Can and should are two important qualifiers when dealing with using caulking material in place of grout when tiling or repairing damaged grout. Caulk does fill in the space between tiles, but the product is not designed for use in this way. Professional tile installation includes the use of grouting mixes, and caulk does provide an important tool for professionals involved in installation and repair work, but caulk is not a substitute for grout.
The Function of Grout
Grout mixes Portland cement, powdered pigments and water. Mixtures also include sand, when the gaps between the tiles have a width of more than 1/8 inch. Grout functions to keep out moisture, hold tiles tight in place and provide a smooth finished-looking surface. Colored grout also adds a bit of design flair for certain tile installations. Properly installed grout prevents floor, wall and ceiling tiles from shifting during use, causing cracks and chips when tiles touch together. When grout fails, reinstallation offers renewal to maintain the ceramic or stone tile.
Purpose of Caulk
Caulking materials, designed for applications not requiring elasticity, seal out moisture, air and pests in stable joints of 1/4 inch or less. Caulk degrades over time and when exposed to wear, high and low temperatures, moisture and ultraviolet light. Caulking types include butyl, silicone, acrylic latex silicone, acrylic, latex, oil-base asphalt, glazing compound and caulking cord. The Michigan State University Extension program estimates the life of the various caulking materials between a year, for cord and oil-based asphalt, to a lifetime for glazing compounds.
The best repair strategy for failed grout, a term used to describe cracking or areas where the grout no longer adheres between the tile spaces, includes removing the grout and replacing it with new grout. This requires use of chisel hand tool or aan oscillating hand tool with a grout removal accessory to remove the grout. Work evenly with the hand or oscillating tool by sectioning off quadrants of tile. Once the spacing between the tiles is clear, use a vacuum to clean out grout chips and dust. Mix new grout and apply with a trowel and sponge off any excess. Allow the tile to dry, also called curing, and apply appropriate sealer to the grouting. This provides a long-lasting method for failed grout.
Disadvantages of Caulking as Grout
Caulking used as quick fill for small sections of failed grout or finishing a tile installation has great appeal. The caulking application takes little time, provides an inexpensive option and dries in a matter of minutes, as opposed to the time required to cure grout by drying and then sealing the filler. All of the apparent advantages of using caulk over grout, however, fail to consider that the caulking application for large areas has major disadvantages. Caulking discolors and the material quickly cracks after constant exposure to moisture-and-drying cycles. Caulking also decomposes allowing water access into the space between the tiles. Most importantly, caulking offers little stability to hold tiles in place, particularly in floor-tiling applications, leading to cracked and chipped tiles.