Tile Adhesive Classification: EN 12004 and ANSI A118

Tile Adhesive Classification: Why Two Systems Exist

Tile adhesive classification exists so that a specifier can state performance with a short code instead of a long paragraph. ISO 13007-1 and the European EN 12004-1 describe an adhesive by type, class and optional characteristics, for example C2TE. In North America the ANSI A118 family, available through the Tile Council of North America (TCNA), gives each material family its own standard and adds a few letters. A Laticrete datasheet notes that ISO standards are used in many countries while the ANSI standards remain the reference standard for North America.

The BSI listing for EN 12004-1:2017 gives its title as requirements, assessment and verification of constancy of performance, classification and marking. Our guide to tile adhesive formulation covers the ingredients behind these classes, and this guide covers the classes themselves.

The European and ISO system is built as a matrix, so reading the code left to right comes first.

EN 12004 and ISO 13007: Types, Classes and the Designation Code

A tile adhesive classification code under EN 12004 or ISO 13007 is built from left to right: the type, the class, then any optional characteristics. ISO 13007-1 defines three types, cementitious (C), dispersion (D) and reaction resin (R). Each type has a normal class (1) and an improved class (2), and optional letters add fast setting, slip resistance, extended open time, deformability or plywood adhesion. Read in order, the code tells a buyer what the product is, how well it bonds and which special behaviours it has.

The ISO 13007-1:2014 sample pages give C2ES1P1 as a worked example. It describes a deformable, improved cementitious adhesive with extended open time and normal adhesion to exterior glue plywood. The class number comes from the strength tests, so those tests come next.

EN 12004 C1 C2 Adhesive: The Four Tensile Adhesion Tests

In tile adhesive classification, the class of a cementitious adhesive comes down to one measurement repeated under four conditions. Tensile adhesion strength is measured initially, after water immersion, after heat ageing and after freeze-thaw cycles. A C1 adhesive must reach at least 0.5 N/mm² in all four, and a C2 adhesive must reach at least 1.0 N/mm² in all four. Both classes also need at least 0.5 N/mm² when tiles are placed after not less than 20 minutes of open time.

ISO 13007-1 states that the cementitious adhesive must comply with all the C1 fundamental characteristics, and the C2 additional characteristics raise the strength levels. A manufacturer's summary of DIN EN 12004 presents the same four conditions and the same two strength levels. Our guide to cement versus polymer-modified tile adhesives shows how those levels map to product types.

The optional letters then describe how the adhesive behaves on the wall, not only how strong it is.

Optional Characteristics: F, T, E and S1/S2 Explained

The optional letters in a tile adhesive classification describe what an adhesive does between mixing and curing, and what it can survive afterwards. T limits how far a tile slips on a vertical surface, E lengthens the time during which tiles can still be placed, and F speeds early strength. S1 and S2 describe how far a hardened adhesive can deform. Each letter has its own test, so a designation such as C2TE tells the buyer that two extra tests were passed.

The T, E, S1 and S2 values come from a Laticrete ISO 13007 datasheet, and the manufacturer summary of DIN EN 12004 agrees with them. Only that summary gives the F values, so check them against the standard before quoting them. The plywood thickness comes from the ISO 13007-1 text.

• Open time — ISO 13007-1 defines it as the maximum interval after application at which tiles can be embedded and still meet the specified tensile adhesion strength.
• Slip — the downward movement of a tile applied to a combed adhesive layer on a vertical surface.
• Adjustability — the maximum interval after which the tile position can be adjusted without significant loss of adhesion strength.
• Transverse deformation — the deflection recorded at the centre when a beam of hardened adhesive is loaded at three points.

Cementitious adhesives carry the full set of letters, while dispersion and reaction resin adhesives are classified on a shorter list.

Dispersion and Reaction Resin Adhesives: D and R Classes

Dispersion and reaction resin adhesives follow the same tile adhesive classification structure but are tested differently from cementitious adhesives. EN 12004-2:2017 specifies tensile adhesion strength for cementitious adhesives, and shear adhesion strength for dispersion and reaction resin adhesives. Dispersion adhesives are ready-for-use aqueous polymer dispersions with fillers, and reaction resin adhesives cure by chemical reaction. Both have normal and improved classes, and the S letter is limited to cementitious adhesives.

Because shear and tensile tests load the bond differently, strength values for D and R adhesives are not comparable with the C values. The manufacturer summary of DIN EN 12004 lists shear levels for D and R classes, but it states two different values for D1, so this guide leaves those figures out. Read the current EN 12004-1 text before setting a D or R target.

That covers the European and ISO structure, and the North American family follows a different logic.

ANSI A118 Tile Adhesive Standards: A118.1, A118.4 and A118.15

The ANSI A118 series is a set of material specifications available through the Tile Council of North America, and each standard covers one family of setting materials. TCNA's list of ANSI standards includes A118.1 for dry-set cement mortar, A118.4 for modified dry-set cement mortar and A118.15 for improved modified dry-set cement mortar, all in 2023 editions. Related standards cover EGP (exterior glue plywood) modified dry-set mortar, epoxy and organic adhesives. Together they form the vocabulary of North American tile adhesive classification that a specifier writes on a drawing.

