Paint will blister up if surface is still wet after painting it as moisture is trying to escape.

Take your time to correct problems such as water/moisture/mold, etc.

A house that old, particularly if there has been moisture, could have a long history of insect damage.I good building inspector should be checking all of these things (and more).  

A little finesse or using a different plank will work it out.Should not be used in bathrooms, due to the high moisture and water contact probability.  

In addition to new vents we are also considering installing cedar planks on all three bathroom ceilings because it’s mold resistant and (hopefully) handles moisture better than paint.Does anyone have experience with this?

They can look for recent damage and do moisture tests.  

A whole property humidifier requires maintenance, is prone to repairs and increases risk of mold through higher levels of moisture.

Additionally, there is evidence at a number of windows of moisture penetration.

Kenneth,My wife and I lived out in York Harbor for years, beautiful state.Try a plastic barrel that actually seals, I have seen them with an o ring, hinge and clamp.This may keep the moisture out better than a metal bucket.

I just want to know what kind of sheeting I can put up there that will not rot or be subject to mold as that basement will always have moisture issues.