Story | 09/19/2023 12:29:48 | 3 min Read time

How to ensure the strength of your plywood product

Plywood intended for use as a permanent building component must come with the manufacturer's CE mark Declaration of Performance (DoP) or UKCA mark Declaration of Conformity (DoC). The technical strength of WISA® plywood products of any type and thickness is stated in the declarations. DoPs and DoCs are also available for WISA plywood products for non-structural use.

WISA plywood for construction is CE-marked and appropriately classified. In the UK, the UKCA mark corresponds to the CE marking. The performance level of WISA plywood is precisely defined and documented. Manufacturing and quality control processes are always checked and approved by a certified third party. 

Designers and builders have several ways of ensuring that the chosen plywood product is strong enough and suitable for the intended use. 

  1. Precise strength properties can be found in the DoP reference list, easily available on UPM Plywood's website either through the DoP search tool or the reference list. 

  2. Using the DoP Reference List | WISA PLYWOOD or DoC Reference List, you can search for the panel that suits your project the best.
    • structural or non-structural use 
    • coated or uncoated 
    • birch or conifer plywood 
    • fire-retardant or water-repellent 

  3. The DoP number for WISA plywood can be found either on the plywood panel or packaging or in the delivery documents.

  4. Basic information about the panel is available in the website's Product Catalogue or the fact sheet, which is offered in several languages. This information can be used as a preliminary aid during the design phase.

WISA plywood for structural use is CE and UKCA marked 

Uncoated WISA plywood products generally have the CE marking printed on the panel. The DoP or DoC number for coated plywood is specified on the packaging and in the delivery documents. 

“CE-marked products are divided into structural and non-structural products. The 'S' stamp indicates a structural product whereby European importers and manufacturers provide the strength values in a comparable manner in the DoP. We also have DoP documents for ‘NS’-stamped non-structural WISA products,” emphasises Senior Researcher Simo Koponen from UPM Plywood. 

Structural plywood is needed when the panel remains a permanent part of the building, for example, as a stiffening or load-bearing structure. The required performance level is determined by the intended use and operating conditions, and the use classes are defined in the design standard for load-bearing wooden structures in Eurocode 5. 

  • Use Class 1: As a load-bearing structural component for indoor use, EN 636-1 
  • Use Class 2: As a load-bearing structural component for covered outdoor use, EN 636-2 
  • Use Class 3: As a load-bearing structural component for outdoor use when coated and edge-protected, EN 636-3 

When used in construction, the plywood panel may be required to meet a certain fire or emission classification, which requires a CE marking for that classification and the related DoP document. 

By varying the structure of the panel, i.e., by changing the orientation of the veneers, the bending strength can be reinforced in a certain direction; this also appears in the DoP. 

“UPM Plywood has a long tradition of testing and assuring the quality according to the standards, so you can trust the figures. If necessary, we advise on choosing the correct plywood product, panel structure and thickness. For more special applications, we can, if needed, test or simulate different applications,” assures Product Manager Harri Nieminen, who is responsible for WISA birch plywood products.

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