In an ideal world, a tile installation lasts for generations. Human error, however, has a nasty way of popping up in projects, especially when they are of the DIY genre, where mixing and technique by the uninitiated can lead to mishaps. Take grout, for example, where pinholes, cracked areas, powdered joints and more are all simple mishaps that can thankfully be fixed without destroying the structural integrity of the installation.
Cracks are most commonly caused by floors that are not installed properly. When a tile begins to come loose and move, it vibrates, which sends cracks out into the surrounding grout joints as the tile works its way free. If a tile is loose it must first be replaced before it can be regrouted. Settlement cracks, on the other hand, which are due to the house naturally settling over time, are not signs of structural damage and can be readily filled in with a colored caulk to hide them from view, as well as fill it with a substance that shouldn’t crack out with further movement. Simply smooth the caulking over the crack with your finger to fill it.
Separation of the grout from the sides of the tile is generally due to one of two things: a tile that is moving with the expansion of the floor during summer months or a tile that is moving as a result of the house settling. Separation issues differ from cracks in that the joints may or may not crack beyond the individual tile, but instead separate from the side of the tile in a clean, straight line, only cracking across any intersecting grout joints that run perpendicular to the grout line of separation. Colored caulk is the preferred method to fill separation areas.
Pinholes are evidence of too much air being mixed into the grout, usually because of not following the directions on the bag regarding “mix by hand, or with a low-speed drill.” Instead, people often mix it with a drill on high, which whips air into the mixture; as the concrete grout dries in the joints, the air bubbles move to the top and pop, leaving behind pinholes in the grout joint surface. Either fill these with colored caulking, or clean the grout surface and regrout it with new grout to fill the holes.
If the grout is powdering out from within the joint, it’s a sign of excess water added to the mixture during installation. The cement and sand within the grout do not have enough substance to hold up over time, and thus revert to powder status. The only solution is to use a grout remover tool to completely clean the joint of old grout and then vacuum the powder out. From there, regrout the joint using new grout to fill the void. Make sure to water down the edges of the grout lines where old grout meets the new, to avoid the old grout sapping the moisture out of the new grout too quickly, leading to cracking and failed bond. For best results, cover the edges of the old joints with a latex additive to help further bond the new grout.
As grout ages, it oxidizes. As it oxidizes, it loses color and fades. The more time passes, the more it fades. Unless you are working with an installation that is a day or two old, any new grout you try to add on top of old grout will never match up exactly in color. This is also due to different ratios of pigments and water and cement between batches. Colored caulking also never dries exactly the color it shows on the tube, so test it in an out-of-the-way area before applying in a wide-open, visible space.