As today’s building structures change their exterior façade, one of a number of growing trends is exterior metal wall panel systems and metal-capped parapet wall details. As with metal roofing systems, the builder must be concerned with the high amount of heat that is generated under metal roofing. The same rule applies when cladding the side walls or parapet walls with metal panels. The extreme heat buildup under these panels, and the effect that it has on the underlying materials, must be taken into consideration.
In general, self-adhered underlayments must be high temperature-rated for use under these roof and sidewall systems. This typically means that the membrane must be rated at approximately 225 degrees Fahrenheit or higher. Most building contractors will inquire what the membrane softening point is to help grade the options available on the market. The enormous heat generated under these metal panels can cause a breakdown of the membrane’s top film surface and/or cause the adhesive system to bleed out. As a result, the waterproofing properties can be compromised, which may lead to air, moisture or water to infiltrate into the building structure.