Two 2013 manufacturer bulletins, from Laticrete and Custom Building Products, describe the revision that created the current structure. The titles of A118.1 and A118.4 dropped composition words so that the standards focus on physical properties, and the suffixes E, F and T were added. A118.15 was created for mortars with higher shear bond strength.

• E — extended working time.
• F — fast setting. Custom's bulletin describes A118.1F as reaching a shear bond strength of 50 psi or more in 4 hours.
• T — non-sag performance on vertical applications.
• A118.15 targets — the Laticrete bulletin names large format tiles, glass tile, submerged applications and exterior veneers.
• 28-day impervious tile shear — both bulletins give 200 psi for A118.4 and 400 psi for A118.15 at the time of the 2013 revision.

With both structures laid out, the practical question is how they differ when a product is sold in both markets.

EN 12004 vs ANSI A118: Tensile Adhesion vs Shear Bond Strength

The fundamental difference between the two tile adhesive classification systems is what they pull on. EN 12004 and ISO 13007 report tensile adhesion strength for cementitious adhesives in N/mm², while the ANSI bulletins describe shear bond strength in psi. The two cannot be compared by converting units, even though 1 N/mm² is about 145 psi. A single product can carry both classifications, and a Mapei datasheet lists C2ES1P1 under ISO 13007 for one polymer-modified mortar alongside A118.4E, A118.11 and A118.15E.

The Laticrete bulletin records that the 2013 A118.4 revision added the ISO 13007 open time requirement. That requirement is at least 0.5 MPa at 20 minutes for normal mortar and at 30 minutes for extended open time, with an optional slip limit under 0.5 mm. Mapei's document states that an ANSI A118 specification defines a minimal acceptable level of performance, while ISO 13007 classifications define individual characteristics. Strength is where the systems stay apart, and that is what a test programme has to respect.

Tile Adhesive Standards Testing: Building a Test Programme

A tile adhesive standards testing programme maps every letter in the target code to one named test. EN 12004-2:2017 specifies six methods: open time, slip, tensile adhesion of cementitious adhesives, shear adhesion of dispersion adhesives, shear adhesion of reaction resin adhesives, and transverse deformation of cementitious adhesives. Its scope is adhesives for internal and external installation of ceramic tiles. ISO 13007-2 plays the same role in the ISO system.

1. Fix the target code — for example C2TE, and list every test it requires.
2. Initial tensile adhesion — at least 1.0 N/mm² for C2.
3. After water immersion — at least 1.0 N/mm² for C2.
4. After heat ageing — at least 1.0 N/mm² for C2.
5. After freeze-thaw cycles — at least 1.0 N/mm² for C2.
6. Open time — at least 0.5 N/mm² after not less than 20 minutes, and after not less than 30 minutes for E.
7. Slip — no more than 0.5 mm for T.
8. Transverse deformation — at least 2.5 mm for S1 and at least 5 mm for S2.

Knowing the tests shows what each class demands of the formulation.

What Each Class Demands of the Formulation

Each letter in a tile adhesive classification code is a performance target that the formulation has to deliver at production scale. ISO 13007-1 defines a cementitious adhesive as hydraulic binding agents, aggregates and organic additives, and a Laticrete datasheet names latex polymers and moisture-retention additives as examples of those organic additives. The requirements, not the recipe, define the class, so two different formulations can reach the same code. The table translates each target into the property to protect.

Our guides to rheology control with cellulose ethers and to dry mix mortar raw materials and blending cover the levers behind these properties. Scale-up has to repeat the test suite on plant batches, because mixing and blend uniformity at production scale can differ from the laboratory. Our construction chemical regulatory compliance guide covers the CE marking side of the European route.

Specialist support shortens the path from a target code to a validated product.

Working With a Construction Chemicals Formulation Consultant

Tile adhesive classification work sits between formulation chemistry and test laboratory practice, and a wrong assumption early costs a full test cycle. A construction chemicals formulation consultant sets the target code for each market and builds the test plan around it. Construction chemical product development services also cover specification writing and pilot batches. A contract formulation scale-up partner then moves the product into a plant that can reproduce the laboratory results.

1. Choose the markets — EN and ISO, ANSI, or both.
2. Set the target code — for example C2TE for Europe and A118.15E for North America.
3. Formulate with margin — aim above each threshold so that batch variation does not drop the class.
4. Run the full test suite — all four tensile conditions plus the open time, slip and deformation tests the code needs.
5. Repeat on plant batches — confirm that production mixing reproduces the laboratory values.
6. Prepare the documents — build the technical file for the certification route in each market.
7. Monitor batches — retest on a schedule so that the class stays valid over time.

Our construction chemicals range shows where tile adhesives sit among the other products, and our guide on hiring a construction chemicals formulation consultant explains how to judge candidates. Entrepreneurs planning a plant will find our tile adhesive manufacturing business guide useful. Global Formulation provides tile adhesive formulation, classification test planning and scale-up for construction chemical manufacturers.