Sanded grout (with silica sand) works for most residential tile in joints 1/8 inch or wider. Unsanded grout is required for marble, glass, and natural stone because sand particles can scratch polished surfaces. Joints under 1/8 inch also require unsanded grout. Joint width drives the choice just as much as tile type does.
Quick Facts:
- Sanded grout contains fine silica sand that gives it body and prevents shrinking in wider joints
- Unsanded grout has a polymer-modified base and clings better to vertical surfaces and tight joints
- Marble, glass, and polished natural stone require unsanded grout to prevent surface scratching
- TCNA standard: joints under 1/8 inch use unsanded; 1/8 inch and wider use sanded
- Mixing sanded and unsanded grout in the same project is not recommended and compromises performance
Best For / Top Options:
- Standard Ceramic/Porcelain Tile — Sanded grout in joints 1/8 inch or wider is the industry standard
- Marble and Natural Stone — Unsanded grout required regardless of joint width to prevent scratching
- Tight Joint Installations — Unsanded grout for joints under 1/8 inch (marble, glass, rectified tile)
- Shower and Wet Areas — Epoxy grout preferred for best moisture resistance; sanded or unsanded cementitious requires sealing
- Color-Critical Projects — Epoxy grout offers the most color consistency; sanded/unsanded subject to variation
The key is knowing your tile type and joint width upfront. When choosing tile for your home, grout selection is part of that early conversation, not an afterthought. If you’re working with marble or natural stone, the Natural Stone Institute recommendations for experienced installers becomes critical. Understanding the full benefits of proper installation starts with decisions like these. Book a visit to Soleil Floors in Round Rock or Cedar Park to bring tile samples and discuss grout selection for your specific project.
Sanded grout is the right choice for the vast majority of residential tile installations. The exception that matters most is marble and other natural stone tile, where unsanded grout is recommended because the sand particles in sanded grout can scratch the surface. The grout joint width is also a factor — joints smaller than 1/8 inch require unsanded grout regardless of tile type.
Table of Contents
What Actually Makes Sanded Grout Different?
The name tells you what you need to know. Sanded grout contains fine silica sand mixed into the cement base. That sand gives the grout body and stability, which is what makes it work in wider joints without shrinking or cracking as it cures.
Unsanded grout has a smoother, polymer-modified base without the aggregate. It has a slightly sticky consistency that helps it cling to vertical surfaces and fill narrow joints without slumping.
The Tile Council of North America’s grout guidelines are clear on the dividing line: joints smaller than 1/8 inch call for unsanded grout, and joints of 1/8 inch and larger call for sanded. Use unsanded grout in a wide joint, and the grout will shrink and crack. Use sand in an overly tight joint, and it won’t pack properly.
Why Is Marble the Exception?
Marble is a cut natural stone with a polished or honed surface that scratches more easily than ceramic or porcelain tile. The sand particles in sanded grout are abrasive enough to scuff that surface during the grouting process, especially when the grout is being worked across the tile face with a float.
Marble is also typically installed with very tight joints, often 1/16 inch, because it’s manufactured to precise dimensions. That’s another reason unsanded grout is the standard choice for marble: the joint width alone would call for it even if scratching weren’t a concern.
The same logic applies to other natural stone tile flooring with polished or sensitive surfaces. Limestone, travertine, and glass tile all fall into the same category. The Natural Stone Institute recommends working with experienced installers specifically because natural stone has unique handling and installation requirements that standard ceramic tile does not. If you’re not sure whether your tile could be scratched by sanded grout, test an inconspicuous spot or ask before proceeding.
Does Grout Type Affect How the Floor Looks Over Time?
Yes, and this is where the choice matters beyond just the installation mechanics.
Sanded grout is more durable in wider joints because the aggregate prevents the kind of shrinkage cracking that causes grout to hollow out and fail over time. In a high-traffic floor with 3/16 inch joints, sanded grout will hold up significantly better than unsanded grout would.
Unsanded grout in a narrow joint on a polished tile tends to look very clean and refined. The thinner line without the textured appearance of sand reads differently from a design standpoint.
Color consistency is a separate challenge with either type. The TCNA notes that grout color variation is common and can stem from mixing inconsistencies, excess water, or uneven curing. Whites, blacks, and saturated colors are harder to control than medium grays and beiges. If color uniformity matters to you, epoxy grout is the most consistent option, but it comes at a higher cost and requires more installation care.
What About Grout in Showers and Wet Areas?
Wet areas are where grout choice matters most because failures are more consequential. A grout joint that starts to crack or hollow in a dry living room is cosmetic. The same failure in a shower can allow moisture behind the tile.
For bathroom remodels here in Austin and the surrounding areas, we discuss epoxy grout for shower floors and walls on most jobs. It resists staining and moisture penetration far better than standard cementitious grout, sanded or unsanded. The trade-off is installation complexity and cost.
If standard grout is being used in a wet area, sanded grout is typically the choice for floor joints at 1/8 inch or wider, and unsanded for wall joints that run narrower. Sealing either type before use in a shower is important. The TCNA’s guidance on grout cleaning and protection recommends sealing cementitious grout to reduce staining in both floor and shower applications.
One thing we see in Central Texas specifically is efflorescence, that white haze that appears on grout over time. Our concrete slab foundations sit on soil with varying mineral content, and moisture moving through the slab carries those minerals up through the grout and deposits them on the surface. The TCNA’s explanation of white residue on grout traces most of these cases back to moisture migration from below. A penetrating sealer on cementitious grout helps slow that process down.
Can You Mix Sanded and Unsanded Grout?
No. Mixing them together is not recommended, and the TCNA specifically cautions against it, particularly with marble and any tile that can be scratched. The sand content becomes unpredictable, and you lose the technical properties that make each type work correctly in its intended application.
If you have a project where some joints call for one type and others call for the other, use each where appropriate and keep them separate.
How Do You Know Which One Is Right for Your Project?
Start with the tile. Marble, glass, and polished natural stone: unsanded. Everything else follows the joint width.
If the joint is under 1/8 inch, use unsanded. If it’s 1/8 inch or wider, use sanded. If it’s over 3/8 inch, you’ll need a coarser, heavily sanded mix. Most residential installations fall in the sanded range. When choosing tile for each room in your home, the grout type is part of the conversation we have early, not an afterthought. The tile selection, joint size, grout type, and grout color all work together, and changing any one of them affects the others. Getting those decisions aligned before installation is a lot easier than trying to fix them after. Understanding the full benefits of proper tile installation starts with decisions exactly like this one.
Again, if you’re unsure, the best thing to do is bring a sample of your tile and a photo of what you’re trying to achieve. We can look at both and tell you what will work.
If you’re planning a tile project in Round Rock, Cedar Park, Georgetown, or anywhere in the Austin area and want guidance on grout selection, joint sizing, or installation approach, come see us. We’ve been doing this work for over 20 years and are known for tight joints and clean, lasting installations. Browse our tile flooring options at Soleil Floors or give us a call to get started.