roof insulation

[creekside]

I have cut through the bathroom ceiling to install a light. I have removed insulation which has paper attached to it, the paper is on the bottom side of the insulation. How necessary is it that I replace the insulation with "papered" insulation. Also, I am installing new venting for the new exhaust fan. Is there really ever enough steam from the shower unit to actually condense in the vent and run back down inside it? Should the hole be sealed or is it merely enough to be satisfied with the cedar planks I will be putting up after all is installed.

[JD]

I have seen manufacturers use standard batt insulation with the paper backing, but that does not mean they haven't. If it were me, I would replace the insulation just as it was removed unless you can see a factory moisture barrier above the insulation. It could even be above the trusses, next to the roof.

Moisture barrier is handled differently in different areas due to different types of weather. A rule of thumb is, the moisture barrier goes to the warm side of the home during the most extreme weather conditions. There are exceptions, depending on how the roof ventilation and insulation system is designed. In older mobile homes, I will see the moisture barrier between the trusses and ceiling panels in hot climates and above the trusses in cold climates. Again, we are talking weather extremes, such as, hot summers and moderate winters being warm climates and cold winters with moderate summers being cold climates. A huge part of the US is somewhere between the extremes where there does not seem to be a definitive policy. Sorry, I imagine that does not help a lot.

I wouldn't think you could have a condensation problem in the fan or vent if the fan is turned on during showers and such.

I am not sure about your cedar plank question, but the fan should be installed to be flush with the finished ceiling. I don't believe true sealing of the vent-to-hole area is required, but it is not a bad idea. This could keep the fan from sucking dust out of the ceiling which can stain the ceiling around the vent.