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Does it Stick? The Compatibility Component

As we continue to evolve in the built environment, what may be considered the minor details in such as window to wall, roof to wall and other flashings and attachments have become more critical. These details have also become more complex, often because of issues which are self-inflicted. One such issue is the question of compatibility and adhesion between enclosure components and the products utilized to complete these important details.

During my career, the primary question has been the generic “Does it stick?” While valid and important to understand whether Sealant X will adhere (stick) to Self Adhered Membrane Y, this does not go far enough. Do we know if they are compatible?

Essentially, compatibility can be simplified into the concept of ensuring that two products, components, chemicals, or other items can be in contact with one another or in close proximity without any long term negative impacts on one another. Adhesion may be fleeting, but compatibility is for the long haul. For those of you in a relationship, think about dating versus the long haul of a lifetime with one’s partner!!!! May not always be pretty, but does it work?

Adhesion is often top of mind, and certainly important, but I have been asked more times than I can recall for a compatibility test of a urethane sealant with the concrete deck being caulked. While they are compatible, and there is ample history supporting this, but the question is about the real need for confirming adhesion. This would typically be part of a QA/QC process in the field with a field adhesion test. Often this is an error in spec language or a misunderstanding of these terms.

While both are important, it is critical to understand the difference. An example is a silicone sealant and an EPDM glazing gasket. These may have only marginal adhesion, which may or may not matter depending on the application and the system. However, relative to compatibility, this can become much more critical. In Silicone Structural Glazing, compatibility of the tensile bead to the spacer is critical for long term performance, so full contact compatibility must be verified whereas at a perimeter gasket point contact level of compatibility may suffice.

A proactive approach is a must as we deal with the ever-changing world of our building enclosures. We deal with a multitude of products and technologies; urethane, silicone, TPO, EPDM, Self Adhered Sheets, silicone emulsions, Hybrids, PMMA, and the list goes on and on. From my experience, I would offer the following as a starting point to consider ensuring that you have both the adhesion and compatibility of your enclosure details covered:

  • Ensure your specification calls out for pre-construction adhesion and compatibility testing to be included in submittals.

  • As a sub-contractor engage with your material suppliers and review details and obtain this testing and/or confirmation prior to the mock up.

  • Build and test a pre-construction mock-up. Seeing is believing, and this is the time to find any issues, and seeing it all come together will help find those issues which don’t show up on a drawing.

  • Engage a third-party enclosure consultant on your team to help identify these potential issues early on and assist in reviewing mock-ups, submittals, and project installation.

  • Adhesion and compatibility, be sure to understand the difference and impact of both as they relate to the critical details in your enclosure.

Compatibility is the key to any relationship, and is equally important in how our enclosure components relate to one another and perform over the long haul.


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