Can You Put New Grout on Top of Old Grout?


Your bathroom floor tile has come loose, so you want to put some grout between the joints before one of the tiles falls out. When you go to further inspect the joints, you realize that some grout remains, although it’s not much. Can you just squeeze out some new grout over what’s already there?

To apply new grout over a joint, you need to first remove the old grout instead of putting new grout on old grout. The materials in the grout must develop a bond between one tile and another, which isn’t possible if there’s already leftover grout. With a grout removal tool, you can scrape free the remaining grout and start anew.

In today’s post, we’ll further elaborate on what happens if you try to put new grout on top of old grout. We’ll also explain, step by step, how to remove that unwanted old grout. By the time you’re done reading, you’ll feel ready to tackle that bathroom tile issue! 

Why Shouldn’t You Put New Grout on Top of Old Grout?

If you buy a quality grout, then it could last as long as 12 to 15 years. A cheaper product or misapplying the grout initially can drastically reduce its lifespan, shortening it to about a year. You’ll know it’s time to replace your grout if the lines begin to crumble, crack, or separate. 

While it would be really easy and convenient to just be able to squirt out some new lines of grout over the old stuff, you simply can’t do that. Here’s why it’s such a bad idea.

Lack of Even Grout Layers

When you first applied grout to your bathroom tile years ago, were you very precise in how you did it? Unless every grout line is completely flat and even across, then adding new grout atop it will not result in an even application either. 

This is problematic for a few reasons. For one, the replaced grout is very obvious across your tiled bathroom floor compared to the areas that still have the original grout. Also, the new grout could dry thin in areas or thick and lumpy in others, which is quite unattractive. 

The New Product Could Separate or Crack Off

Grout is typically only sand, cement, and water. If you’re working with epoxy grout, it’s a bit more forgiving, but you have to think about what comprises grout when you’re applying it. Trying to patch up thin separation areas or cracks on either side of the grout line could cause the new grout to cure off to the side. 

If it doesn’t separate, then it might easily snap off because the grout failed to fill the original crack. In both these situations, the work you’ve done was pretty useless, as none of your new grout remains and your old grout is still cracked or loose.  

Water Damage Is More Likely  

With the original grout damaged and the new stuff not adhering properly, what do you think will happen if this tile gets wet? Water can seep into the tile, wreaking havoc. Depending on how long this issue goes unchecked, water damage can accumulate across the bathroom, especially if your old grout is near a shower or tub. 

Choosing a Grout Remover

It’s quite clear to you now that to truly patch up your loose bathroom tile, the old grout must completely go. How do you remove what remains of the grout in your bathroom? You need a grout remover tool for the job. There are several such tools, so let’s go over each of them in more detail now.

Angle Grinder

The first tool you might choose is an angle grinder. You’ll also hear of this tool being referred to as a disc grinder or side grinder. Intended primarily for grinding, hence the name, the handheld angle grinder can polish surfaces, grind down steel, remove paint or grout, and even cut tile.

Manual Grout Remover

If you’d rather skip the power tools, a manual grout remover is a suitable solution. This tool includes a blade and an ergonomically-designed handle. You angle the blade at the old grout and then push it up and out. 

Since you’re doing all the work yourself, you’ll need to put a good deal of elbow grease into using a manual grout remover. That’s why we’d only suggest this tool if you have just a bit of grout to remove. 

Rotary Tool

Switching back to power tools now, a rotary tool is small and includes a motorized tip that rotates very quickly. You can rely on a rotary tool for jobs like polishing, honing, sanding, and grinding. It’s also handy for getting rid of that old grout. 

Reciprocating Saw

A type of power saw, reciprocating saws can cut back and forth via pulling and pushing movements. Most favored for household demolition as well as remodeling, a reciprocating saw will slice through many a tough material, among them nails, PVC, metal, wood, and grout. Just make sure you use this tool carefully, as its destruction potential is high! 

Oscillating Tool 

Your last option is what’s referred to as a multi-tool or an oscillating tool. Yet another power tool, an oscillating tool can move back and forth, or oscillate. The various blades of an oscillating tool make it suitable for polishing, grinding, scraping, cutting, and sanding. 

How to Remove Old Grout

With your grout removal tool at the ready, it’s time to get started taking out that old grout! Here are the steps to follow.

