Filled viscoelastic solids, or building joint sealants, are essential components of modern construction. They serve in the weatherproofing of buildings and structures by preventing moisture intrusion. The most important property is the ability to respond to imposed strain caused by temperature or moisture changes in the structural building components while maintaining the critical moisture/energy barrier properties. These materials are typically warranted for greater than 40 years. During this long service life, chemical and molecular changes within the sealant are accelerated by the weather and give rise to changes in the rheological and adhesive properties. While, ultra‐violet light, temperature, and humidity are critical to influencing the sealant changes within the environment, recent studies have shown that imposed strain on several different formulations of sealant during environmental exposure has a significant affect on the measured rheological properties. Cyclic strain on the sealant in the prese...