Ceramic, porcelain, and natural stone tile each bring a different combination of hardness, water resistance, and maintenance to a floor. The right pick depends on the room, the foot traffic, the moisture it will see, and the finish that suits the rest of the space.
Ceramic and porcelain are manufactured tiles shaped from clay and fired in a kiln. Both are classified under ANSI A137.1, the American National Standard for ceramic tile published through the Tile Council of North America. Natural stone, by contrast, is cut from quarried rock and graded under separate ASTM material specifications such as ASTM C615 for granite and ASTM C503 for marble (Natural Stone Tile construction standard).
Before picking a color or finish, compare the families by the same five numbers: water absorption, surface wear rating, slip resistance rating, hardness on the Mohs scale, and installed cost per square foot.
Ceramic, Porcelain, And Natural Stone Tile At A Glance
| Material Family | Governing Standard | Typical Water Absorption | Typical Mohs Hardness | Best Fit |
|---|---|---|---|---|
| Glazed Ceramic | ANSI A137.1 | 0.5% to 7% | 5 to 7 (glaze) | Walls, light traffic floors, dry interiors |
| Porcelain | ANSI A137.1, ASTM C373 | 0.5% or less | 7 to 8 | Floors, showers, exteriors, high traffic |
| Granite | ASTM C615 | 0.1% to 0.5% | 6 to 7 | Kitchens, entries, high traffic floors |
| Marble | ASTM C503 | 0.2% to 0.6% | 3 to 4 | Bathrooms, formal areas, walls |
| Travertine | ASTM C1527 | 0.5% to 2.5% | 3 to 4 | Filled interior floors, baths |
How Tile Is Made And Classified
Ceramic and porcelain are made by pressing a clay mixture into shape and firing it in a kiln. Porcelain uses a denser, finer clay body and is fired at a higher temperature than standard ceramic, which lowers the porosity of the finished piece. The Porcelain Tile Certification Agency certifies products that meet the porcelain water-absorption threshold.
Glazed Vs. Unglazed Ceramic
Glazed ceramic carries a liquid glass or enamel coating applied before a second kiln firing. The glaze provides color, pattern, and a moisture barrier. Unglazed ceramic relies on the clay body itself, which is more slip-resistant but also more porous, so it usually needs sealing in wet areas (Thumbtack tile cost guide).
Through-Body And Color-Body Porcelain
Through-body porcelain has the same color and composition all the way through, so chips and surface wear are less visible. Color-body porcelain carries the surface color through the body but may differ slightly in texture below the glaze layer. Both fall under the same ANSI A137.1 porcelain classification when absorption meets the 0.5% threshold.
Quarry Tile And Saltillo
Quarry tile is an unglazed ceramic with a naturally slip-resistant surface, frequently used in commercial kitchens and mud rooms. Saltillo is a handmade Mexican terra-cotta, sun-dried rather than kiln-fired, and it varies considerably in size, which raises installation time. Both are ceramic products classified under ANSI A137.1 and measured for absorption under ASTM C373.
PEI Wear Ratings And Surface Durability
Glazed ceramic and porcelain tiles carry a PEI wear rating from the Porcelain Enamel Institute. The rating is established under ASTM C1027, the standard test method for determining visible surface abrasion. Higher numbers indicate greater resistance to surface wear from foot traffic.
| PEI Rating | Recommended Use |
|---|---|
| PEI 0 | Walls only; not rated for foot traffic |
| PEI 1 | Very light traffic; residential baths and bedrooms |
| PEI 2 | Light traffic; rooms with soft-soled footwear |
| PEI 3 | Moderate traffic; residential kitchens, living areas |
| PEI 4 | Moderate to heavy traffic; residential entries, light commercial |
| PEI 5 | Heavy traffic; commercial floors, public spaces |
Unglazed porcelain and through-body porcelain rely on color extending through the tile body, so surface wear is visually less noticeable than on a glazed surface. For natural stone, abrasion resistance is reported as a hardness value measured under ASTM C241 (abrasive hardness, Ha) or ASTM C1353 (rotary platform). The Natural Stone Institute sets the minimum at an Ha of 10 for most residential floors and an Ha of 12 for commercial floors exposed to heavy traffic (NSI Travertine Design Manual).
