The vaulted ceiling is part of the roof. From the outside in, it’s shingles, roof boards, two by four rafters, probably fiberglass insulation of three inches or less, lastly sheet rock. I am going to ask if it is a good idea to:
- Fasten some ridged insulation board to the existing sheet rock?
- Then put new sheet rock over the ridged insulation?
- I like this idea best, but can you tell me if I could end up with a moisture problem above all of this?
If you like this plan, please recommend the type/ name of the insulation board.
First, I have to say we are not in the business of recommending any products other than reflective insulation and radiant barriers. That said, I would be more concerned with the added weight you would be placing on the system by installing another layer of drywall. You have a very difficult model to improve thermally. Without making major structural changes in the roof design there isn’t much you can do to fix your problem. If you are willing to remove all the current plaster or drywall, you could then install a radiant barrier across the face of the 2x4s, making sure that there is an air space between it and the fiberglass and then finish with drywall. This wouldn’t add any weight to the system and should give you some benefit. Whether it would be enough to warrant the work involved as well as the cost of materials I leave to you to decide.