If there is one thing that we have learned in our many years as building contractors and home improvement journalists, it is that grungy tile grout is considered by many people to be the scourge of mankind. It is ugly and a pain in the neck to clean. And, recent studies by the U.S. Center for Disease Control report that certain types of mold can negatively affect one's health.
Appearance aside, tile grout serves an important purpose. It is a tiled surface's first line of defense against infiltration by water. It's the whole reason you installed tile in the first place - to protect the structural elements of your home from water damage. Although grout is only one part of the big picture, it's job is important. Cracks and gaps in grout are a sure sign that water is doing its one-two punch on the substrate which can be a real knockout on the pocketbook when it comes time to make repairs.
While grout helps prevent water damage, it is not the only source of waterproofing. A top quality tile installation will consist of a layer of straight and solid framing, a layer of building paper, a layer of mortar (we prefer floated mortar although precast mortar board is acceptable for a do-it-yourself installation), and finally the tile, grout and sealer. Therefore, if the tile or grout should ever develop hairline cracks (often not visible with the naked eye) there is a layer of protection below that will prevent damage. It is for this reason that we are strongly opposed to tile installed directly on wallboard -even if it is classified as "water-resistant." A shower constructed of tile glued directly to wallboard is, at best, a repair contractor's dream come true and, at worst, planned obsolescence.
Don't be a victim. Take control and you'll be money ahead. Start by keeping your grout clean. One of safest means of doing this is to use a solution that consists of one part distilled vinegar and one part water. Mix the two in a bucket and apply with a small brass brush or a toothbrush. The vinegar is a safe mild acid that will break down hard water deposits. For stubborn areas, spray the walls with vinegar and then cover the area with plastic wrap to keep it moist. This might be tedious work for a long-neglected shower, but will worthwhile.
If vinegar doesn't do the trick, try using hydrogen peroxide (the same stuff used on cuts). Here again, a bit of scrubbing will help cut the grease. If mildew is the problem, use the following solution: one-third cup of powdered laundry detergent, one quart of liquid chlorine bleach and three quarts of warm water. Add the bleach to the water first, then the detergent, and mix thoroughly. Even though the solution is mild, wear rubber gloves, safety goggles and have plenty of ventilation. For large areas, put the solution in a spray bottle and spray it onto the surface. Allow it to sit until the black mildew stains turn white (usually five to 15 minutes), but don't allow it to dry. Rinse with fresh water, dry and seal with a high-quality acrylic or silicone tile and grout sealer.
Once clean, if cracks are obvious or the grout is stained, discolored or just plain ugly, it's time to regrout. This process involves removing a small amount of the uppermost layer of grout and replacing it with a fresh new layer. Both appearance and waterproofing are improved.
When we first wrote on this subject over a decade ago, we recommended that a beer can opener be used to scrape away the upper layer of grout. Those were the days when it was easier to use our backs than our heads. Some years later we discovered a nifty tool called a grout saw - a small hand tool about the size of a toothbrush that consists of a handle attached to a small flat piece of steel covered with carbide particles. It is much more effective than the can opener and requires far less elbow grease. Now, thanks to modern technology, there is a lazy man's alternative - a power tool. A grout removal tool can be attached to a rotary tool to remove grout as effectively as your dentist grinds old fillings out of your teeth. Just be careful not to grind the edges of the tile.
Once the upper crust has been removed - usually about an eight of an inch, vacuum away all the dust and rinse with fresh water. Next, mix up a batch of new grout to a consistency of cake icing and apply it using a rubber grout float. Hold the float at about a 45-degree angle to the tile and, working in a diagonal direction to the tile, force the grout into the joints. Excess grout should be wiped off or "struck" using a damp sponge and fresh water. Wring the sponge out frequently to keep the tile clean and free of wayward grout. In short order, the grout will begin to dry and a haze will develop on the tile. This haze can be polished away with a piece of cheesecloth. The final step, sealing the grout and tile, can't be performed for about a week until the grout has had time to cure and dry. Use a high quality tile and grout sealer. We like one with a silicone resin. Epoxy is the best and should be used for added water resistance where tile is glued directly to wallboard or where extra stain resistance is needed, such as with kitchen counters.