Water Absorption: ASTM C373 And The Porcelain Threshold
Water absorption is the single most cited number in a tile specification. It is measured by ASTM C373, which boils a tile sample, weighs it saturated, then weighs it dry to determine how much water it absorbed.
ANSI A137.1 Water Absorption Classes
ANSI A137.1 groups ceramic and porcelain tile by absorption into four classes:
- Impervious: absorption of 0.5% or less. Porcelain qualifies here.
- Vitreous: absorption of 0.5% to 3%.
- Semi-vitreous: absorption of 3% to 7%.
- Non-vitreous: absorption above 7%; wall use only.
Natural stone absorption is measured under ASTM C97. Granite generally falls between 0.1% and 0.5%, marble between 0.2% and 0.6%, and travertine between 0.5% and 2.5%, although specific lots can sit above or below those ranges (Marble vs Granite properties). Lower absorption generally means better freeze-thaw performance outdoors and better stain resistance indoors when properly sealed.
DCOF Slip Resistance And Safety Standards
Slip resistance for hard-surface flooring is reported as Dynamic Coefficient of Friction (DCOF) under ANSI A326.3. The Tile Council of North America publishes the standard, which uses the BOT 3000E test device with an SBR testfoot and a 0.05% SLS water solution.
The standard’s threshold for level interior spaces expected to be wet is a measured wet DCOF of 0.42 or greater. Below that value, a product is considered suitable only where the surface will be kept dry when walked upon (TCNA DCOF FAQ). Polished porcelain and polished marble often test below 0.42 wet, so they are typically specified only for dry, level interiors unless a textured finish has been applied.
For showers, pool decks, and other wet-plus applications, ANSI A326.3 leaves the value as a manufacturer declaration rather than a fixed numeric threshold, because slip resistance depends on surface structure, drainage, and contamination as well as DCOF. TCNA classifies products into five use categories: Interior Dry, Interior Wet, Interior Wet Plus, Exterior Wet, and Oils/Greases.
Stone Tile: Mohs Hardness And Abrasion Standards
The Mohs scale of hardness ranks minerals from 1 (talc) to 10 (diamond) by what scratches what (Stone Federation GBPN counter guide). For tile selection, the practical Mohs values are:
- Granite: Mohs 6 to 7. Holds polish, resists scratching from typical household use.
- Quartzite: Mohs 7. One of the hardest dimension stones used as flooring.
- Slate: Mohs 4 to 5. Dense, layered; cleft or honed finish.
- Marble: Mohs 3 to 4. Scratches from metal utensils and even from grit underfoot.
- Travertine and Limestone: Mohs 3 to 4. Calcium-carbonate stones that etch from mild acids.
Mohs hardness is a useful screening tool, but the spec to rely on is the ASTM material property table for the specific lot. For granite, ASTM C615 sets minimums for absorption, density, compressive strength, and modulus of rupture. For marble, ASTM C503 sets the equivalent values. Specific lots can fall below those ranges, so requesting the lot data sheet is standard practice before fabrication.
Stone Finishes Available
Stone tile is sold in polished, honed, brushed, tumbled, and cleft finishes. Polished surfaces look the most reflective but show scratches and etch marks quickly under foot traffic. Honed and textured finishes hide wear better and improve wet slip resistance, so they are usually specified for floors even in formal interiors (InspectAPedia floor stone guide).
Sizes, Thickness, And Edge Profiles
Tile is sold in formats from 1-inch mosaics up to large-format slabs. Common residential sizes are 12 by 12 inches, 12 by 24 inches, and 18 by 18 inches, while large-format porcelain panels run from 24 by 24 inches up to gauged porcelain panels several feet per side.
Large-Format And Gauged Porcelain Panels
Any tile with one side longer than 15 inches is generally considered large-format and calls for tighter substrate flatness and a non-sag mortar conforming to ANSI A118.4 or A118.15. Gauged porcelain panels are thin slabs typically 6 mm or thinner, and they require specialized handling and tooling from the installer.
