Choosing the Best Grout for Your Tiling Project
After hours of browsing tile showrooms, comparing ceramic versus porcelain, and finally picking out the perfect pattern for your bathroom or kitchen, you might think the hard decisions are over. However, there is one more choice that can make or break the longevity and appearance of your installation: selecting the right grout. Specifically, the debate usually comes down to sanded vs unsanded grout.
To the naked eye, a bag of grout might just look like colored powder. But the difference in their composition changes everything about how they behave once mixed with water and applied to your tile. Using the wrong one can lead to unsightly cracks, scratched tiles, or grout that simply falls out of the joints over time. In this guide, we will break down exactly when to use each type, why the width of your tile gap matters so much, and how to avoid common mistakes during the application process.
The Short Answer: Which One Should You Use?
If you are looking for a quick rule of thumb to get started, it usually comes down to the width of the space between your tiles, known as the grout joint.
- Use Sanded Grout for joints that are 1/8 inch wide or larger.
- Use Unsanded Grout for joints that are smaller than 1/8 inch wide.
While this is the standard industry guideline, there are several exceptions based on the type of tile you are using and where it is being installed. Let’s dive into the details of each type to understand why these rules exist.
What is Sanded Grout?
Sanded grout is a cement-based grout that has been mixed with fine sand. The sand acts as a filler and a reinforcing agent. Think of it like the aggregate in concrete; it provides structural integrity and prevents the grout from shrinking too much as it dries.
Because grout is a cementitious product, it naturally wants to pull inward and lose volume as the water evaporates during the curing process. In a wide gap (anything over 1/8 inch), that shrinkage is very noticeable. Without the sand to hold the structure together, a wide joint of grout would crack, pull away from the edges of the tile, and eventually crumble. The sand particles lock together to create a sturdy, durable bridge between your tiles.
Pros of Sanded Grout
- Resistance to Shrinkage: The primary benefit is that it stays put in wide gaps.
- Durability: It is highly resistant to cracking and can withstand the pressure of heavy foot traffic on floors.
- Cost-Effective: Sanded grout is generally less expensive than unsanded or specialty epoxy grouts.
- Wide Availability: Because it is the most common choice for floor tiling, you can find it in an enormous variety of colors at any home improvement store.
Cons of Sanded Grout
- Abrasive Texture: The sand is coarse. If you use it on delicate surfaces like polished marble, limestone, or glass, it can act like sandpaper and leave permanent scratches on the tile.
- Absorption: It is porous. Unless it is mixed with an additive or sealed properly after curing, it can absorb water and stains.
- Difficulty in Tight Gaps: It is hard to force the sand particles into very thin joints (1/16 inch or less), which can lead to air pockets and weak spots.
What is Unsanded Grout?
Unsanded grout, sometimes called “non-sanded” or “wall grout,” is a smooth mixture of Portland cement, pigments, and water-retention agents. As the name suggests, it contains no sand. It has a much stickier, creamier consistency when mixed, which makes it ideal for specific applications where sanded grout would be too abrasive or thick.
Because there is no sand to hold the structure open, unsanded grout is prone to significant shrinkage. This is why it is restricted to very narrow joints. In a narrow gap, the shrinkage is minimal enough that the grout remains stable and stays bonded to the tile edges.
Pros of Unsanded Grout
- Non-Abrasive: It is safe to use on polished stones, glass, and mirrors without the risk of scratching the finish.
- Excellent Adhesion: It is very “sticky,” which is helpful when working on vertical surfaces like shower walls or kitchen backsplashes. It stays in the joints better during application without falling out.
- Smooth Finish: It provides a clean, refined look that is often preferred for high-end aesthetic designs.
Cons of Unsanded Grout
- Prone to Cracking in Wide Joints: If used in a gap wider than 1/8 inch, it will almost certainly crack and pull away as it cures.
- Fewer Color Options: While still available in many shades, the selection is sometimes slightly more limited than sanded varieties.
- Higher Cost: Per pound, unsanded grout is often slightly more expensive than sanded grout because it contains more polymer additives and cement to compensate for the lack of sand.
The 1/8-Inch Rule and Beyond
The standard measurement for choosing between sanded vs unsanded grout is 1/8 inch. This is the “magic number” in the tiling world.
If your tile spacers are 1/8 inch or larger, the bulk of the sand is necessary to keep the grout from collapsing. If you are using “rectified” tiles (tiles that are cut precisely to allow for very thin joints), you might be looking at 1/16 inch or 1/32 inch gaps. In those cases, the sand particles in sanded grout are actually larger than the gap itself, making it impossible to fill the joint properly. You must use unsanded grout for these precision jobs.
When to Choose Based on Tile Material
Sometimes, the width of the joint isn’t the only factor. You also have to consider what the tile is made of. This is where things can get a bit tricky.
Polished Natural Stone: If you are installing polished marble, travertine, or granite, you should lean toward unsanded grout. Even if your joints are 1/8 inch, the risk of the sand scratching the expensive finish is high. If you absolutely must use sanded grout for structural reasons on a marble floor with wider joints, you should test a small, inconspicuous area first or look for a “fine-sanded” specialty product.
Glass Tile: Most glass tile manufacturers recommend unsanded grout. Sanded grout can easily dull the surface of the glass or scratch the colored backing if the grout is worked into the joints too aggressively.
Ceramic and Porcelain: These are usually rugged enough to handle sanded grout without any issues. Most standard floor tiles are porcelain or ceramic and utilize 3/16 inch or 1/4 inch joints, making sanded grout the default choice.
Vertical vs. Horizontal Applications
Another layer of the decision-making process is where the tile is located.
