Scott,
The easiest thing to do is check in the attic and look at the sheathing. If there is any mold growth, you can tread it with a proper mildewicide and make sure that the fan ducting is extended ... read more
John,
Are you referring to insulating the ceiling of the garage (i.e. cold floors above)? Will you be dropping the ceiling or are you looking for options with minimal disturbance?