Standard thicknesses for ceramic and porcelain floor tile are roughly 3/8 inch (about 9 to 10 mm). Natural stone floor tile for residential use is commonly 3/8 inch to 1/2 inch, with commercial floors recommending a minimum 3/4 inch thickness for heavy-traffic stone. Edge profiles range from pressed straight edges that rely on a grout joint, to rectified edges that allow minimal 1/16 inch grout lines, to beveled edges that help mask small lippage.
Thinset Mortar Types And Subfloor Requirements
Tile is bonded to the subfloor with thinset mortar. The category is governed by the ANSI A108, A118, and A136 series of standards published through TCNA (TCNA ANSI standards page):
- ANSI A118.1: Dry-Set Portland Cement Mortar (unmodified, mixed with water only).
- ANSI A118.4: Modified Dry-Set Cement Mortar (polymer-modified for better bond strength and flexibility).
- ANSI A118.11: Latex-Portland Cement Mortar over exterior glue plywood.
- ANSI A118.15: Improved Modified Dry-Set Cement Mortar with higher bond strength, suitable for harsh conditions and large-format tile.
Modified Vs. Unmodified Thinset
The main difference between A118.4 and A118.15 is the higher bond strength required by A118.15 (Schluter mortar standards explanation). For most porcelain floor installations, including large-format and heavy tile, a polymer-modified mortar meeting A118.4 or A118.15 is the practical starting point.
Cement Backer Board And Uncoupling Membranes
Wood subfloors typically need an additional layer of cement backer board or an uncoupling membrane to provide a stable, dimensionally consistent surface. Concrete slabs must be cured, dry, and free of cracks wider than the movement-joint guidance in the TCNA Handbook EJ171. Concrete moisture can be tested with in-situ probes under ASTM F2170 before tile is laid.
Subfloor Flatness And Deflection
For most tile installations, the substrate must meet a 1/4 inch tolerance over 10 feet. Where deflection is a concern, such as second-story floors over longer joist spans, the TCNA Handbook points to a deflection limit of L/360 under live load. Addressing flatness and deflection before tile arrives is usually far cheaper than redoing the floor.
Grout Types, Joint Widths, And ANSI Specifications
Grout selection depends on joint width and exposure. The Tile Council of North America summarizes the joint-width guidance as follows (TCNA grout FAQ):
- Joints narrower than 1/8 inch are generally grouted with unsanded grout.
- Joints 1/8 inch and wider are generally grouted with sanded grout.
- Joints wider than 3/8 inch often need a coarser sanded or “wide joint” mix.
Cement-based grouts are governed by ANSI A118.6 (standard cement grout) and ANSI A118.7 (high-performance cement grout with polymers). Epoxy grout, which delivers the highest chemical and stain resistance, is governed by ANSI A118.3 (Custom Building Products grout guide).
Sanded Vs. Unsanded Grout
Polished stone floors should never be grouted with sanded grout, since the sand can scratch the surface. Unsanded grout is the typical choice for marble and similar finishes. For showers and other wet locations, epoxy grout is often preferred for its low absorption.
Movement Joints And Perimeter Gaps
In addition to grout joints between tiles, TCNA Handbook EJ171 calls for expansion and movement joints at the perimeter of tile fields, at changes of plane, and where tile meets a dissimilar material. Skipping these joints is a common source of cracked tile and debonded assemblies.
How Much Does Tile Flooring Cost To Install?
