I own a home on a very busy street and the house placement borders the street, approximately 75 ft (23 m) from the curb. Traffic flow has increased over the past year, and I have tried all suggested and approved soundproofing wall systems with varied results. It would seem that a shotcrete product sprayed within a wall cavity would work great. My assumption is that I would need to insulate the outward face of the cavity enough to prevent excessive condensation and moisture buildup. This would certainly solve the sound problem (depending on the mass sprayed). Are there any suggestions or references you might be able direct me to?

A properly designed shotcrete composite wall system would certainly create a quiet atmosphere in the interior of the house. There are 3-D shotcrete wall systems on the market which use shotcrete on both the interior and exterior surfaces with a foam material in the center for insulation and vapor barrier. Attempting to do something like this to an existing structure would require a lot of analysis. Shotcrete is a method of placing concrete and adding shotcrete to an existing wall would significantly increase the weight of the wall and could overload the footings or impact other parts of the system. A structural engineer well-versed in residential construction should be consulted before attempting such a modification.