SIST EN 13879:2004

SIST EN 13879:2004 is the Slovenian adoption of EN 13879:2002 from CEN. It specifies a method for determining the strength, stiffness, creep and duration of load of wood-based panels when they are loaded in edgewise bending, so laboratories and panel producers can compare panel performance in a consistent way.

What does SIST EN 13879:2004 specify?

SIST EN 13879:2004 specifies the test method for wood-based panels in edgewise bending and states that it is not applicable to extruded panels. The standard is organized into scope, normative references, principle, test pieces, conditioning, procedure, expression of results, and test report.

The document is built around three test routes linked to other standards:

• EN 310 for small size test pieces
• EN 789 for medium size test pieces
• ENV 1156 for test pieces used for duration of load and creep

This structure matters in practice because the test piece size, conditioning, procedure and reporting all follow the chosen test route.

What are the key requirements of SIST EN 13879:2004?

SIST EN 13879:2004 measures edgewise bending properties by preparing panel strips into a test piece that is then tested according to one of three referenced bending methods. The standard ties the preparation and reporting steps to the chosen method, so the same panel can be assessed in different test formats without changing the basic principle.

Test piece preparation

Each test piece shall contain strips from only one panel and one panel direction. That means results stay traceable to a specific panel and a specific direction, which is important when comparing properties along and across the panel.

The strips are fixed face to back, and the adhesive or fastener at the loading points and supports shall have low modulus so it does not increase stiffness or strength. In practice, the connection must hold the strips together without affecting the measured bending result.

Choice of test size

The standard defines three test-piece sizes:

• small size test pieces for EN 310
• medium size test pieces for EN 789
• test pieces for duration of load and creep for ENV 1156

For each size, the number of strips per test piece and the number of test pieces per panel depend on panel thickness. This matters because the test program has to match the panel thickness and the selected reference method.

Special preparation for less homogeneous materials

For less homogeneous materials such as plywood, LVL, OSB and solid wood panels, panels thicker than 16 mm are tested with a height of 50 mm, and the test-piece size is adjusted according to the relevant test method. This prevents a single fixed geometry from being used where the material structure needs a different test setup.

Conditioning, procedure and reporting

Before testing, the test pieces shall be conditioned to constant mass according to the relevant test standard. The procedure, expression of results and test report are then carried out according to EN 310, EN 789 or ENV 1156, depending on the test route chosen. In practice, the standard does not stand alone for reporting - it points the user to the test standard that governs the final evaluation.

What terms does SIST EN 13879:2004 define?

Wood-based panels are the panel products covered by the standard and tested for bending performance in edgewise loading.

Edgewise bending is bending applied to the panel in the edgewise orientation, which is the loading condition the standard is designed to evaluate.

Strength is the load-carrying capacity measured in the edgewise bending test.

Stiffness is the resistance to deflection in edgewise bending, which helps users judge how much the panel will bend under load.

Creep is the time-dependent increase in deformation under sustained load.

Duration of load is the effect of how long the load is applied, which is important for long-term use conditions.

Test piece is the prepared assembly of panel strips that is placed in the bending test.

Who uses SIST EN 13879:2004?

SIST EN 13879:2004 is used by testing laboratories, wood-based panel manufacturers, and quality teams that need comparable bending data for panel products. It is also useful for buyers and specifiers who need test results that show how a panel behaves when loaded on edge, especially for strength, stiffness, creep and duration of load. In practice, it supports product development, routine quality control, and technical comparison between panel types and panel directions.

What changed in SIST EN 13879:2004 from the previous edition?

SIST EN 13879:2004 is identical to EN 13879:2002.

Which standards are used with SIST EN 13879:2004?

EN 310 provides the flatwise bending method used for the small size test pieces, and it also governs the expression of results for that route.

EN 789 provides the bending test method for timber structures and is used for the medium size test pieces and their result reporting.

ENV 1156 provides the method for determining duration of load and creep factors, and it is used for the dedicated creep and duration-of-load test pieces.

What does the SIST EN 13879:2004 document contain?

The document includes a principle section that explains how the test is assembled from panel strips, plus detailed test-piece preparation rules for three test routes. It also contains three tables that set the number of strips and test pieces by panel thickness, and three figures that show the test-piece geometries.

The remaining clauses cover conditioning, the procedure for each test size, and how to express results. The last clause points the user to the relevant test standard for the test report, so the final reporting format follows EN 310, EN 789 or ENV 1156.