When you are deciding how to choose tile grout, the answer depends on three variables: joint width, surface environment, and maintenance tolerance. For joints narrower than 1/8 inch, use unsanded grout; for wider joints, use sanded grout; and for wet or chemically exposed surfaces, invest in epoxy grout without hesitation. If you are simultaneously planning a full floor installation, our guide to choosing floor underlayment will help you establish the proper substrate before grout becomes relevant.
There are three primary grout categories in residential and commercial installation: sanded grout, unsanded grout, and epoxy grout. Each is engineered for a specific set of conditions, and selecting the wrong type causes cracking, staining, or complete joint failure within months of installation. This guide gives you a precise, practical framework for matching your project requirements to the correct product, without relying on guesswork or the advice of a store associate who does not know your specific application.
Grout is not a cosmetic afterthought. It occupies between five and fifteen percent of any tiled surface's total area, and it bears direct exposure to foot traffic, moisture, cleaning chemicals, and thermal expansion cycles. Choosing the right product from the start is the single most consequential material decision you will make after selecting the tile itself. For a broader view of home finishing projects, browse our home improvement category guides.
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Grout is a cementitious or resin-based filler material that seals and stabilizes the gaps between individual tiles. It performs four core functions simultaneously: it locks tiles firmly in position against lateral movement, prevents water from infiltrating the substrate (the backing layer beneath the tile surface), accommodates minor thermal expansion between adjacent tiles, and creates the finished visual surface that defines the aesthetic of the entire installation. According to Wikipedia's overview of grout, cement-based grouts have been a fundamental building material for centuries, though modern polymer-modified formulas offer considerably better flexibility and stain resistance than their historical predecessors.
Portland cement grout dominated the tile industry for most of the twentieth century, and it remains the most widely sold product in home improvement stores today. Epoxy grout entered the market as an industrial solution for food processing plants and chemical laboratories, where resistance to aggressive agents was non-negotiable. Its gradual availability in residential formulations has given homeowners access to a product previously exclusive to commercial contractors. This history matters because it explains why cement grout remains the default recommendation despite its maintenance requirements — familiarity and shelf availability drive purchasing decisions more reliably than performance data does, and that default leads many installers toward the wrong product for their specific conditions.
The table below captures the essential specifications at a glance. Use it as your primary reference point, then read the detailed sections for the nuance that a table cannot fully convey.
| Grout Type | Joint Width | Best Surfaces | Requires Sealing | Avg. Cost (per lb) | Durability Rating |
|---|---|---|---|---|---|
| Sanded | 1/8″ to 1/2″ | Floors, ceramic wall tile, stone pavers | Yes | $0.50–$1.50 | Good |
| Unsanded | Up to 1/8″ | Glass mosaic, polished marble, wall tile | Yes | $0.75–$2.00 | Moderate |
| Epoxy | 1/16″ to 1/2″ | Showers, kitchens, commercial floors | No | $2.50–$6.00 | Excellent |
Sanded grout contains fine silica sand mixed into the cement base to prevent excessive shrinkage as the material cures. You must use sanded grout for any joint that measures between 1/8 inch and 1/2 inch wide. The sand acts as a structural filler, giving the cured material enough body to resist cracking under foot traffic and thermal movement. Standard ceramic floor tiles, large-format stone pavers, and most outdoor installations naturally produce joints that fall within this range and therefore require sanded grout as a baseline requirement, not an optional upgrade.
Unsanded grout is a smooth, sand-free cement mixture that flows into narrow joints with minimal effort. Use it exclusively for joints 1/8 inch wide or narrower. Its smooth texture adheres well to vertical surfaces and will not scratch delicate tile faces such as polished marble or glass mosaic during application. Because it lacks the structural filler that sand provides, unsanded grout shrinks more during curing and cracks predictably if you force it into a joint that is wider than its design limit — the failure is structural, not cosmetic.
Epoxy grout is a two-part system — a resin and a chemical hardener — that you mix immediately before application. It cures through a chemical reaction rather than through evaporation, which produces a finish that is virtually impervious to stains, bacteria, and most household chemicals. Epoxy grout is the correct choice for showers, pool surrounds, and any surface exposed to oils or aggressive cleaning agents. It costs significantly more than cement grout, but it requires no sealing and outlasts cement alternatives by a wide margin. If you want to understand the broader chemistry of two-part epoxy systems, our comparison of epoxy vs. wood glue explains how resin-based materials cure and where they perform best.
For shower floors and walls, epoxy grout is the professional recommendation, and the argument for it is straightforward: cement-based grouts in continuously wet conditions require sealing every one to two years, and mold growth in the joints remains a persistent problem regardless of sealing frequency. If cost constrains you to cement grout in a wet area, apply a penetrating sealer (a liquid product that soaks into the grout's pores and repels water) within 72 hours of full curing. Before making your final grout selection, review our guide to choosing bathroom floor tile — tile porosity and surface texture directly determine your joint width, which in turn determines whether you need sanded or unsanded grout.
