A contractor recently installed a pebble tile shower floor. About a month after we started using the shower, we noticed hairline cracks in the grout that extend almost all of the way across one portion of the shower floor. The contractor's suggested "fixes" have me feeling a bit uneasy (quote from contractor: "I think we should barely open up the crack and then smash the grout into it.") Even though the cracks are hairline, I feel that they need to be fixed. What would be the best way to fix these cracks so that problems down the road do not arise?
Also, we suspect that the crack is at the location where the Wedi shower pan is meeting up with the regular tile backer board on the floor. After the contractor installed the Wedi shower pan, my husband and I realized that the pan was too small so we asked the contractor to make the pan larger. Instead of re-doing the Wedi pan to the proper size, he assured us that the shower floor could be extended by simply applying a waterproof sealant to the regular tile backer board. So the last 6" or so of the shower floor are flat and not sloped and not part of the Wedi shower pan system.