You may not need to remove most of the grout. It may be possible to apply new grout over old grout without removing it at some places. However, where the grout has deteriorated heavily through crumbling or become too dirty, it is best to remove it before applying new grout.
The grout should be dug out a minimum of 3mm deep (preferably deeper) so that new grout can have a firm base and a larger surface area of the sides of the tiles to adhere to. Do not attempt to apply new grout over the damaged existing grout.
Benefits of Putting New Grout Over Old Grout
Putting new grout over old grout is not as complicated as a complete re-grout as it does not require the removal of the old grout. It can also strengthen the surface to increase water resistance and make it less susceptible to impurities.
The short answer is, “no.” You cannot put new grout over old grout.
You don't need to remove all the grout, or even most of it, but removing the dirty grout on the surface gives the new grout something to which to bond. After all, grout primarily is just cement.
Grout haze is a byproduct of tile installation, during which the entire surface gets covered with grout. When the excess has not been properly cleared from the tile surface, what little that remains will eventually dry out, leaving behind a dull white film of just minerals.
Optimally, no more than 30 minutes should pass for the initial wiping off of excess grout. This process must be performed gently with a wet grout sponge during regrouting.
A drill is an ideal tool for removing the old grout from between your tiles, or a small multi-tool which you can attach a rotating blade to. Use your electric drill with the blade attachment to gently go over the surface of the grout to remove as much as possible, remembering to keep it well away from the actual tiles.
So, do grout pens work? The answer is yes. They are a great way to temporarily bring back the color and shine of dirty, stained grout between professional tile cleanings. They're easy to apply and dry fast, so you can return to enjoying your tiled surfaces in no time.
There are a few good reasons why you might want or need to remove old tile grout: The old grout might be moldy and beyond cleanable. In many cases, it is faster and easier to remove the grout than to clean it. The existing grout color is no longer pleasing to you, and you wish to change it.
Carbide blades are the go-to for most grout removal tools as they are both moderately priced and hard enough to handle the toughest grout. Tungsten steel blades are harder and pricier than carbide options but they work fast and are especially good for dealing with a lot of epoxy grout.
Fortunately, it's well within the range of the average do-it-yourselfer to remove and replace grout. Indeed, regrouting tile can restore lost luster and is well worth the time and effort.
You don't have to remove all of your old grout to apply the new grout. The new grout can be applied right over the top of the existing grout. You will need a grout removal tool, which is a small tool with a sharp blade capable of chipping away the grout.
ANSWER. ANSWER - It is possible to grout over existing grout if there is enough depth to do so. 1/8 inch depth may or may not be adequate depending on the type of grout used. A latex modified grout may work, but you have to properly clean the existing grout to ensure the new grout adequately bonds.
Re-grouting is more affordable than retiling as far as bathroom flooring options go. This DIY project can be done in about four hours, which makes it much faster than retiling.
The process is relatively simple and an entire shower regrout can usually be finished in about a day – even by someone who has never grouted tile before.
If you haven't kept up with grout maintenance, the once-white grout lines between your ceramic tiles may now appear gray, brown, or black. This discoloration is an accumulation of dirt, food particles, and—in the case of shower tile grout—mold.
Apply the grout in small sections.
A 45-degree angle is very important, and it refers to the angle at which you hold the float. Make sweeping arcs and work the grout completely into all the joints between the tiles. You can also use your grout float to wipe away excess grout as you go.
You can begin your haze cleaning as early as 24 hours after grout is dry up to 10 days after. It is not a good idea to wait longer than 10 days as it will make the job much harder. To clean grout haze all you need is some simple white distilled vinegar, warm water, a bucket, scrubby sponge, and a mop.