Kitchen backsplashes almost always use narrow-joint glass or ceramic mosaic tiles, placing unsanded grout as the default material. However, the grease and food acid exposure typical in kitchens makes a strong argument for epoxy grout even in this smaller-scale application. If your budget requires cement grout, choose an unsanded formula with a latex additive (a flexible polymer that improves stain resistance and adhesion to the tile edges) and seal the grout within 48 hours of reaching full cure. Skipping the sealer in a kitchen is the fastest path to permanent grout discoloration.
Outdoor tile installations endure dramatic temperature swings that expand and contract both the tile and the substrate beneath it, placing structural stress at every joint. Sanded grout handles this cyclical movement more effectively than unsanded grout because the sand filler distributes compressive stress across a larger particle matrix. Epoxy grout is not recommended for most outdoor UV-exposed surfaces because extended sunlight causes the resin to yellow and become brittle over time. Choose a sanded cement grout with a polymer additive for patios, pool decks, and exterior entryways, and plan for resealing every two years.
Pro tip: At any outdoor tile installation, leave a 1/4-inch perimeter gap at walls and transitions and fill it with flexible silicone caulk rather than grout — rigid grout at these movement joints cracks within the first seasonal freeze-thaw cycle.
Many homeowners believe that dark-colored grout hides dirt more effectively than lighter alternatives — and that belief is only partially correct. Dark grout does conceal surface grime and foot traffic residue in the short term. However, it also makes efflorescence (the white mineral deposits that leach out of cement as it cures) dramatically more visible against the dark background, and efflorescence is nearly impossible to fully eliminate on cement grout. Light grout in an epoxy formula shows surface dirt more readily but develops far fewer permanent discoloration problems over time. Choose your grout color based on your realistic maintenance capacity and the long-term look you want to maintain, not on the oversimplified assumption that darker always means cleaner.
The most persistent misconception in tile installation is that all grout types require sealing. Epoxy grout is inherently non-porous, meaning liquids rest on its surface rather than absorbing into the material — applying a silicone-based sealer to epoxy grout wastes money and accomplishes nothing measurable. Cement-based grout, both sanded and unsanded, absolutely requires sealing, and skipping this step is the primary cause of premature staining and mold infiltration. If you are researching the broader category of perimeter protection products that accompany any tile installation, our comparison of caulk vs. sealant clarifies which product belongs at movement joints versus which belongs at field joints.
Sanded cement grout is the least expensive option, typically priced between $0.50 and $1.50 per pound at major home improvement retailers. Unsanded cement grout runs slightly higher, from $0.75 to $2.00 per pound, reflecting its more refined particle composition. Epoxy grout commands a significant premium, with most residential formulas priced between $2.50 and $6.00 per pound. A standard 40-square-foot bathroom floor requires approximately 10 to 15 pounds of grout depending on joint width and tile size, so the total material cost difference between sanded cement and epoxy for that scope of work typically ranges from $25 to $70 — a modest gap relative to the total project budget.
Material cost is only one dimension of the true investment you are making. Cement grout requires a penetrating sealer ($15 to $30 per bottle, sufficient for two or three applications) plus the recurring labor of annual or biennial resealing. Epoxy grout eliminates this ongoing cost entirely. Over a ten-year period, a bathroom grouted with epoxy may cost less in total expenditure than the same bathroom grouted with cement and properly maintained on schedule. When you are weighing costs across your full project, consider whether adjacent floor areas use tile, laminate, or vinyl plank — our comparison of laminate vs. vinyl plank flooring helps you align material selections and maintenance protocols across the entire installation from the beginning.
Cracked grout is almost always the result of one of three root causes: the wrong grout type specified for the joint width, inadequate substrate preparation before tile installation, or grout mixed with too much water during application. If you used unsanded grout in a wide joint, the shrinkage cracks are structural in nature, and the only correct repair is full removal and replacement. For hairline surface cracks in properly specified cement grout, clean the joint thoroughly and apply a pre-mixed grout repair product before moisture infiltrates the crack and degrades the substrate beneath the tile. Do not apply grout colorant over cracked joints — this masks the structural failure without addressing it, and the crack will propagate further under continued load.
Unsealed cement grout stains permanently in most cases because the mineral matrix is inherently porous and absorbs pigmented liquids at a molecular level before you can blot them away. For surface stains that have not fully penetrated, a diluted oxygen bleach solution scrubbed with a stiff-bristle brush removes a significant portion of the discoloration without damaging the grout binder. For deeply set stains, grout-specific acidic cleaners are more effective, but you must rinse the joint thoroughly and apply fresh sealer immediately after cleaning. Mold in grout joints is a hygiene concern, not merely a cosmetic one — address it with a diluted bleach solution, improve ventilation in the space, and reseal the grout before returning the surface to regular use.
Warning: Never use vinegar or other acidic cleaners on cement grout — the acid dissolves the calcium carbonate binder that holds the joint together, permanently weakening the structure with each repeated application.
