How To Professionally Regrout a Tile Shower
By Troy Cantini
When areas of grout look moldy, yellow and discolored then this is an indication that the rest of the grout is also in poor condition. The damaged grout may not look too bad from the outside but what you are not seeing behind the tiles in the walls can be a dangerous situation.
Over time water will make its way through the weakened grout and start accumulating in your walls. Eventually mold and mildew can grow in your walls and then can start eating into your wall joists and can cause serious problems. Additionally the moldy walls can attract ants and termites into your home.
The best way to prevent your shower from failing and causing excess damage to your home is to regrout your shower. Regrouting a tile shower is a difficult task but can be done by many industrious DIY type homeowners. You should only attempt to regrout a shower with narrow grout lines that have unsanded grout in them. You can read here about the many distinct differences between sanded vs unsanded grout. If you have sanded grout then you may want to consider cleaning the dirty grout and then colorsealing the grout to restore your grout back to like new condition. When regrouting a shower you should consider replacing any broken or cracked shower tiles while you are doing the regrouting procedure.
Before you begin regrouting your shower you should have all of your tile shower regrouting supplies purchased and ready to go. The first thing that needs to be done before regrouting a shower is to remove all of the old dirty and moldy grout and caulk in the shower. Removing the old caulk can be done with a plain old razor blade scraper tool. Just scrape away and remove all the old caulking as much as possible. It also helps to have some isopropyl alcohol to help in removing the old grout and cleaning the tile surface where the old caulking was. For extremely hard to remove caulk some acetone can be used to help soften the caulk up and remove it.
After you have removed all the old caulk then it is time to remove the old grout. There are many ways to remove grout but the best way is with a Fein multimaster tool or other type of oscillating tool using a diamond bit type blade. If you are going to be regrouting showers for a business the Fein Supercut is a much more powerful tool made for the serious home improvement contractor. If you are just a DIY homeowner then the Fein multimaster tool will work just fine.
The grout should be dug out at least 1/8th of an inch deep so that new grout can have a firm base to adhere to. Do not attempt to just apply new grout over the damaged existing grout Just applying new grout over the existing grout is called skim coating grout and this is a very bad practice. The new grout will not properly adhere to the old grout and there will not be a sufficient depth for the new grout to adhere to. Over time the new grout will start flaking and chipping away. Also the shower walls will still have mold in them and you will not be solving any of your moldy wall issues with this type of skim coating procedure. Always wear eye protection as well as a dust mask when removing shower grout with a multimaster type of tool.
Ensure that you hold the Oscillating tool steady and move it in a steady up and down motion along the grout lines. Use a steady hand to hold the tool so that the diamond blade goes in an up and down or side to side direction. You should hold the tool with two hands for better control so you do not slip out of the grout lines. Let the oscillating tool do the work and try not to put much pressure on the grout line. Let the tool do most of the work for you.
Removing all the grout in a shower can get a bit tiring on your hands and arms for some individuals who are not used to doing home improvement tasks. You may want to plan on removing the grout in sections over a couple days. It can also be helpful to remove the grout in one horizontal grout line followed by one vertical grout line so your hands and arms do not get as tired from holding up the tool in only one direction.
It is best to use the a round diamond bit for removing most of the grout in the shower. Do not put too much pressure on the diamond bit so that you do not wear a flat spot on the diamond bit. Also it is best to continually rotate the round diamond bit after every 15 minutes of use so that the diamond bit will wear evenly. If you take care of the expensive bit then you will be surprised at how good it works and how much use you can get out of a single diamond bit.
Do not attempt to use any carbide or off brand bit to remove the old grout. These bits will not last very long at all and they also will not grind away the grout easily like the diamond bits can.
For removing the grout along the corners and in tight spots a sickle or segmented diamond bit can be used. The sickle and segmented diamond bits allow you to remove grout out to the edges of adjacent tiles without damaging the adjacent tiles. The segmented diamond bits are good in that they can remove large areas of grout in the middle of the shower and also allow you to remove grout in the corners and in tight spots.
You can also use a utility knife to remove the grout in the edges where the Fein tool can not reach. A good quality utility knife is an essential tool in any regrouting procedure. A utility knife with a quick release button is helpful so you can quickly and efficiently replace the dull utility knife blades. This will save you time and energy without a lot of down time spent replacing the utility knife blades. A good quality utility knife can also help you to quickly cut out the old caulking prior to removing the grout.
Make sure to clean out all the old grout from all the grout lines. You do not want to have loose grout sitting in the grout lines and you want to be sure that all the grout got removed from the grout lines. A toothbrush or other type of grout cleaning tool brush works best to clean out the old grout from the grout lines. You may find that there is still some grout left on the edges of the tiles and this excess grout can be chipped away with a utility knife or other type of razor blade scraper tool.
