If your project specification calls for ASTM C-920 you are obligated to use a sealant that conforms to the specification. If you are not required to use a C-920 sealant, it is generally a good idea to use one anyhow. ASTM-C920 is a material specification that determines if a sealant performs at or above minimum acceptable performance levels as determined by sealant and construction industry professionals.
There are however, some very good sealants that do not conform to C-920. Developing a sealant involves a series of trade-offs between performance properties. Sealants developed for special applications may need to forego conformance to C-920 in order to concentrate on one or two critical performance characteristics at the expense of others.
It is important to work with our sealant professionals to insure you are selecting the correct sealant for each application.