insulation for sometimes heated garage
My garage is used as car storage and sometimes workshop. When it is used as a workshop I use a propane radiant heater (unvented) to take the chill off. The ceiling and walls are not insulated and are covered with blue board and plaster.Knowing that there would be little payback with drafty garage doors etc I was thinking about insulating above the ceiling (uninsulated crawl space above ceiling 2/6 joists 16 on center )to hold some of temporary heat in.Is this ok to do and what type of insulation to use, should vapor barrier be used,should vapor barrier go towards ceiling and am I creating any moisture problems.
Thanks for any response