When grout is not sealed in time, grime and water can seep into it, causing cracks on your tiles and forcing them to break at a certain point. By sealing your grout, you get to prolong your tile surface's lifespan and minimize damage to a considerable extent.
Portland cement based grouts are particularly porous. Porous grouts attract water, dirt, oils, etc. While the tile industry does not require sealing, it is always recommended, especially in wet or high-traffic areas. Penetrating sealers are the most commonly used and offer high water, chemical and stain resistance.
If you are wondering how long you should wait between grout sealing on your high-traffic floors or frequently-used showers, the answer is at least once per year. However, The Grout Medic recommends sealing those areas every six months.
Most grouts, other than those that do not require sealing like epoxy grouts, are extremely porous. Grout is cement-based and the pores will literally take in all the stains, grime and bacteria that lands on them if they aren't sealed.
You can seal the grout the day after you applied it or 100 years later. If it isn't dirty, seal all three sides of the shower with a tile sealer or masonry sealer. That will make the grout water-resistant, if not waterproof, and help prevent the growth of mold and dirt.
Signs Your Grout Isn't Sealed or the Seal Is Deteriorating
If you notice your tile grout is changing color, specifically getting darker when it's wet, you can be pretty sure the seal is broken and needs to have some grout sealing reapplied by a professional.
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.
If you try adding new grout over your old grout, the new mixture will not properly adhere to the existing grout or tile edges, leaving your shower open to water damage.
The only type of grout that doesn't need sealer is epoxy, which is inherently pre-sealed. Grout sealers typically come in two forms-- spray-on sealers and applicator sealers. Applicator sealers are applied directly to the grout with a roller ball or a brush.
Some people will try to put a sealer on the grout joints, but that doesn't waterproof it. It doesn't work. It only makes it more water resistant.
Be sure to let your grout sealer dry thoroughly before testing a small area with a few drops of water. If the water beads up, you're all set! If not, you'll need to apply an additional coat of sealer to your grout. Most grout sealers take 1-3 coats for best results.
Sealing Grout With an Applicator
With the applicator method, each grout line is brushed individually with a small brush and sealant. Since the surface of the ceramic tile is glazed, it is already sealed. Tile grout sealer needs to be applied only to the grout lines and nothing else.
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.
Grout sealers will break down over time, so you're going to have to reseal grout on a floor every three to five years. Shower grout should be resealed once a year. Always clean grout carefully before doing this resealing.
At this point you may wonder if a complete re-grout is necessary or if it would be possible to simply put new grout over old grout. The answer is, yes, it is possible to put new grout over old grout.
Highly caustic or acidic cleaners, like bleach or vinegar, will corrode and slowly destroy grout and tile finishes. You might be surprised how clean you can get your grout with just some hot water and a brush. With that said, if the grout is deeply stained, there are other effective grout cleaning methods to try.
On the other hand, leaving the grout for too long before wiping it will result in irreversible damage, such as when it hardens. Additionally, the grout may dry before you wipe it off completely, resulting in a thin 'haze' on the tile surface, which may be difficult to remove. Remember that grout hardens as time passes.
Pin holes, large holes, cracks or missing grout ruin the beauty and aesthetics of your showers. The missing grout spaces accumulate water and the cracks absorb moisture, further leading to mold and mildew breeding. Mold and mildew occur in places that are constantly damp.
The consistency of grout should resemble smooth peanut butter. It should be malleable but not dripping from the trowel when lifted. If the mix is too stiff or dry powder is visible, add more water.
If your grout is coming loose, or showing signs of cracking or crumbling, it means that your tiles are MOVING, due to a buildup of pressure under your floor. The pressure, caused by a lack of expansion lines, or an issue with the adhesive under your tiles which is causing them to shift.
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 first question that comes to mind is, “can you regrout over existing grout?” The answer is very simple; yes, you can regrout over an existing grout. Applying new grout over the existing grout is a basic home project that you can easily do yourself.