How well does spray foam work with sound transmission?
Both 1/2 pound open cell and 2 pound closed cells are excellent buffers for sound transmission. However the 1/2 pound open cell absorbs sound somewhat better than closed cell. It works excellent it your near a railroad tracks or by a highway. Some builders will use it on interior walls between bedrooms and bathrooms. We have used around and underneath entertainment rooms and in between floors underneath joists.
