We are working on our new old house. The bedroom ceiling is solid but has cracks and does not have insulation above the plaster. The third floor does have flooring and it would be difficult to pull it up to add insulation between the joists. I would like to try adding rigid insulation board to the ceiling with furring strips between that I can use for screwing on drywall. The plan is to screw the wood through the old plaster and lath onto the joists, glue the insulation to the ceiling between the furring and then screw the drywall onto the strips.

Anyone done this? Problems I will encounter? Alternative ideas?
Thanks for your ideas.

 

So is the third floor conditioned or is this the attic?


Adding all that material to the ceiling is just creating a big mess by adding all the layers of material plus to get anywhere near the recommended R value you would be adding so much material that you would loose head room not to mention the drywall would not be attached to a structural board.

You should look into blown in insulation, they can install by drilling small diameter holes between the joists and filling each cavity!