We renovated our upstairs master bathroom 2 years ago. We used 12X24 porcelain tiles. We opted for very thin grout lines, the grout is coming out and there is movement in the tiles. The contractor said he put a thick layer of cement underneath but to fix the problem he would have to remove the dining room ceiling and add support beams. Does seem like the best fix or should we remove the grout and re-grout.
- Grout joints in a 12x24 inch tile should be at least 1/8" wide otherwise the grout can't fill the joint as it should. If the grout joint is 1/16" or less then chances are that is part of the problem. If the floor has too much deflection that could be the problem or at least a contributing factor to the problem. There are building code standards and tile standards that state that the floor should not have deflection greater than L/360 (L stands for Length of the span). If the tile installer knew the floor had too much deflection then he shouldn't have installed the tile, which is stated in the standards. Sometimes the deflection might not be noticeable, but that much deflection shouldn't cause a problem unless the grout joints are too narrow. If the grout joint is wide enough to fill with an epoxy grout that may or may not help prevent the grout from coming loose. You have to remove the existing grout first before you install the epoxy grout.