Our home was constructed in the 60's with electric ceiling heat. In one room the ceiling is sagging from the weight of two layers of sheetrock. There appears to be no moisture in the attic and no signs of water entering the attic. How do I repair this problem? The house is unoccupied for about 5 months during the winter. The electric ceiling heat system is no longer in use as a heatpump is used for heating/cooling. We maintain the heat in the house when unoccupied at 60 plus degrees.