Grout that is stained, cracked, or separated can be seriously detrimental to the appearance of your tiled surface. It can also present a practical problem, as decaying grout could be allowing water to get behind your tile. For example, with ceramic tiling, not adding fresh, functional grout can leave you vulnerable to mildew and mold.
While it may seem like a complicated problem to fix, re-grouting a ceramic tile surface is a job that you can do yourself. With a little patience, you will have it looking like a professional job in just a short time.
Step 1 - Use the Right Type of Grout
Determine what kind of grout you're going to use. If you have a uniquely colored surface or existing grout, you need to make sure you match it up correctly. If you can, break off a loose piece and take it with you to a home improvement store so that you can hold it up next the samples. This will ensure that you get a good match.
Typically, if the space between your tiles is larger than 1/8", you'll want to use sanded grout. The sand gives the grout more strength and allows it to hold together better in the larger gaps. If the space is 1/8" or smaller, use an un-sanded grout. The absence of the sand will allow the grout to flow smoothly into the narrower space and you won't need the same tensile strength that is needed to fill larger gaps.
WARNING: Never use sanded grout if you have marble tiles. The sand in the grout will scratch the surface of the marble, and it cannot be repaired.
Step 2 – Clean the Existing Grout
Once you have selected the proper type and color of grout, it's time to get down to work. Before you do anything else, make sure the existing grout is clean. Use a commercial grout cleaner to make sure any soap residue, mildew, and everyday grime has been removed. Then allow it to dry thoroughly.
It may seem counterintuitive to clean the old grout you’re about to remove, but it is necessary as you move forward to remove the old grout.
Step 3 – Removing Old Grout
At this point, you need to remove all of the damaged, cracked, or crumbled grout. This is done using a grout saw, which you can pick up inexpensively at a home improvement store.
Use the saw to break away any loose material. It has a rough carbide cutting surface, which actually grinds out the grout more than it cuts it. You must make absolutely certain that there is no loose material left between your tiles. If there is and the saw pushes that excess into crevices you can’t see, it will start to fall out later underneath your new grout, and all of your hard work will have been for nothing. This is why cleaning is so important prior to removing old grout.
Next, take a wet rag and dampen the grooves where the grout is going to be applied. Since grout is actually a masonry product and not a glue, some moisture is necessary for proper adhesion. You want to make sure that you don't have puddles, but it is important that the area is damp before application.
Step 4 - Apply Grout to the Spaces
Once you've mixed the grout according to the manufacturer's specifications, you can begin applying it. Use a grout float to spread the mixture evenly over all of the surfaces that need to be filled. Once they are all full, go back over them with a wet finger to smooth each joint.
Take your grout sponge or a squeegee and wipe away any excess grout that’s bleeding over the edges and onto the ceramic tile. Try not to wipe over an area too many times, as you may disturb the grout that is drying in the grooves.
NOTE: Grout tends to shrink while drying, so as you wait for it to, dry don’t panic if you suddenly see gaps form. It's normal to have to go through two applications. When you are shopping, you may want to ask about non-shrinking grout; it could potentially save you having to repeat this step.
Step 5 - Seal the Grout
The grout needs to be sealed to help protect it against further stains and mildew. Do not underestimate this step. It’s possible that damaging conditions, such as longtime exposure to stains and mildew, are what wrecked your previous grout.
Sealer is available at the home improvement store and often comes pre-mixed with an applicator. Follow the directions and apply sealant directly and completely on your dry grout.
Step 6 – Finish Up
When the new grout dries, take a wet rag or a sponge and wipe any remaining residue off the face of the tiles. This will create a haze on the face of the tile. Allow that haze to dry, and then come back one more time and wipe it off with a dry rag. Underneath you will find your tile looks brand new, with a beautiful grout job to match.