A cellular glass system for an outer surface of a pipe. An insulation layer surrounds the outer surface of the pipe. The insulation layer has an outer surface and an inner surface and comprises cellular glass. A foam fills an annular space between the outer surface of the pipe and the inner surface of the insulation layer and is configured to limit water intrusion into the annular space and attenuate sound. The system may also include another insulation layer and another foam layer between the two insulation layers.