Subway tile installations are classic and versatile, but choosing between sanded or unsanded grout for subway tile affects durability, appearance, and maintenance. This guide explains differences, when to use each grout type, joint width considerations, tile substrates, mixing and sealing tips, and common problems with practical solutions.
| Issue | Sanded Grout | Unsanded Grout |
|---|---|---|
| Best Joint Width | 1/8″ Or Wider | Less Than 1/8″ |
| Suitable Tile Types | Durable Ceramic, Porcelain | Delicate Or Polished Tiles |
| Shrinkage & Cracking | Less Shrinkage | Higher Risk In Wider Joints |
| Scratch Risk | Higher For Soft/Glazed Surfaces | Lower For Polished Surfaces |
| Ease Of Application | Requires More Effort To Clean | Easier To Smooth In Narrow Joints |
Why Choosing The Right Grout Matters
Subway tile is defined by clean grout lines and simple geometry; the wrong grout can ruin the visual effect or cause premature failure. Choosing between sanded or unsanded grout for subway tile determines joint stability, appearance, and long-term maintenance.
What Is Sanded Grout?
Sanded grout contains fine silica sand mixed with cement and additives. The sand provides bulk and reduces shrinkage after curing, making it stronger in wider joints. Sanded grout is typically recommended for joints 1/8 inch (3 mm) or wider.
What Is Unsanded Grout?
Unsanded grout lacks sand and has a smoother, creamier texture made from cement and polymers. It is formulated for narrow joints where sand would not properly compact or could scratch delicate tile surfaces. Unsanded grout is best for joints under 1/8 inch.
Joint Width Guidelines For Subway Tile
Joint width is the primary factor when choosing sanded or unsanded grout for subway tile. Common subway tile installations have joints ranging from 1/16″ to 1/8″. If joint width is 1/8″ or wider, sanded grout is generally recommended; for narrower joints, unsanded grout is the safer choice.
Common Joint Widths And Recommendations
- 1/16″ (1.5 mm) — Use unsanded grout to prevent sand from causing voids and scratches.
- 1/8″ (3 mm) — Transitional; both grouts can work but sanded grout offers better stability in high-traffic areas.
- 3/16″ (5 mm) And Wider — Sanded grout is preferred for strength and minimal shrinkage.
Tile Material And Surface Considerations
Tile composition and finish influence grout choice. Polished, glazed, or soft natural stone tiles are prone to scratching from sand particles. For polished subway tile or natural stone, unsanded grout reduces the risk of surface scratches.
Porcelain And Ceramic Subway Tile
Porcelain and most ceramic tiles are hard and durable, tolerating sanded grout without damage. Sanded grout often provides a more durable joint for these tiles when the joint width allows.
Glass, Marble, And Polished Tiles
Glass subway tile and polished stone share vulnerability to abrasion; using sanded grout can cause micro-scratches and dull the finish. Unsanded grout preserves the tile surface and yields a cleaner look.
Color Consistency And Appearance
Grout color impacts the visual effect of subway tile installations. Sanded grout can appear slightly more textured and matte due to sand particles, while unsanded grout delivers a smoother finish and crisper lines. For a sleek, modern aesthetic with thin joints, unsanded grout often produces the cleanest result.
Performance: Strength, Shrinkage, And Durability
Sanded grout is stronger in compression and less prone to shrinkage because sand stabilizes the matrix. This makes it preferable in floors or heavy-use walls where joints must remain intact. Unsanded grout can shrink more on wider joints, leading to gaps and cracking if used beyond recommended widths.
Application Tips For Best Results
Proper technique matters as much as grout selection. Whether using sanded or unsanded grout, mixing, application, and tooling steps ensure long-lasting joints. Follow manufacturer mixing ratios and apply in small sections to prevent premature skinning.
Mixing And Consistency
Mix grout to a peanut butter consistency for sanded or a slightly creamier paste for unsanded. Avoid overwatering, which reduces strength and increases shrinkage. Let the grout slake (rest) for the recommended time, then remix without adding extra water.
Tooling The Joints
Tool grout with a rubber float and use diagonal strokes to press grout fully into joints. For narrow seams, use a firm but small float or grout finishing tool. Smooth joints to compact grout, reduce voids, and create a consistent profile.
