Grout can crack when there's too much water mixed into the grout, which create tiny pinholes. When the grout dries, these pinholes make it easier for cracks to form in the grout. Too much water in grout can make the grout weaker. Grout can crack due to thinset (glue) that is applied over the mortar during installation.
Whether you have tile grout cracking on the floor or wall, there's an easy solution; caulking. Caulk is a material that is used to seal or fill gaps. The act of caulking, is simply taking the caulk and applying it to the grout lines.
Too Much Water or Additive
If the original solution is not mixed correctly, this can lead to cracked grout. As the grout dries, the water in the mixture will evaporate. Adding too much water or additive can lead to air pockets and make the grout weak. Thus, making it crack easily.
How Long Should Grout Last Before Cracking? Non-sanded grout coupled with successful application will help your grout last at least 15 to 20 years. However, this largely depends on how much attention you pay to its maintenance.
Water evaporates faster with high temperatures, low humidity, solar heating and high winds which causes the cementitious material to lose water early (before final set) leading to plastic cracking, which is evident by the appearance of these fine cracks within hours of application out to 72 hours.
Epoxy grout won't crack, shrink, or discolour, making it ideal for applying in wet areas, such as showers. It's also highly resistant to the harsh chemicals found in cleaning products. As an added bonus, unlike traditional cement grout, epoxy grout does not need to be sealed, due to its non-porous nature.
Those cracks are due to: 1) too much water in the grout, and/or 2) green lumber. 1) There is a natural tendency to add too much water to the grout mix, because the grout becomes easier to “work”. Each batch of grout is mixed in anticipation to immediate use.
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.
A number of cracks or having to patch cracks more than once on a floor means you need to phone a professional. If you see numerous cracks in the grout, it can indicate an uneven installation of your subfloor or a weakening subfloor. Not only may you need to replace the grout and tile, but you may need subfloor repairs.
As mentioned, silicone works well in places where shifts in pressure can cause your grout to crack. For most bathrooms, this means using it as a sealant for the joints of the shower tray and the bath.
Grout needs to be sealed. It's naturally porous and will stain easily. Most installers of tile floors do not seal them because grout has to cure first. It's something you should do to keep your grout looking its best.
Cool down the tile for grout application
Porous tile that is too warm will pull moisture too quickly from the grout, increasing the potential for future cracking.
The best line of defense and protection for your grout is to have it sealed. Sealed grout will not only get the protection it needs against crumbling, but it will also be protected against heavy staining as well. Your tile and grout need to be professionally cleaned before getting sealed for best results.
You can remedy this by using caulk to fill in the cracks and restore the look of the grout. First, remove all loose and cracked grout with a grout saw or Dremel tool. Apply the caulk gently to the cracks, smoothing it down with a plastic spoon. You can also wet your fingers and smooth the caulk by hand.
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.
This tile needs periodic maintenance; cracks can develop in the grout between the tiles, allowing moisture to seep through. To stop the leak and prevent further damage to the underlying plaster or drywall, you'll need to seal all the places where water can penetrate.
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.
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.
With humidity levels being equal, grout will generally dry faster in a warm room than it will in a cold room.
If allowed to dry too quickly, the grout will have a soft, chalky surface that absorbs water. As the water is absorbed, the grout swells, fractures and falls away. In either case, water reaches the drywall behind the tiles and destroys it.
All new grout should be allowed to cure fully before being sealed. Even if the grout appears to be hard, achieving the correct color will require time for excess moisture to evaporate.
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.
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.
Grout doesn't last forever. You can expect a lifespan between eight and sixteen years. Its lifespan will vary depending on how you treat your shower. Odds are, you have no idea when your grout was installed.