You can regrout without removing all old grout by scraping out the top layer (about 1-2mm), thoroughly cleaning and drying the channel, and then applying a compatible, high-quality grout, like an epoxy or rejuvenation formula, ensuring firm packing and proper cleanup for a durable finish. While this saves labor, it's not ideal for severely damaged grout; for best results, always remove crumbling or moldy sections first for proper adhesion.
You generally should not grout directly over old grout for longevity and adhesion, as it often leads to cracking and peeling; instead, you must first remove a significant portion (at least 2mm) of the old grout, thoroughly clean the area, and then apply the new grout to ensure proper bonding and a lasting finish. Special rejuvenation grouts or epoxy grouts might require less removal, but scraping out most of the old material is the best practice for standard grout.
It'll also last longer on the bathroom or kitchen tile floor than in the shower for obvious reasons. So using a grout pen is great way to refresh the color of grout, or even change it from say white to black, but it's not a permanent fix. Granted you can paint over the grout again in few months.
4 of the Most Common Regrouting Mistakes
Avoid these 9 common grouting mistakes that could be ruining your tiling projects
You can apply new grout right over the top of the old grout. To do this, all you need is a grout removal tool. Use the tool to strike out the old grout, making sure the depth is at least 2mm, which is about the thickness of two dimes stacked one on top of the other.
Using the pen
It's ridiculously easy. Paint over the offending, grubby grout with the pen. That's it. The ink will cover the muck and restore the grout to its sparkling former glory.
As mentioned before, there are really only two ways to hide grout lines to give you the best looking results. They are: Make Your Grout Lines The Same Color As Your Tile. Make Your Grout Lines Appear Thinner.
The 1/3 rule for tile is a layout technique for long rectangular tiles (like wood-look planks) that recommends staggering joints by one-third of the tile's length, not the traditional 50%, to minimize lippage (uneven tile edges) caused by natural tile bowing, creating a smoother, safer, and more visually harmonious floor or wall. Instead of a standard brick-like pattern, it creates a diagonal or "stair-step" grout line, which looks more natural and helps hide slight height variations between tiles, making the surface feel flatter and more professional, especially under raking light.
Regrouting your bathroom tile is a relatively straightforward and approachable DIY home improvement project that can make a dingy bathroom wall look like new. Whether your grout is cracking and falling out or is simply discolored and in need of a refresh, regrouting can make a world of difference.
Light gray grout maintains a clean and fresh appearance while being more forgiving than white when it comes to stains and discoloration. Darker gray shades, such as charcoal, add depth and richness while effectively masking dirt and algae buildup.
Regrouting is the best option when tiles and grout begin to show signs of discoloration or the stains are so deep that they cannot be removed. As grout ages, it naturally deviates from its original color. If the white grout turns yellow or is covered with stains, you must regrout very soon.
Regrouting tiles is a straightforward job that most confident DIYers can tackle themselves. Take your time when removing the old grout to avoid chipping or damaging your tiles.
It is generally cheaper to regrout than to retile. Regrouting costs an average of $700–$1,500 while retiling costs $1,800–$5,000 on average.
The 3-4-5 rule for laying tile is a method to ensure a perfect 90-degree (square) corner, based on the Pythagorean theorem (32+42=523 squared plus 4 squared equals 5 squared32+42=52). You measure 3 units (e.g., feet, inches) along one wall/line from the corner, 4 units along the adjacent wall/line, and the diagonal distance between those two marks should then be exactly 5 units, confirming a perfect square corner for your tile layout. This prevents tiles from running crooked and ensures straight grout lines.
Clean's best way to clean grout is with the Mr. Clean Magic Eraser Bath with Gain Original Scent. Bursting with the fresh scent of Febreze® Meadows & Rain, it's powerful enough to knock out even the most-stubborn buildup on grout throughout your bathroom.
Generally, a well-applied grout pen can last anywhere from six months to a year before requiring a touch-up.
Since paint is not formulated to be applied to grout, it will not produce a great result. It will sit on top of the surface of your grout lines, and it will not last. Even if it looks okay in the beginning, it will end badly in a short amount of time.
Unsealed grout is susceptible to moisture penetration, which can lead to the deterioration of the grout itself. Over time, this degradation can result in weakened grout lines and tiles that may become loose or crack.
One of the most frequent grouting mistakes is improper mixing and application. Grout is a precise material, and getting this step right is crucial for its strength and adhesion. Incorrect Water-to-Grout Ratio: Adding too much or too little water can significantly weaken the grout.
Let the grout set for 15 to 30 minutes and then begin gently wiping off the excess grout with a clean, damp sponge.
Sanded grout is best for tile installation with wider joints 1/8” or more, as the grit creates a stronger bond that's less prone to shrinking or cracking. Unsanded grout works best for narrow grout lines less than 1/8” or with delicate surfaces like polished marble, metal, or glass tiles to prevent scratching.