ANSI A137.1 is the American National Standard Specifications for Ceramic Tile. It defines the types of tile sold in the US, including porcelain, and sets the minimum properties each type must meet. The Tile Council of North America (TCNA) acts as its secretariat.
It is a voluntary consensus standard, not a government licence. But US architects, contractors and many retailers write it into their specifications, so in practice an importer selling into projects is often expected to meet it.
What the standard covers
ANSI A137.1 classifies tile by type and sets requirements for each. The points that matter most for an importer are these:
- It defines porcelain tile as tile with water absorption of 0.5% or less, the same line as group BIa in ISO 13006.
- It sets minimum breaking strength values by use, with 250 lbf the common minimum for floor tiles.
- It sets tolerances for size, thickness, warpage and wedging, which affect how the tile lays.
- It covers properties such as abrasion, frost and chemical resistance where they apply.
- It sets grading and marking rules for standard grade and second grade tile.
Test methods
Test methods are mostly ASTM methods, for example ASTM C373 for water absorption and ASTM C648 for breaking strength. A test report to ISO 10545 measures similar things, but the methods and units differ. If your customer asks for ANSI A137.1 compliance, ask for a report to the ASTM methods it names.
Slip resistance and related standards
Dynamic coefficient of friction, or DCOF, is now covered by a separate standard, ANSI A326.3. It sets a value of 0.42 or more for level interior floors expected to be walked on when wet. The full picture is in our article on floor tile slip resistance.
Large thin porcelain panels and slabs are covered by ANSI A137.3, which applies to gauged porcelain tiles and panels. If you import slabs for the US, check which of the two your customer expects.
Porcelain claims in the US
Because "porcelain" carries a price premium, the US industry runs a certification programme for it through the Porcelain Tile Certification Agency, administered by TCNA. It checks that tile sold as porcelain meets the 0.5% absorption line. Not every project requires it, but some buyers ask for it.
At minimum, make sure every tile you describe as porcelain has a current test report showing absorption of 0.5% or less. Indian "vitrified" tiles are usually in this group, but confirm it for each product.
How it compares with ISO 13006
ANSI A137.1 and ISO 13006 cover the same ground but are not identical. Thresholds, units and grading rules differ, so a tile that meets one is not automatically certified to the other. Our article on ISO 13006 and EN 14411 explains the international system.
Standards are one part of selling into the US. Duties are the other, and they have changed several times since 2025. Read import duties on Indian tiles and confirm the current position with your customs broker.
Next step
We confirm which standard your customers specify, arrange tests to the right methods and check results before loading. To plan a US order, book a free sourcing review.