If you’re doing tiling on fresh mortar, keep the level at the right depth. If it sinks, you need to back butter it.
No, we’re not talking about food, even though you may be forgiven for thinking that since we’re talking about back buttering – something often done with bread and butter to mop up stew from your plate. In this instance, we’re referring to tiling on a mortar bed and you find out that the tile sunk below where it’s supposed to go.
If this happens, you need to remove the tile completely and back butter. Slide something under that errant tile, generally something with a flat head, and gently apply leverage from one edge and take the tile right out from the mortar bed. Start gently in case the tile decides to just pop up. While that is rare, it can happen. In most instances, you’ll be prying up the tile to loud sounds of sucking, wet mortar. This is good. If you don’t get a sound when it comes up, something is wrong with the mortar mix, as in the consistency isn’t right or the tile wasn’t forced down hard enough.
To avoid finding out later the mortar isn’t quite right, check it first before you put it down. Here is another time saving tip as well. If you haven’t done something like this before, do a trail dry run first. It may save you a lot of grief later.
Once you have the sunken tile out, check the mortar. Is it spread out evenly? No? Then your consistency is way too dry. Sure you can add some water to thicken it up, but it’s actually better if you make a new batch and get rid of the dip in the floor. If you don’t want to do that, you can do a patch repair by sticking more mortar over the dry area under the tile and spread it out properly. Remember to do the furrows in the mortar in the same direction as the ones you already did. This is called back buttering and it gives proper adhesion and fills out those floor dips.
Also remember to put that pried up tile back down in the same direction and position it was in the first place. When you put it back in, gently pressure it with your fingertips, adding in a small twisting motion, and make sure the tile is well settled. If all goes well and you did it right, the other tiles won’t get bumped out of line and the one you just fixed will look great.