oSIST prEN 13408:2026

oSIST prEN 13408:2026 is the Slovenian publication of the CEN draft European Standard prEN 13408:2026 from CEN/TC 193. It specifies a laboratory test method for determining bond strength between a cementitious or calciumsulfate-based floor levelling compound underlayment and a standard substrate. Manufacturers, test laboratories, and quality teams use it to compare products under defined mixing, conditioning, loading, and reporting conditions.

What does oSIST prEN 13408:2026 specify?

oSIST prEN 13408:2026 specifies one test method for measuring the bond between a set floor levelling compound and a standard concrete test slab. The purpose is to judge how well a levelling compound forms a bonded layer on a load-bearing substrate before floor coverings are installed.

The standard is organized into nine clauses:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Principle
• Clause 5 - Standard test conditions
• Clause 6 - Apparatus and material
• Clause 7 - Procedure
• Clause 8 - Evaluation and expression of results
• Clause 9 - Test report

What are the key requirements of oSIST prEN 13408:2026?

Test conditions and setup

oSIST prEN 13408:2026 requires standard test conditions of 23 ± 2 °C and 50 ± 5 % relative humidity, with air circulation below 0.2 m/s. All test materials and apparatus are stored under these conditions during the test. In practice, this keeps the bond test comparable from one laboratory to another.

Clause 6 specifies the main equipment and materials: a tensile testing machine, a concrete slab, flexible moulding sheets, a fast-setting reactive resin adhesive, rigid metal plates, the prepared floor levelling compound mixture, and primer if the manufacturer specifies it. This tells the user what must be on hand before testing starts.

Specimen preparation

Clause 7 requires preconditioning the concrete slabs and moulding sheets for at least 24 h under the standard test conditions. Eight test areas are required for each floor levelling compound. If a primer is specified, the concrete slab is primed as recommended by the manufacturer.

The moulding sheet is placed on the slab, the cavities are filled immediately after mixing, and surplus material is removed to leave a filled, even surface. The moulding sheet is removed within three days, and in the 24 h before testing a metal plate is bonded to each area. In practice, this sequence controls how the bond specimen is formed and when it is ready for pull-off testing.

Test execution and timing

Clause 7 requires testing 14 d after mixing the floor levelling compound. The specimen is pulled with a tensile testing machine at a force increasing rate of 250 ± 50 N/s, applied perpendicularly and centrally. The test records the breaking load and the mode of failure.

The failure mode is reported in accordance with EN ISO 10365 as cohesive failure in the floor levelling compound, cohesive failure in the substrate, or adhesive failure. This matters because the failure type helps users understand whether the bond, the compound, or the substrate is the weak point.

Evaluation and reporting

Clause 8 gives the calculation basis for bond strength in MPa and uses the bonded area of 2 500 mm². The standard requires the arithmetic mean of eight results, with outlier handling when a result differs by more than 20 % from the mean. If fewer than four results remain, the whole test is repeated. That makes the reported value more stable and less dependent on a single abnormal specimen.

Clause 9 lists the test report items: reference to the standard, product designation, date of manufacture and/or batch number if known, primer details, liquid-to-powder proportions, mixing method and total mixing time, thickness used, bond strength, mode of failure, any deviations, and the test date. This gives laboratories and buyers a consistent record for comparison and traceability.

What terms does oSIST prEN 13408:2026 define?

• Bond strength - force per unit area applied perpendicularly and centrally to the bonded area to cause failure.
• Floor levelling compound - the material used to build a homogeneous layer on the substrate before floor coverings are installed.
• Underlayment - the set layer produced with the levelling compound on the test slab.
• Standard test conditions - the controlled temperature, humidity, and air-circulation conditions used for conditioning and testing.
• Primer - a preparatory coating used only when specified by the manufacturer for the compound.
• Mode of failure - the way the specimen breaks, reported using EN ISO 10365 categories.
• MPa - the unit used for the calculated bond strength result.

Who uses oSIST prEN 13408:2026?

oSIST prEN 13408:2026 is used by manufacturers of cementitious and calciumsulfate-based floor levelling compounds when they need to verify bond performance. It is also used by test laboratories carrying out laboratory testing, by quality managers checking batch consistency, and by technical staff preparing product data or test reports.

The standard is relevant in the flooring and construction materials sector, especially where subfloors are prepared before installation of floor coverings. It helps users measure a property that affects whether a levelling compound will stay bonded to the substrate in service.

What changed in oSIST prEN 13408:2026 from the previous edition?

oSIST prEN 13408:2026 supersedes EN 13408:2002. The foreword states these changes compared with EN 13408:2002:

• the term “hydraulic setting floor smoothing and/or levelling compounds” was changed to “cementitious and calciumsulfate-based floor levelling compounds”
• the scope was made more specific
• the normative references were updated
• editorial changes were made

Which standards are used with oSIST prEN 13408:2026?

What does the oSIST prEN 13408:2026 document contain?

oSIST prEN 13408:2026 contains a defined pull-off test method rather than a product specification. It lays out the principle of bonding metal plates to a set levelling-compound specimen on a concrete slab and then measuring the force needed to pull them off.

The document also includes the test conditions, apparatus, specimen preparation, and the 14-day test timing. Its calculation and reporting clauses give a repeatable way to turn individual pull-off results into a mean bond-strength value and a traceable test report.