Re: insulating a converted garage ceiling
Howdy ever think of getting a byuilding permit an then meeting the code required techniques? This might serve you well. Otherwise without the climate your in or the attic space ect. cannot help much start first in determining what insulation is in the rest of the house, how do you plan on venting the garage / addition roofing? Might want to bet some bids and read up on building additions- great books on it at most libraries.
Any an all of my comments are just my opinion and not to be confused with facts.