Grout Standards Explained: ANSI A118 and ISO 13007-3 Classes Decoded

Grout standards tell you which category a product belongs to and the minimum performance it was tested to. In North America the key codes are ANSI A118.6 (standard cement grout), A118.7 (high-performance cement grout) and A118.3 (epoxy). Internationally, ISO 13007-3 uses classes such as CG1, CG2WA and RG.

Why grout standards matter

Grout bags carry a lot of marketing language: "stain-proof," "never seal," "crack resistant," "pro grade." None of those terms is defined. The standard numbers are. When a product lists ANSI A118.7, the manufacturer is stating that samples of it passed a defined set of laboratory tests with defined limits. That gives you a common floor to compare products, and it gives designers and inspectors something to write into a specification.

Standards are also how disputes get settled. If a floor fails and the specification called for an A118.7 grout installed per ANSI A108.10, the questions become whether the product met A118.7 and whether the installer followed A108.10. Knowing which documents apply is useful even for a homeowner reviewing a contractor's bid.

The ANSI family: A118 materials and A108 installation

The American National Standards for tile are developed through a committee administered by the Tile Council of North America (TCNA) and published together as the ANSI A108/A118/A136 specifications. The structure is simple once you see it: A118 documents describe materials, A108 documents describe installation methods, and A137.1 describes the ceramic tile itself.

ANSI A118.6: standard cement grout

A118.6 is the baseline for cement grouts. Historically it grouped several types (commercial portland cement grouts, sand-portland cement grouts mixed on site, dry-set grouts and latex-portland cement grouts). In practice, any factory-bagged cement grout that does not claim A118.7 is likely an A118.6 product. These grouts are fully serviceable, but they are more sensitive to mixing water and cleanup technique, and they usually benefit from sealing. See sanded grout and unsanded grout for how they are used.

ANSI A118.7: high-performance cement grout

A118.7 is the standard behind grouts sold as high performance, rapid setting or "advanced" cement grouts. It adds requirements that A118.6 grouts are not held to, including limits on shrinkage and water absorption and a check on color consistency. These are polymer-modified products and are mixed with water only. Our dedicated guide to high-performance cement grout covers mixing and use.

ANSI A118.3: epoxy grout

A118.3 covers 100% solids epoxy systems that are chemical resistant yet still cleanable with water before cure. It tests properties such as bond, compressive strength, shrinkage, thermal shock and chemical resistance. A118.3 compliance is the reason you can specify epoxy for commercial kitchens and other harsh settings with confidence. See epoxy grout.

Products without a dedicated ANSI category

Single-component premixed grouts (usually acrylic or urethane dispersions that cure by drying, sometimes with additional chemistry) do not fit neatly into A118.6, A118.7 or A118.3. Manufacturers typically state that the product "meets or exceeds ANSI A118.7" for certain properties, or that it was tested against A118.3 criteria for stain or chemical resistance. That can be meaningful, but read the wording: "exceeds A118.7 for shrinkage" is a narrower claim than "meets A118.7." See premixed grout and urethane grout.

ISO 13007-3: the international classes

ISO 13007-3 is the international standard for tile grouts, and its classification scheme mirrors the European standard EN 13888. Many products sold in North America now carry an ISO class next to the ANSI number, which is useful because the ISO codes are compact and descriptive. The test methods are defined in ISO 13007-4.

The class code is built from a base type and optional suffixes:

• CG: cementitious grout.
• RG: reaction resin grout (epoxy and similar systems).
• 1: normal grout meeting the basic requirements.
• 2: improved grout that also meets at least one additional characteristic.
• W: reduced water absorption.
• A: high abrasion resistance.
• F: fast setting (develops specified early strength quickly).

So CG2WA is an improved cementitious grout with reduced water absorption and high abrasion resistance, and CG2WAF adds fast setting. RG has no suffixes because reaction resin grouts already meet demanding limits by definition.

These are the limits as commonly published for the standard; confirm against the current edition if you are writing a specification. The point for a buyer is the scale of the differences: an RG product loses roughly one eighth the volume of a CG1 product in the abrasion test and absorbs a tiny fraction of the water.

How ANSI and ISO line up

The two systems were developed separately and do not use identical tests, so there is no perfect one-to-one mapping. In practice, though, they line up closely enough to guide a purchase:

What standards do not tell you

A standard number is a pass/fail threshold measured on lab specimens mixed and cured under controlled conditions. It does not cover several things that matter a great deal on a real job:

• Installation tolerance. A product that meets A118.7 when mixed at the exact water ratio may fall well short when overwatered. Standards do not rate forgiveness.
• Color range and fidelity. A118.7 addresses consistency between samples, not whether the cured color matches the color chart. See the grout color guide.
• Specific chemical exposures. Even A118.3 and RG products differ in resistance to particular acids, solvents and cleaners. Industrial specifications list the chemicals by name.
• Movement. No grout standard makes grout a substitute for movement joints. TCNA EJ171 still applies; see caulk vs grout at movement joints.
• Waterproofing. No grout standard claims grout is waterproof. Waterproof membranes are covered by a different standard, ANSI A118.10.

Installation standards that apply to grout

Choosing a compliant material is half the specification. The other half is installation. ANSI A108.10 covers grouting with cement grouts: joint preparation, filling, cleaning and curing. A108.6 covers epoxy. A108.02 sets general requirements that apply across methods, including environmental conditions such as the temperature range for installation and the protection of new work. Manufacturer instructions add product-specific requirements that are typically incorporated by reference.

The TCNA Handbook ties all of this together with installation method details (floor, wall, shower and exterior assemblies) and the EJ171 movement joint guidelines. For homeowners, the useful takeaway is that a contractor who writes "grout per ANSI A108.10 with A118.7 grout, movement joints per TCNA EJ171" into a proposal is committing to a recognized, checkable standard of work.

Using standards to choose a grout

1. Define the exposure. Residential dry area, residential wet area, exterior or freeze-thaw, commercial traffic, or chemical exposure.
2. Set a minimum class. Dry residential: A118.6 is acceptable, A118.7 preferred. Wet residential and floors: A118.7 / CG2WA. Commercial kitchens and chemical exposure: A118.3 / RG at minimum, with chemical resistance checked by name.
3. Check the TDS for the details the standard does not cover. Joint width range, suitability for glass or polished stone, exterior and submerged ratings, and sealing guidance.
4. Write it down. Put the standard numbers and product name in the scope of work so substitutions are visible.

Our grout type selector walks through the same decision interactively, and grout product lines compared shows how common product families map to these categories.