Consider a master bathroom with a curbless walk-in shower using 12-by-24-inch porcelain floor tile and 3-by-12-inch subway wall tile. The floor joints measure 3/16 inch — sanded grout territory by width — but the continuous wet environment makes cement grout a long-term maintenance liability. The correct answer is epoxy grout throughout the entire shower enclosure. For the dry-area floor outside the shower, sanded cement grout with a penetrating sealer is a reasonable and cost-effective choice. On the subway tile walls, where joints measure 1/16 inch, use unsanded epoxy if budget permits, or a premium unsanded cement grout sealed within 48 hours. When coordinating finish materials across the same space, our comparison of polyurethane vs. polycrylic finishes explains how to match sheen levels between cabinetry coatings and the tile's visual weight.
An 18-by-18-inch natural stone travertine floor with 1/4-inch joints presents what looks like a standard sanded grout application — but travertine is soft and porous enough that the silica sand in standard sanded grout abrades the tile surface during the float-and-wipe application process. The correct product is a polymer-modified, non-sanded large-format grout specifically formulated for joints up to 3/8 inch without abrasive sand particles. Apply a stone-specific penetrating sealer to both the tile and the grout immediately after curing. Verify that your substrate is adequately prepared before tile installation begins — our guide to choosing floor underlayment covers the specific thickness and rigidity requirements for stone tile substrates that standard underlayment products do not meet.
Cement-based grout requires its first sealer application within 48 to 72 hours of reaching full cure, which typically occurs 24 to 48 hours after installation depending on ambient temperature and humidity levels in the space. Apply a penetrating sealer using a small foam brush or a dedicated grout sealer applicator bottle, working in three-foot sections and wiping any excess product off the tile face immediately before it dries. Allow the sealer to cure fully per the manufacturer's instructions before exposing the grout to water. Reseal annually in wet areas and every two years in dry interior rooms — set a calendar reminder so the schedule does not slip.
Weekly cleaning with a pH-neutral cleaner (a product formulated to be neither acidic nor alkaline, which preserves both the sealer chemistry and the cement binder) is the single most effective long-term maintenance habit you can establish. Avoid steam cleaners on cement grout — high-pressure steam forces moisture past the sealer layer and accelerates efflorescence and joint degradation. Grout haze (the thin film of grout residue left on tile faces during installation) must be removed with a damp sponge within the first 30 minutes of application; dried haze requires a specialized acid-wash remover that risks etching natural stone surfaces. Consider how your grout care routine integrates with other finish maintenance in the same rooms — our guide to choosing interior paint finishes explains how different sheen levels affect cleaning frequency and product compatibility in adjacent wall and ceiling surfaces.
Sanded grout contains fine silica sand that prevents shrinkage in joints wider than 1/8 inch, making it the standard choice for most floor tile applications. Unsanded grout is a smooth, sand-free formula designed specifically for joints 1/8 inch wide or narrower, where it adheres more effectively and will not scratch delicate tile surfaces during application.
Yes — and for most shower applications, epoxy grout is the superior choice by a significant margin. It resists continuous moisture, mold, staining, and cleaning chemicals without requiring any sealing, making it the lowest-maintenance grout option available for wet environments.
Cement-based grout — both sanded and unsanded — requires sealing to prevent staining and moisture infiltration into the substrate. Epoxy grout does not require sealing because its cured resin surface is non-porous and repels liquids without any additional treatment.
Measure your tile joints before purchasing anything. For joints between 1/8 inch and 1/2 inch, use sanded cement grout or epoxy grout. For joints narrower than 1/8 inch, use unsanded grout. If the floor is in a wet area or a high-traffic space, choose epoxy grout regardless of joint width for maximum long-term performance.
Properly sealed cement grout in a low-traffic dry interior area lasts 15 to 25 years before replacement is warranted. In continuously wet environments, expect to regrout every 8 to 15 years. Correctly installed epoxy grout can last the full lifetime of the tile without requiring replacement.
You can apply fresh grout over existing grout if the old grout is structurally sound, completely clean, and free of mold. However, this method is a temporary solution that reduces joint depth and compromises long-term adhesion. The correct repair approach is to remove the old grout with a grout saw and regrout from a clean joint surface.
Post-installation cracking is most commonly caused by using the wrong grout type for the joint width, mixing the grout with excess water to make it easier to spread, or installing tile over a substrate that flexes under load. Address the underlying cause before making repairs, or the new grout will crack in the identical locations within the same time frame.
About Lindsey Carter
Lindsey and Mike C. grew up in the same neighborhood. They also went to the same Cholla Middle School together. The two famillies from time to time got together for BBQ parties...Lindsey's family relocated to California after middle school. They occasiotnally emailed each other to update what's going on in their lives.She received Software Engineering degree from U.C. San Francisco. While looking for work, she was guided by Mike for an engineering position at the company Mike is working for. Upon passing the job interview, Lindsey was so happy as now she could finally be back to where she'd like to grow old with.Lindset occasionally guest posted for Mike, adding other flavors to the site while helping diverse his over-passion for baseball.
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