I have recently purchased an 85 year old 2 1/2 story colonial, with lath/plaster. Being that old you know there is no insulation. I want to remove all from the outside facing walls (from the inside) exposing 2x4 studs and install R13 faced insulation. Started on the second floor and looked down the studs and it looks like it goes all the way to the first floor. Can I inject/spray a fibrous insulation down the cavities between the studs and not be concerned about a thermal break problem? Or is this entire insulation thing a non beneficial endeavor?