“Your house needs to breathe” is a blatant lie
Talking with any experienced carpenter, you have probably heard the phrase “a house needs to breath, you don’t want to build it too tight.” This is common folklore that has been passed down from generation to generation. Your builder tells you he is doing something that is good for your home by letting it leak a little to get fresh air and allow the building materials to dry out. These concepts need to be addressed, but a leaky house is not the solution. You do want to bring fresh air into your home, but you should do it through a planned ventilation system. You also want to allow materials to dry out so you need to know the permeability of those materials and verify that you are not creating a surface that reaches dew point in the assembly.