Step 1: Make Sure You’re Using a Grout Blade

If you’ve selected a power tool for removing your old grout, double-check that the tool is outfitted with the right blade for the job. Anything other than a grout blade could be too strong, causing you to damage your expensive bathroom tile. 

Step 2: Go Lightly

Power tools don’t have to operate at full throttle. To start, use your grout remover on a lower speed or power setting if possible. If you can’t do that, then go with a lighter hand. This is again to ensure you work precisely and avoid cracking your tiles. 

Step 3: Switch to a Manual Grout Remover

As cool as power tools are, you probably won’t remove all traces of grout with one. That goes for everything from an oscillating tool to an angle grinder and even a reciprocating saw. By that point, you’ll want a manual grout remover to scrape out what’s left.

If you only bought a power tool to rid the old grout from the tile, then a flathead screwdriver can work as a makeshift manual grout remover in a pinch. 

Tips for Applying New Grout

Woohoo, the old grout is gone! Now you’re finally free to add some new grout. Before you get to work, make sure you keep these tips in mind. 

Select a New Grout Color That Closely Matches the Old One

You painstakingly scraped out your old grout so the new stuff wouldn’t stand out too much. Don’t discount all your hard work by choosing a grout color that’s not complimentary to what’s already in your bathroom. The colors of grout include:

  • White
  • Platinum
  • Silver
  • Gray
  • Stone
  • Slate
  • Linen
  • Wheat
  • Beige
  • Terra cotta
  • Latte 
  • Coffee

There are usually some pretty subtle differences from one hue to another. If you need gray grout then, you don’t want to accidentally end up with platinum grout. To prevent that from happening, we recommend you take a picture of your bathroom floor in natural lighting, ideally daylight. Overhead fluorescents can tinge the color of the grout, yellowing it somewhat.

Then, take your picture to the store and buy a color of grout that’s the closest match. We wouldn’t suggest you do online shopping here, as it’s often hard to gauge what the color will truly be from an Internet photo. 

Work with the Right Tools

Like you didn’t just choose any tool for removing the grout, the same should be true of applying the new grout. A grout float is the top pick for the job, hands down. What is a grout float, you ask? This tool almost looks like a trowel, but it’s made for pushing grout in the space between tiles. Try to buy a rubber grout float with a hard edge for best results. 

Know the Correct Angle to Hold Your Grout Float

How you hold your grout float as you work is very important. There are two angles you’ll use, 45 degrees and 90 degrees. When you’re first applying the grout to the tile, you’ll hold the float at the 45-degree angle. Later, when you sweep the grout into place, switch to a 90-degree angle so the grout gets in the gap between tiles. 

Start Small

You can re-grout your entire bathroom floor in an afternoon, as the project should take between two and three hours. That said, you don’t want to apply grout all over the floor and then sweep it into place bits at a time. The grout you applied will dry in areas before you get to sweep it, which is no good. Measure an area of your bathroom floor that’s three by three. When that area is done, move onto the next three-by-three area. 

Clean Away Grout Haze

Even if you try to work as carefully as you can, grout will always end up on your bathroom tile. If it does, you’ll likely see what’s known as grout haze. This is the light streak of grout residue that can form over the tile. 

Before the grout fully dries but while it’s still fairly hardened, grab a sponge, dampen it, and then clean the tiles. Wipe circularly to remove all the grout haze. Only clean to the edge of the tile, leaving the grout dry and intact. 

Don’t Forget to Seal

When your grout has finally finished drying, you might wish to seal it for more durability. Some sealers include a seal applicator, which you should use. If yours doesn’t have an applicator, then try a paintbrush, preferably a small one. 

If you smudge sealer onto the tile, clean it ASAP before it can dry. Then leave the bathroom for around 24 hours so a good seal can form over the grout.  

Final Thoughts

When your old grout cracks, remove the stuff before you attempt to apply new grout. This will give you a more even application that blends in with the rest of the grout, and more importantly, you can ward off water damage. Now that you know how to work with grout, cracks and gaps in your home don’t stand a chance! 

Geoff

Geoff Southworth is the creator of RealEstateInfoGuide.com, the site that helps new homeowners, investors, and homeowners-to-be successfully navigate the complex world of property ownership. Geoff is a real estate investor of 8 years has had experience as a manager of a debt-free, private real estate equity fund, as well as a Registered Nurse in Emergency Trauma and Cardiac Cath Lab Care. As a result, he has developed a unique “people first, business second” approach to real estate.

Recent Posts