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Mixing and matching weatherization materials can cause sticky situations

With the industry’s push to establish more moisture-resistant building envelopes, today’s builder has a wide range of water-resistant barriers, sealants, adhesives and building tapes from which to choose. Our advice? Choose wisely and read the guidelines, as chemical incompatibility between materials can lead to catastrophic product failures. Here’s a quick look at what to watch out for:

Self-Adhesive Flashings

According to guidelines from several manufacturers, self-adhesive flashings can have compatibility issues with sealants. Many asphalt-based flashings are not recommended for use with flexible PVC membranes and gaskets. Should the asphalt come into contact with flexible PVC, the plasticizers in the PVC will cause the asphalt to become liquid enough to flow, with temperature increases possibly accelerating the reaction.

Sealants and adhesives

Adhesives and sealants can have different chemical properties that are simply incompatible. Sometimes, the resulting problems won’t appear until well after the wall or window assembly is complete. Reactions vary from compromised adhesion to full-on meltdowns.

On a related note, many self-adhesive products also have strict installation temperature guidelines. We see the poor adhesion that results from installing flashing in temperatures both above and below the guidelines.

How to avoid problems

Ultimately, preventing incompatibility issues should be as simple as reading and following the manufacturer’s product guidelines and installation instructions. But even if you’re confident that mixing and matching products from two different manufacturers is OK, you should still test their compatibility before installation.

This can be a time-consuming option, of course, and may not lend itself to all climate conditions – as noted above, excessive heat can exacerbate problems. The easier option is to source your weatherization system components from a single supplier that has already tested products and guarantees their compatibility. This approach is at the heart of our FortiFiber® 1-2-3 Moisture Control System, which features a range of fully compatible WRBs, flashing, and sealants. Not sure where to start? Find compatible solutions here.

Contact a Henry weatherization expert for advice and support on your next job.

incompatibility window flashing melting

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