Inspect all the grout lines to make sure that you have taken out at least 1/8" of grout so the new grout will have a firm base to adhere to. Ensure that no bits of grout are left in the grout lines by vacuuming all the grout lines with a shop vac. You should use a dust filter in the shop vac to avoid blowing dust out of the shop vac.
It is a good idea to allow you shower to dry out for a few days to ensure that your shower walls are dry before applying the new grout. A fan or dehumidifier can be used to assist in drying out your shower. If you try to apply grout to a wet shower wall the grout will not set properly and can look yellow or discolored in the grout lines. Also by drying out your shower wall you will be killing all the mold and mildew in the shower walls while the grout has been removed.
Ensure that all of your grouting materials are ready and you have all your preparations done before you start applying the new shower grout. This includes having a clean bucket of water and a sponge ready to clean up the grout. After all your prep work is done then it is time to mix and prepare the grout.
Use only dry powdered cement based grout for your new grout. Mix the grout to a peanut butter consistency. You should be able to be able to grab the grout out of the bucket without having it ooze out between your fingers. Follow the manufactures instructions when mixing the grout and it is very important to not have too much water mixed in with the grout. Watery grout will not set properly and will be weak soft grout that will not last for a long period of time.
Ensure that the grout is thoroughly mixed especially when using colored grouts. You want to make sure that you spread the color evenly throughout the grout. Mix the grout to a nice even consistency and you may need to add some more grout or water to get the consistency just right. You should be able to pick u a glob of grout without having it ooze out through your fingers. You can see a picture of correct grout consistency below.
Apply the grout with a rubber float and force the grout deep into all of the grout lines. Forcing the grout deep into the grout lines will ensure that there is good coverage of grout in all of the grout lines. Only apply grout to one small wall at a time. You do not want the grout to dry hard before you clean it with a sponge. For larger walls you may have to apply the grout to only one half of a wall at a time. Do not apply the grout to the entire shower before trying to clean the excess grout with a sponge. This is a common DIY mistake and the grout will become impossible to clean up and remove and can ruin the shower. Fighting with hardened grout and trying to remove it off the face of the tiles is no fun so it is better to only apply grout to small sections of the shower at a time.
After you have applied the grout to one section of the shower then wipe the tiles clean with a sponge. Using a damp sponge only wipe a small area before rinsing out your sponge in your bucket of water.
After you have wiped an area clean and the grout lines look straight and even then do not go back and re wipe the area with the sponge. Using too much water will weaken the grout and can also take the color out of colored grout. Just keep moving on until the whole area is cleaned and the grout lines look straight and even. You will see a grout haze form and you will need to go back later to clean up the grout haze on the tiles.
After you have cleaned up all the shower tiles then go and clean up the grout haze from the tile surfaces. Use a paper towel or cheese cloth to wipe away the grout haze. Do not leave the grout haze sit overnight because it can be extremely difficult to remove. Usually by the time you are done cleaning the excess grout with the sponge and have allowed the grout to sit for 30 minutes then you can start to remove the grout haze off the tile surfaces. Also at this time you can also inspect all the grout lines to ensure that you have not missed any spots and the grouting job was done correctly. If necessary apply small bits of grout to any areas of grout that were missed when applying the grout.
You should allow the grout to dry for at least 48 hours before you seal the grout and caulk the shower. It is best to seal the grout before applying the caulk in the shower. This will ensure that all of the grout gets sealed and the sealant does not damage the caulk. The best way to seal shower grout is with a brush type grout sealer applicator tool. Only do one wall at a time so that the sealer does not dry on the tiles. Ensure that the sealer totally saturates the grout lines. You may want to go over each grout line a couple of times to ensure that the sealer has totally saturated into the grout lines. Let the sealer soak into the grout for at least 5 minutes to ensure that the grout sealer has penetrated deep into the grout lines.
When the grout sealer has soaked into the grout lines then you should wipe the tiles clean with paper towels to remove any excess sealer. Inspect the tiles to ensure there are no streaks or sealer residue left on the tiles. If necessary you can apply some extra sealer to the tile surfaces to reactive the sealer to remove any excess sealer residue or streaks that were caused by the grout sealer.
You should use only 100% silicone caulking like Laticrete Latasil Caulk or GE silicone II sold in home improvement stores. 100% silcone caulk will not allow mold and mildew to grow it and will last for a long period of time. To apply silicone caulk it is best to tape off all the edges of the tiles 1/8" away from the tile edges to get a nice even bead of caulk. Remove the tape and smooth the caulk over with your fingers to get a nice even caulking joint. You can read more about how to recaulk a shower here.
After you have recaulked you shower then you should allow at least an additional 24 hours for the new caulk to cure before using the shower. You will be surprised at how much better you shower will look after you have properly regrouted your tile shower.
Regrouting a tile shower is a laborious messy and time consuming job. The time and cost it takes the average DIY homeowner can easily be justified in hiring a professional tile and grout restoration contractor. You can read some valuable information about how to hire a tile regrouting professional at our contractor information page here.
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