You know the adage, trust but verify. There is no reason why you can’t be doubly certain to mitigate any possibilities of joint
movement failures. One popular method to both waterproof and reinforce joints is to use banding. You can do this using GoBoard Seam Fabric, which is a new light weight, point-bonded polyester non-woven, specifically designed to enhance the performance of GoBoard products.
A key benefit of using GoBoard Seam Fabric in your prep process is that it increases tensile strength and sheer bond strength at the
joints and provides superior adhesion between GoBoard Pro Sealant and thin set mortars without the need to wait for the sealant to skin over. Using only GoBoard Pro Sealant will give you 25% allowable joint movement, compared to 50% allowable joint movement when using the sealant and seam fabric combination.
A little construction science patience goes a long way, as does a product knowledgeable tile prep mechanic. There is also a secondary benefit to using GoBoard Seam Fabric. Once the thin set mortar cures, the bond to the sealant is tenacious. Prior to this, the sealant may smear while keying in your thin set. GoBoard Seam Fabric applied over GoBoard Pro Sealant greatly reduces this smearing from happening because it provides a highly bondable intermediary surface between the sealant and thin set, as each of them require more time to fully cure. You can trust this option. As you start to tile you can be confident that the bond grows continuously stronger as time passes.
To learn more about GoBoard Seam Fabric and how it can fortify your joints, especially between the walls and floor, or ceiling, visit https://www.jm.com/en/goboard-tile-backer-board/goboard-accessories/