Choosing the wrong grout type leads to cracking, crumbling, and expensive rework. The rule is simple: joint width determines grout type. Here is the complete breakdown so you get it right the first time.
The Rule: Joint Width Under 1/8" = Unsanded
If your grout joints are less than 1/8 inch wide, use unsanded grout. Unsanded grout is a smooth mixture of Portland cement, pigment, and water-retention additives without any aggregate. Its smooth consistency fills narrow joints completely without the sand particles preventing full compaction. Trying to force sanded grout into narrow joints leaves voids and an inconsistent finish.
The Rule: Joint Width 1/8" and Wider = Sanded
If your grout joints are 1/8 inch or wider, use sanded grout. The fine sand aggregate gives the grout structural strength in wider joints. Without sand, unsanded grout shrinks and cracks as it cures in wide joints — sometimes within the first week. For joints over 1/2 inch, use wide-joint sanded grout with coarser aggregate.
Unsanded Grout: Best Uses
- Rectified porcelain tile with tight 1/16" joints
- Polished marble, granite, and natural stone — sand can scratch polished surfaces
- Glass tile — sand scratches the back coating
- Vertical wall tile with tight joints — unsanded is stickier and resists slumping
Sanded Grout: Best Uses
- Floor tile of any kind with standard 1/8" to 3/8" joints
- Subway tile — typically 1/8" to 3/16" joints
- Outdoor tile and pavers — sanded grout handles thermal movement better
- Any joint wider than 1/8" where structural strength matters
Popular Brands Compared
Use our tile grout calculator with brand-specific coverage rates:
- Mapei Keracolor U (Unsanded) — 95 sq ft per 10-lb bag, excellent color consistency
- Mapei Keracolor S (Sanded) — 70 sq ft per 25-lb bag, industry workhorse
- Laticrete Permacolor Select — 72 sq ft per 25-lb bag, stain resistant
- TEC Power Grout — 65 sq ft per 25-lb bag, epoxy-like performance
- Custom Prism — 70 sq ft per 17-lb bag, color-consistent
- Bostik TruColor — 60 sq ft per 9-lb bag, pre-mixed urethane
What About Epoxy Grout?
Epoxy grout works at any joint width and does not need sealing. It is waterproof, stain-proof, and extremely durable. The tradeoff: it costs 3-5x more than cement grout, has a shorter working time (about 30 minutes), and is harder to clean up. Epoxy is worth it for showers, kitchen backsplashes, and commercial floors where staining is a concern.
Quick Decision Matrix
- Joint under 1/8" + any tile = unsanded
- Joint 1/8" or wider + ceramic/porcelain = sanded
- Any joint + polished stone or glass = unsanded (regardless of width)
- Wet areas + any joint + budget allows = epoxy