Installed cost varies by material, room size, subfloor condition, and region. The figures below are 2025 ranges drawn from HomeAdvisor, Thumbtack, and Flooring Clarity, in U.S. dollars per square foot installed.
| Material | Material Only ($/sq ft) | Installed ($/sq ft) | Notes |
|---|---|---|---|
| Glazed Ceramic | $1 to $15 | $5 to $15 | Most affordable option; suitable for walls and moderate-traffic floors |
| Porcelain | $2 to $15 | $7 to $20 | Denser, harder to cut; often needs polymer-modified thinset |
| Travertine And Limestone | $5 to $15 | $12 to $30 | Higher labor; sealing adds to maintenance |
| Marble | $10 to $20 | $15 to $40 | Higher material and labor costs |
| Granite | $10 to $40 | Higher than porcelain | Heavy tile; specialty labor common |
Removal of an existing floor adds roughly $2 to $7 per square foot (HomeAdvisor 2025). Subfloor leveling, waterproofing membranes, and complex layouts (herringbone, diagonal, or pattern work) can add 15% to 25% to labor costs. Most installers quote either by the square foot or by an hourly rate between $60 and $120, with regional variation.
Calculating Tile Quantities
Measure the area as length times width in feet, convert to square feet, then add a waste factor of 7% to 15% for straight layouts and up to 20% for diagonal or herringbone patterns. Order from the same lot number to keep shade variation consistent across the field.
Choosing The Right Tile For Each Room
Match the tile’s rated performance to the room’s exposure and traffic rather than selecting on appearance alone.
- Kitchens: Porcelain with a textured finish, PEI 3 or higher, wet DCOF of 0.42 or greater. Through-body or unglazed porcelain helps hide chips at edges and thresholds.
- Bathroom floors: Porcelain or natural stone with adequate slip resistance. Matte or textured finishes are safer when wet. Shower walls and floors should specify porcelain or properly sealed stone rated for constant moisture.
- Entries and mudrooms: Porcelain or granite with PEI 4 or 5 and a textured finish to handle grit and tracked water.
- Living areas: PEI 3 or 4 porcelain is typical; stone is a reasonable option where budget allows and sealing fits the maintenance plan.
- Exterior and patios: Porcelain rated for exterior use, with a structured surface for slip resistance and a frost-resistant rating per ANSI A137.1.
Always request the lot-specific data sheet for natural stone and the manufacturer’s product use classification letter for porcelain. Use those documents, not store displays, as the basis for selecting tile for a specific room.
Tile Flooring FAQs
Below are answers to the most common questions homeowners ask when comparing ceramic, porcelain, and natural stone tile.
Is Porcelain Tile Better Than Ceramic For Bathrooms?
Porcelain meets the impervious threshold of 0.5% water absorption or less under ASTM C373, which makes it the more reliable choice for shower walls, shower floors, and other constantly wet areas. Standard ceramic tile is fine on a dry bathroom floor, but in a shower, the lower absorption of porcelain reduces the risk of water penetration behind the tile.
Can Natural Stone Tile Be Used In Showers?
Yes, with caveats. Granite and quartzite are dense enough for shower use when sealed and maintained. Marble, travertine, and limestone are softer and more porous, and they react with acidic soaps and shampoos, so they are usually reserved for shower walls rather than shower floors. Sealing and ventilation are essential regardless of stone choice.
Which Tile Is Most Scratch-Resistant?
Through-body porcelain and quartzite are the most scratch-resistant tile options for residential flooring. Quartzite rates around 7 on the Mohs scale and porcelain sits at 7 to 8. Marble (Mohs 3 to 4) and travertine (Mohs 3 to 4) will scratch from typical household use, especially on polished surfaces.
Do I Need To Seal Porcelain And Ceramic Tile?
Glazed ceramic and glazed porcelain do not require sealing; the glaze provides the water and stain barrier. Unglazed porcelain, through-body porcelain, and grout lines do benefit from a penetrating sealer in stain-prone areas such as kitchens. Natural stone tile always benefits from sealing before and after grouting, with resealing every 1 to 3 years depending on the stone and product.
What Grout Joint Width Should I Use?
As a starting point, TCNA recommends unsanded grout for joints under 1/8 inch and sanded grout for joints 1/8 inch and wider, with coarser mixes for joints beyond 3/8 inch. The actual width should also reflect the tile’s edge calibration, the substrate flatness, and the look you want. Rectified porcelain can be installed with very tight 1/16 inch joints, while rustic or hand-molded tile usually calls for a wider joint to absorb variation.