Floors: For floor installations, sanded grout is almost always the winner. Floors take a lot of abuse from people walking on them, moving furniture, and cleaning. The extra strength provided by the sand helps the grout withstand these pressures. Furthermore, floor tiles are rarely placed with joints narrower than 1/8 inch because the subfloor can shift slightly, and wider joints allow for that movement.
Walls: For bathroom walls, kitchen backsplashes, and decorative accents, unsanded grout is very popular. Because you aren’t walking on walls, the grout doesn’t need the same level of structural reinforcement. The stickiness of unsanded grout also makes it much easier to apply to a vertical surface without it dropping onto the floor or your shoes.
A Note on Modern Alternatives: High-Performance Grouts
In recent years, the line between sanded and unsanded has blurred thanks to the invention of high-performance cement grouts and pre-mixed grouts. Some manufacturers now offer “all-in-one” grouts that contain extremely fine aggregates. These products claim to be safe for joints ranging from 1/16 inch all the way up to 1/2 inch and are often advertised as being non-scratching.
While these are excellent options, they are more expensive. If you are a beginner, sticking to the traditional sanded vs unsanded distinction based on your joint width is usually the safest and most budget-friendly way to ensure a successful project.
Maintenance and Sealing
Regardless of whether you choose sanded or unsanded grout, both are cement-based and therefore porous. This means they will soak up liquids, which can lead to mold, mildew, and deep-set stains.
Sealing Sanded Grout: This is a must for floors and showers. Wait for the grout to cure completely (usually 48 to 72 hours, but check the bag) before applying a high-quality penetrating sealer. This creates a barrier that keeps moisture and dirt on the surface.
Sealing Unsanded Grout: Even though the surface of unsanded grout is smoother and more compressed, it still needs to be sealed, especially in wet environments like a shower. This will keep your grout lines looking bright and prevent the growth of bathroom funk.
Common Mistakes to Avoid
Even if you choose the right type of grout, the installation process is where many DIYers run into trouble. Here are some of the most common pitfalls:
1. Using Too Much Water
When mixing grout, it should have the consistency of peanut butter or thick cake frosting. If you add too much water, the grout will be weak once it dries. Excessive water in the mix is the leading cause of “pinholes” and color shading issues. For unsanded grout, too much water makes it incredibly messy and increases the likelihood of shrinkage cracks.
2. Wiping with a Sopping Wet Sponge
After you apply the grout and let it sit for a few minutes, you have to wipe the haze off the tile. If your sponge is dripping wet, you will wash the pigment out of the grout and weaken the top layer. Wring your sponge out until it is barely damp. You want to clean the tile, not soak the joint.
3. Ignoring the Slake Time
Almost all cement grouts require a “slake” period. This means you mix the grout, let it sit for 5 to 10 minutes, and then mix it again without adding more water. This allows the chemicals in the grout to fully hydrate. If you skip this, the grout might not set correctly.
4. Applying Sanded Grout to Glass without a Test
Never assume your tile is tough enough for sanded grout. Take a loose piece of tile and rub some grout on the surface to see if it scratches. It is better to find out on a scrap piece than on your finished wall.
Frequently Asked Questions
Can I use sanded grout on my shower floor?
Yes, and you probably should. Most shower floor tiles are small (like mosaics) to provide better grip and to slope toward the drain. These small tiles often have 1/8 inch or 3/16 inch joints. Sanded grout will provide the durability needed for a high-moisture, high-traffic area. Just make sure to seal it well.
Is sanded grout waterproof?
No. Neither sanded nor unsanded grout is truly waterproof. They are water-resistant once cured and sealed, but they are still porous. The waterproofing of your shower or floor comes from the membrane or underlayment beneath the tile, not the grout itself.
Why is my unsanded grout cracking?
The most common reason unsanded grout cracks is that it was used in a joint that was too wide. If the gap was wider than 1/8 inch, the grout shrank too much as the water evaporated, leading to fractures. Another reason could be that the subfloor or wall is shifting, or that too much water was used during the mixing or cleaning process.
Can I put new grout over old grout?
You should generally avoid this. Grout needs depth to bond properly. If you just smear a thin layer of new grout over old grout, it will likely peel off or crack within a few weeks. If you need to refresh your grout, it is best to remove at least 1/8 inch of the old grout with a grout saw or oscillating tool before reapplying.
Does the color of the grout change the choice?
The color itself doesn’t change whether you need sanded or unsanded, but it can affect the appearance. Sanded grout has a matte, grainy look. Unsanded grout has a smoother, more plastic-like appearance. If you want a very sleek look with dark grout, unsanded is often preferred, provided your joints are thin enough.
Summary Table: Sanded vs Unsanded Grout
| Feature | Sanded Grout | Unsanded Grout |
|---|---|---|
| Joint Width | 1/8″ to 1/2″ | Less than 1/8″ |
| Best For | Floors, wide joints, ceramic, porcelain | Walls, backsplashes, marble, glass |
| Shrinkage | Minimal (due to sand) | High (can’t be used in wide gaps) |
| Texture | Coarse, gritty | Smooth, creamy |
| Cost | Lower | Higher |
Final Thoughts
Choosing between sanded and unsanded grout doesn’t have to be a stressful part of your home improvement project. By simply measuring your grout joints and considering the material of your tile, the choice usually becomes clear. Remember the 1/8-inch rule: anything wider needs the strength of sand, while anything narrower needs the smooth precision of an unsanded mix.
Take your time with the mixing and application process. A well-grouted floor or wall not only looks professional but will protect your home from moisture and wear for decades to come. Whether you are tackling a DIY backsplash or tiling a whole master bath, getting the grout right is the final step to a beautiful, lasting result.