Sealing And Maintenance
Grout is porous and benefits from sealing, especially in showers, backsplashes near stoves, or floors. Both sanded and unsanded grouts should be sealed with a penetrating grout sealer appropriate to the grout chemistry. Sealing reduces staining, moisture intrusion, and the need for aggressive cleaning that can erode grout over time.
Cleaning Practices
Use pH-neutral cleaners for routine maintenance. Avoid acidic cleaners on cement-based grout which can etch and degrade the surface. For stubborn stains, a grout-safe cleaner or mild bleach solution applied briefly and rinsed thoroughly is recommended.
Special Considerations For Showers And Wet Areas
Wet environments exert stress on grout joints due to frequent moisture cycles. Use a quality grout additive or polymer-modified grout to improve flexibility and water resistance. Unsanded grout often seals better in narrow joints, but a polymer-modified sanded grout is preferable for wider joints in shower floors where traction and durability matter.
Repairing And Regrouting Subway Tile
When grout fails, remove the damaged grout to a consistent depth and regrout using the correct type. Mismatching joint width and grout type can lead to repeat failures. Always clean joints of debris before regrouting and consider applying a bonding agent for improved adhesion.
Cost And Availability
Price differences between sanded and unsanded grout are generally small. Sanded grout may be slightly cheaper per bag due to sand content, but cost varies by brand and color. Specialty polymer-modified or stain-resistant formulas cost more but provide better performance in demanding applications.
Common Problems And Troubleshooting
Typical issues include cracking, color inconsistency, efflorescence, and staining. Cracking often stems from using unsanded grout in wide joints or inadequate substrate movement accommodation. Prevent problems by matching grout type to joint width, using movement joints, and following proper installation procedures.
Efflorescence
White powdery deposits result from salts migrating to the surface during curing. Efflorescence is common on new installations and usually diminishes. Clean gently with appropriate cleaners and ensure proper drying and sealing to reduce recurrence.
Color Variation
Shade variations occur due to inconsistent water content, mixing, or different batches. Use grout from the same production batch for a single project and maintain consistent mixing. Test a small area before full application to confirm color and texture.
Practical Scenarios And Recommendations
For a typical subway tile kitchen backsplash with 1/16″ joints and polished ceramic tiles, choose unsanded grout to preserve tile surface and produce tight lines. For a subway tile floor with 1/8″ or wider joints, sanded grout provides better durability and resistance to wear.
- High-Traffic Floors: Sanded grout (1/8″+ joints).
- Bathroom Walls/Backsplashes With Narrow Joints: Unsanded grout.
- Shower Floors: Polymer-modified sanded grout for traction and resilience.
- Glass Or Polished Stone Tile: Unsanded grout to prevent scratching.
Environmental And Health Considerations
Both grouts contain cement; dust control during mixing is important. Use a mask and eye protection when mixing dry grout. Choose low-VOC, low-dust formulations when available to reduce indoor air quality impacts. Follow all safety guidelines on product labels and provide ventilation during application and curing.
Frequently Asked Questions
Can Unsanded Grout Be Used For All Subway Tile Installations?
Unsanded grout should not be used for joints wider than 1/8 inch due to higher shrinkage and lower compressive strength. For wider joints, sanded grout or a blended product is advisable.
Will Sanded Grout Scratch Subway Tile?
Sanded grout can scratch soft, polished tiles if improperly applied or cleaned aggressively. Use unsanded grout for delicate surfaces or protect the tile face during application and clean carefully.
Is Grout Sealing Necessary?
Sealing extends the life of grout and reduces staining, especially in kitchens and showers. Apply a penetrating sealer once grout has fully cured, following the manufacturer’s recommended cure time.
Summary Of Best Practices
Match joint width to grout type, consider tile hardness and finish, use polymer-modified products in wet or high-traffic areas, seal grout after curing, and follow correct mixing and tooling techniques to ensure a durable and attractive subway tile installation.
Resources And Further Reading
Consult tile manufacturer installation guides, the Tile Council Of North America (TCNA) Handbook, and product technical data sheets for specific recommendations. Following industry standards and manufacturer instructions reduces the risk of failure and ensures a professional result.