Looking to get some information on how to insulate a room using room in attic trusses. The house was previously a flat roof and a room in struck trusses were installed over the previous flat roof decking/sheathing. There is currently no insulation between the homes ceiling and the roof decking/sheathing. On top of the sheathing is currently the remaining 8” of styrofoam insulation that sat below the rubber roof.
How do I properly insulate on on top of the previous roof decking/sheathing for both the downstairs and the new room in attic.
Also, I do i insulate the rest of the room in attic which would be the walls and ceiling.
Thank you for any help you can share with me so that I can help my parents.