An application of our StoneLite® exterior wall panels regularly requires sealing joints; especially in the U.S. In instances where joint sealant is necessary, we at Stone Panels, Inc. have a few suggestions to offer. The first of our recommendations is the use of joints that are three-eighths of an inch wide; along with an open-cell backer rod and silicone sealant.
The reason we suggest silicone sealant be used with our exterior wall panels is that it is resistant to deterioration because of ultraviolet rays or high temperatures. Deterioration is especially a concern for darker colored stone because the stone surface can reach temperatures above 160 degrees Fahrenheit (if directly in the sun), even when ambient temperatures are below 80 degrees Fahrenheit. The alternative of polyurethane sealants isn’t preferable for use with exterior wall panels because polyurethane will fail often at around 140 degrees Fahrenheit.
Another consideration when addressing joint sealant used with StoneLite® exterior wall panels is that the sealant supplier should conduct accelerated aging tests. Such tests help determine if sealant bleeding into the stone might occur. Likewise, we at Stone Panels, Inc. also suggest builders request the sealant supplier to recommend a primer that won’t bleed. It is also a good practice for the owner to require a sealant warranty from the supplier for bond-to-stone and against staining.
As an added note, in the case of interior wall panels, using joints which are one-fourth of an inch wide works just fine. Some designers want to use joints which are only one-eighth of an inch wide; and it’s possible to use joints of such a size, but it creates difficulty in installation. In the case of interior applications, an acrylic sealant can be used because moisture penetration isn’t a concern. The ability to use acrylic sealant is great for interior applications because it doesn’t stain the stone and it hardens better than alternative sealants.