I'm about to hang new drywall over an existing celling that is drywall and plaster. The old ceiling has that popcorn look to it but with plaster so its to difficult to scrape off. Do I need to tape the new drywall since its s just a second layer? Will the seams still crack and separate with time? Thanks for any advise.

 

yes, you always tape the joints and corners no matter what.

 

Yep you always tape the joints/corners. The only time you wouldn't tape is if you were hanging 2 layers of drywall then the 1st layer wouldn't need to be taped....... unless it's a fire wall.