A couple of months ago I had the sheetrock down on an attached unheated garage (I leave the boiler room door half open and it seems to warm the garage a bit, about 10 degree difference this winter between floors). Above the garage is two bedrooms. Now learning a bit more about moisture and vapors I hope I did not make a grave mistake. House being built in the 60's there was no insulation just some small piece of faced insulation thrown into the cantilevered spaces. I bought roxul unfaced comfortbatt r15 insulation and filled the spaces. Insulation touching the subfloor above (Hardwood floors above). The insulation filled about half the thickness of the joist and since I had extra r13 fiberglass faced insulation left over from a different construction job, I filled in the rest with the vapor barrier facing down towards the sheetrock that would become the ceiling of the garage. Also I filled the cantilevered spaces with two layers of roxul. However, now doing some research, have I created too tight of a sealed space to trap excess moisture between floors???