We've done this application numerous times in southeastern PA with one subtle change, we use closed cell foam insulation directly against the underside of the roof sheathing. Open cell will continue t ... read more
If you don't want to loose ceiling height, you will need to remove the celing covering to gain access to the floor joist cavities.
A product we've had great sucess with is Roxul (http://www.roxul.com ... read more