The 80 year-old house I'm restoring has a gorgeous tiled bathroom which apparently had a major leak for many years. Under the tiling is the cement which was used for the subfloor. The joists are all in fine shape, but have sagged in the middle due to water and/or weight. I would love to save bathroom floor tiling, which is classic 1920's style black and white. Under the bathroom is the diningroom. My two questions are these: 1) If I SLOWLY jack up the joists, will the cement subfloor likely fall apart, and 2) The bathroom is 14 1/2 feet by 6 feet. It is supported by 2x8 full length beams running lengthwise. After I level the floor, I want to use glue lams for joists so I won't have to use posts to support the weight in the living room. Will this work, and how would I best secure them to the frame?